Intro to RADIOSS v14 Exercises HM 2017-03-17

Intro to RADIOSS for Impact Analysis Including Examples using HyperCrash and HyperMesh Desktop

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Table bl e of Contents on tents

Intro Intr o to RADIO ADIOSS for fo r Impact Ana An alysi ly sis s Examples Examples using HyperMe HyperMesh sh Desktop Desktop Chapt er 3: Runn in g RADIOSS Exer ci ses ........................ ................................. .................. .................. .................. .................. .................. .............. ..... 4

Exercise 3: First Run with RADIOSS......................................................................................... 5 Chapter 5: Material Characterization Exercises ....................................................................... 18

Exercise 5a: Tensile Test Setup .............................................................................................. 19 Exercise 5b: HyperElastic Bushing................... Bushing............................ .................. .................. ................... ................... .................. .................. ................ ....... 26 Exercise 5c: Ball Drop on Glass Plate ................... ............................ .................. .................. .................. .................. .................. .................. ............ ... 36 Chapt er 6: Int erf ace Mod elin g Exerc is es .................. ........................... .................. ................... ................... .................. .................. .................. ........... 51 51

Exercise 6a: TYPE7 Contact in a Crush Tube ...................... ............................... ................... ................... .................. .................. ............. .... 52 Exercise 6b: TYPE24 Contact in a bolted cantilever b eam ................... ............................ .................. .................. ................ ....... 70 Chapter 7: Kinematic Condition Exercises ............................................................................... 79

Exercise 7: Three Point Bending ............................................................................................. 80 Chapt er 9: Tim est ep Cont ro l Exerc is es ................... ............................ .................. .................. .................. .................. .................. .................. ........... 102

Exercise 9: Time Step Control on Bottle Top Load Simulation .......................... ................................... .................. ........... 103 Capst on e Exerc is es .................. ........................... ................... ................... .................. .................. .................. ................... ................... .................. .................. .............. ..... 116

Capstone: Cell Phone Drop ................................................................................................... 117 Capstone: Bumper Impact ..................................................................................................... 121 Ap pen di x A: Usi ng RADIOSS w it h Hy per Stu dy ....................... ................. .................. ............ 125

Exercise A1: Material Calibration Using System Identification ................... ............................ .................. ................. ........ 130 HS-4220: Size Optimization Study on an Impact Simulation Using RADIOSS .......... ................... ........... .. 141

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Intro to RADIOSS RADIOSS for Impact Analysis 3 Proprietary Information of Altair Engi neering, Inc.

Chapte hapt er 3: Runni un ning ng RADIO ADIOSS Ex er cis ci s es

4 Intro to RADIOS RADIOSS S for Impact Analysis Proprietary Information of Altair Engi neering, Inc.

HyperWorks HyperWorks 14.0 14.0

Exerc Exercis ise e 3: 3: First Fir st Run w ith RADIO RADIOSS SS Objectives    

Become familiar with the format of of RADIOSS RADIOSS Engine and Starter Starter files Know how to use HyperWorks Solver Run Manager to to execute a RADIOSS simulation Analyze starter and engine output files Learn to post-process post-process key results from an explicit analysis with HyperView.

Model Description

The model simulates an impact of a thin-walled, closed hat section on a rigid wall.

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Simulation time: 50 ms

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Uniform thickness = 1.5 mm

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Input files for this tutorial: FIRST_RUN_0000.rad and FIRST_RUN_0001.rad

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Units: Length (mm), Time (ms), Mass (g), (g), Force (N) (N) and Stress (MPa)

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Results requested:

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o

/ANIM/VECT/DISP

Displacements

o

/ANIM/VECT/VEL

Velocities

o

/ANIM/ELEM/EPSP

Plastic Strain

o

/ANIM/ELEM/VONM

VonMises Stress

o

/ANIM/ELEM/ENER

Energies

o

/ANIM/ELEM/HOURG

Hourglass Energy

Johnson-Cook Elasto-Plastic Material /MAT/LAW2. o

ρ = 7.8e-3 7.8e-3 g/mm3 [Rho_I]

Initial density

o

E = 210,000 MPa [E]

Young’s modulus

o

ν= 0.29

[nu]

Poisson’s ratio

o

y =

[a]

Yield stress

o

Κ= 450.0 MPa

[b]

Plasticity hardening parameter

o

n = 0.5

[nu]

Plasticity hardening exponent

o

MAX=

[SIG_max0]

Max Stress

180 MPa

350 MPa

Problem Probl em Setup Setup Copy the files: FIRST_RUN_0000.rad, files: FIRST_RUN_0000.rad, FIRST_RUN_0001.rad into a working directory.



Step 1: Scroll thr ough the RADIOS RADIOSS S Engi Engi ne and Starter Files, FIRST_RUN_0000.rad and FIRST_RUN_0001.rad in a text editor and ob serve Keyword Keyword c ards denoted with a “/” With a modulus of 210,000 MPa and a density of 0.0078, calculate the speed of sound in the material.

Speed of sound in steel rail = _________________________

The length of the rail is about 1,000 mm. Using the speed of sound and the rail length, calculate the time it takes for a shock wave to travel from one end of the rail to the other and enter this value as SIMULATION_ TIME in the Engine file: FIRST_RUN_0001.rad file. Time for sound to travel length of rail = ______________________________________ We would like to have 20 animation outputs outputs of our analysis. Using the total simulation time, calculate calculate the time frequency animation output output such that 20 animation steps steps are created. Enter this value as ANIMATION_OUTPUT_FREQUENCY.

/VERS/140 # Simulation Time /RUN/FIRST_RUN/1/

SIMULATION_ TIME # Animation Output Frequency /ANIM/DT #

TSTART

TFREQ

0.000000 ANIMATION_OUTPUT_FREQUENCY /PRINT/-10 /RFILE #

NCYCLE

IREAD

IWRITE

5000 0 0

Note that the time history file output request /TFILE is set to 0.1 ms for the restart later in this exercise. Also note that the engine keyword /DT/NO DA tells the solver to use nodal t ime step.

6 Intro to RADIOS RADIOSS S for Impact Analysis Proprietary Information of Altair Engi neering, Inc.


Step 2: Open the RADIOSS Run Manager fr om t he Windows Start Menu

Step 3: Select t he Starter f ile FIRST_RUN_0000.rad as the “Input file” and Run with – onestep option.

Tip:

Option –onestep tells RADIOSS to only run a single step of the simulation (in this case the starter) and stop. If not specified, then the engine will run automatically if the starter finds no fatal errors and if there is an engine file in the directory).

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Intro to RADIOSS for Impact Analysis 7 Proprietary Information of Altair Engi neering, Inc.

Step 4: Review the Starter output file FIRST_RUN_0000.out and verify the model: Use a text editor or select view -> Output File from the window as shown below to view the Starter output file: FIRST_RUN_0000.out and look for errors or warnings at end of the file. Note how the Starter output file echoes the input defined in the Starter input deck.

The time step calculated by the R ADIOSS Starter is reported in the Starter output file. Search the file for “time step” and review the value for Shell, Spring and Nodal time step. Which of these is controlling a stable solution?

Step 5: Select the Engine file FIRST_RUN_0001.rad as the “Input file” and Run.

Tip:

Option –nt 4 tells RADIOSS to run the analysis on 4 threads (using 4 CPU) this should speed up the analysis

Step 6: Review the Engine output file FIRST_RUN_0001.out with a text editor 8 Intro to RADIOSS for Impact Analysis Proprietary Information of Altair Engi neering, Inc.

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What time step is the solver using? Based on what entity?

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Check the % Energy Error ( ERROR) and Mass Addition ( MAS.ERR) at the end of the computation.

Step 7: Review the results file FIRST_RUN.h3d with HyperView 1. Click the Results button in the Solver View window

2. Or, open HyperView , load the file FIRST_RUN.h3d, and then Appl y.

3. Click the Entity Attributes button to bring up the Entity Attributes panel. Click on the Rigid Wall component in the graphics area and select the Transparent shading button to make the component transparent.

4.

Click the Contour button to enter the Contour panel. Select Velocity (v) for the Result type: and click Appl y.

This will contour the velocities at Time=0 to verify initial conditions.

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5. Change the contour to VonMises(s) stress.

6. Use the Next Time/Angle/Step button

on the animation toolbar to incrementally step

through the animation of the Stress Contour. This allows you to see the stress wave propagating from the front of the rail to the rear of the rail. Check the time it takes the stress wave to reach the back end of the rail. How does it compare to your calculation from Step 1?

10 Intro to RADIOSS for Impact Analysis Proprietary Information of Altair Engi neering, Inc.

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When this step is completed, close the HyperView session.

Step 8: Contin ue the simu lation by settin g a longer run tim e 1. Make a copy of the RADIOSS engine file FIRST_RUN_0001.rad and change the name to FIRST_RUN_0002.rad. 2. Update the engine file with a new end time of 50 msec by updating the line beneath the /RUN/FIRST_RUN/2/ command to 50.0 and updating the animation output to 2.5 msec beneath /ANIM/DT as shown below.

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/VERS/140 # Simulation Time /RUN/FIRST_RUN/ 2/

50.0 # Animation Output Frequency /ANIM/DT #

TSTART

TFREQ

0.000000 2.5 /PRINT/-10 /RFILE #

NCYCLE

IREAD

IWRITE

5000 0 0 Select the second Engine file (FIRST_RUN_0002.rad) as the “Input file” and Run

Notice that the animation files continue numbering from where the first run left off. Also notice that a second time history file (T02) is created.


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Step 9: Prepare a four-window layout for reviewing th e results 1. Open a new HyperView session.

.

2. Split your page into 4 windows using the Page Window Layout :

3. In the first window, use the HyperView client to load the FIRST_RUN.h3d file with a transparent rigid wall and contoured with Von Mises stress as in Step 7.

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4. In the 3 new windows, load the HyperGraph 2D client using the client selector if they are not automatically loaded.

5. Click on the top right window to make it current. Step 10: Plot the Rigid Wall Force as a function of time

1. From the Build Plots panel , load the Time History File FIRST_RUN_T01 - note that the second file FIRST_RUN_T02 will also be loaded. 2. Select the Y-type, Y-Request, and Y-Component as Rigid wall > RIGID WALL 1 > Resultant and click Apply.


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Step 11: Plot energy curves in the lower left-hand window

1. Click on the left bottom window to make it current. 2. From the Build Plots panel, select the Y-Type: Global Variables, multiple Y Request: Internal Energy, Kinetic Energy, Hourglass Energy, a nd TTE-Total Translational Energy by control-clicking on each selection, and select the Y Component: MAG. Click Appl y to create the plot.

Step 12: Plot Global Variables > Time Step vs Time in the remaining window


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Step 13: Save the session to a file Once the post-processing is done, it can be saved by writing a session file or a report template: 1) A session file (*.mvw) exactly reloads your post-processing on the same results files, or results files of the same names (e.g. after a re-run) 2) A report template (*.tpl) allows post-processing of new simulation results (new run, different filenames) based on the template format. For this exercise we will create both a session file ( *.mvw) and a template file (*.tpl) which will be used in later exercises.

1. Click on File > Save > Session and save the file as Rail_Results.mvw. 2. Click on File > Save as > Report Template and save the file as Rail_Results.tpl.

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Chapter 5: Material Characterization Exercises


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Exercise 5a: Tensile Test Setup Objectives 

Become familiar with Johnson-Cook Material Law 2



Understand how to define boundary conditions /BCS and imposed velocity /IMPVEL



Define key Engine file cards

Model Description

The uniaxial tensile test uses a quarter size mesh with symmetric boundary conditions to reduce the solver run time.

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UNITS: Length (mm), Time (ms), Mass (kg), Force (kN) and Stress (GPa) Simulation time: 10.0 ms Boundary Conditions: o The 3 upper right nodes (TX, and RY, RZ) o The center node on right is totally fixed (TX, TY, TZ, RX, RY, RZ) o A symmetry boundary condition on all bottom nodes (TY, RX, RZ) At the left side a constant velocity is applied = 1 mm/ms on -X direction. Tensile test specimen dimensions = 11 x 100 with a uniform thickness = 1.7 [mm] Note the slight perturbation of the top right node so that necking will form at the center of the specimen

Johnson-Cook Elastic Plastic Material /MAT/PLAS_JOHNS (Aluminum 6063 T7) = 2.7e-6 Kg/mm3 [Rho_I] Initial density E = 60.4 GPa [E] Young’s modulus = 0.33 [nu] Poisson’s ratio a = 0.09026 GPa [a] Yield Stress b = 0.22313 GPa [b] Hardening Parameter n = 0.374618 [n] Hardening Exponent [SIG_max] Maximum Stress max = 0.175 GPa [EPS_max] Failure Plastic Strain max = 0.75

Problem Setup Copy the files: tensile_0000.rad to a working directory

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Step 1: Start HyperMesh Desktop u sin g the RADIOSS Blo ck140 User Prof ile and import the solver deck tensile_0000.rad Step 2: Create and assign the materi al Aluminum to the test specimen 1. Right-click in the Model Browser and select Create > Material . 2. Use the Entity Editor to input the values as shown:

3. In the Model Browser, select the component PSHELL1 and click on the Mat_ID and select Aluminum to set the material.


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Step 3: Create and assign t he shell pr operty sheet_1.7 to the test specimen 1. Right-click in the Model Browser and select Create > Property . 2. In the Entity Editor, set the Name: to sheet_1.7 and enter Thick: of 1.7.

3. In the Model Browser, select the PSHELL1 component and click on the Prop_ID in the Entity Editor and select sheet_1.7 to set the property.

Step 4: Create boundary condit ions for s ymmetry and general const raint 1. From the pull-down menu, select Tools > BCs Manager . 2. For Name, enter constraint1, set Select type to Boundary Condition and set GRNOD to Nodes.

3. Click on the nodes entity selector. Select the three nodes shown in the figure below and click proceed .

4. Fix degrees of freedom Tx , Ry and Rz.

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5. Click create at the bottom of the tab to create the constraint. 6. Create a new boundary condition with the Name of constraint2 with the following node selected and all six degrees of freedom constrained.

7. Create a third boundary condition with Name constraint3 with the following nodes constrained in DOFs Ty , Rx , and Rz.

Step 5: Create Imposed Velocity 1. Using the BC’s Manager, create a new boundary condition with Name velocity, Select type set to Imposed Velocity and set GRNOD to Nodes. Select the nodes shown in the image below.


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2. Set the Direction to X with Scale X set to 1 and Scale Y set to -1.0. 3. Click the Create/Select curve button to set the Curve ID. A curve editor appears.

4. Create a new curve with the Name Load with values as shown in table below.

5. Close the Curve editor to assign the created curve to this constraint. 6. Click create to create the velocity boundary condition. Tip: Note that the graphics may not take the Y scale factor into account.

Step 6: Create the engin e file. 1. From the pull-down menu, select Tools > Engine file assistant. Assign the following:

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This tool creates the following basic Engine file:

Step 7: Export the model as TENSILE_0000.rad Step 8: Run TENSILE_0000.rad in RADIOSS Step 9: Review the list ing fil es for this run and verify the results 7. See if there are any warnings or errors in the .out files. If so, list them below. 8. Using HyperView, plot the displacement and strain contour and compare to the results on the following page.


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EXERCISE EXPECTED RESULTS

Displacement Contour (mm) @ Time=8.0s

Plastic Strain Contour at Time=8.0s

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Exercise 5b: HyperElastic Bushing Objectives 

Become familiar with RADIOSS Hyperelastic material law



Understanding how to set up sequential loading conditions.

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This exercise demonstrates how to simulate a rubber bushing given t he following load sequence:

o o o

Translation, Transverse (10 mm) Translation, Longitudinal (5 mm) Torsion (20 Degrees)

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UNITS: Length (mm), Time (ms), Mass (kg), Force (kN) and Stress (GPa)

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Simulation time: 1.5 ms in three steps of 0.05 ms for each load case

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The outer circumference area is fixed on all translational DOFs (TX, TY, TZ) and the c enter node is fixed in the X translation and the X and Y rotation (TX, RX, RY)

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The bushing dimensions are: thickness = 100 mm, External Diameter = 200 mm and internal diameter = 50 mm.

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Hyper-Elastic Material /MAT/LAW42 (Rubber) 

= 6.0 e-6 ѵ = 0.495

[kg/mm3] [-]

Initial density Poisson’s ratio

= 0.600 1 = 2 2 = -2

[GPa] [-] [-]

Ground Shear mod. 1 Alpha 1 Alpha 2

1

Problem Setup Copy the files: GASKET_0000.rad to a working directory 26 Intro to RADIOSS for Impact Analysis Proprietary Information of Altair Engi neering, Inc.

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Step 1: Load HM Deskt op Block140 profile & import GASKET_0000.rad Step 2: Create a new M42_OGDEN material nam ed Rubber and assign as th e Mat_Id for the GASKET component

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Step 3: Create a new P14_SOLID pro perty named Bushing and assign as th e Prop_Id for the GASKET component


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Step 4: Create a rigid bo dy at the center of the gasket 1. Create a new component named RigidBody2.

Tip: When created, the component name should appear in bold, indicating it is the current component and all new elements created will be assigned by default to this part.

2. In the 1D > rigids panel, switch the selector nodes 2-n to multiple nodes, and switch the

primary node to calculate node. 3. Click on the nodes entity selector and pick any node on t he inner face of the gasket. 4. Click on the nodes entity selector to bring up the advanced selector menu and select by face.

HyperMesh Desktop will find and select all nodes on that inner face. 5. Click create to create the rigid body and click return to exit the panel.

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Step 5: Define a inner fixed boun dary conditi on on th e bushing new boun dary condition on the outer circ umference of bushing 9. From the Tools drop-down menu, start the BC’s Manager . 10. For Name, enter OInneruter_BC, set Select type to Boundary condition and set the

GRNOD to Nodes. 11. Select the master node of rigid body created in the previous step. Click Proceed . 12. Check the Tx translational and Rx, Ry rotational degrees of freedom. 13. Click Create at the bottom of panel to create the inner fixed boundary condition.


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Step 6: Define the imposed displacements on the master node of the rigi d body 14. In the BC’s Manager , create a new boundary condition named DISP_Y of type Imposed

displacement and set the GRNOD to Nodes, selecting the master node of rigid body. 15. Set the Direction to Y, and Scale X and Scale Y to 1.0. 16. Create a new curve under Curve ID using the XY curve editor named DISP_Y containing the points {0, 0}, {0.5, 10}, and {1.0, 10}. Click update and close the XY curve editor GUI. 17. Click create to create the boundary condition.

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18. Create a new Imposed Displacement boundary condition named DISP_Z on the master node of rigid body with the Direction to Z, and Scale X and Scale Y to 1.0 which uses a new curve named DISP_Z containing the points {0, 0}, {0.5, 0}, {1.0, 5}, and {1.5, 5}. 19. Create a third Imposed Displacement boundary condition named ROT20DEG_Z on the master node of rigid body with the Direction to ZZ, and Scale X and Scale Y to 1.0 which uses a new curve named ROT20DEG_Z containing the points {0, 0}, {1, 0}, {1.5, 0.349}, and

{2, 0.349}.

Step 7: Define a new boundary condit ion on t he outer circumf erence of bushi ng 20. From the Tools drop-down menu, start the BC’s Manager . 21. For Name, enter Outer_BC, set Select type to Boundary condition and set the GRNOD to Nodes. 22. Click on the nodes entity selector and pick any node on the outer face of the gasket.


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23. Click on the nodes entity selector to bring up the advanced selector menu and select by face.

HyperMesh Desktop will find and select all nodes on that outer face. Click Proceed . 24. Check the Tx, Ty, and Tz to fix the translational rotational degrees of freedom. 25. Click Create at the bottom of panel to create the outer fixed boundary condition.

Step 78: Set the control c ards to a final run t ime of 1.51 ms with t ime frequency of 0.05 ms, a print t o the *.out fil e and screen every 100 cycles, time hist ory inf orm ation w rit ten in 0.0015 inc rements, and vo n Mises (VONM), density (DENS), and pressure (P) outputs to th e A* and h3d fi les Tip: Use the HyperMesh Solver Browser from View > Browsers > HyperMesh > Solver to set up the following control cards and parameters: Keyword Type

Keyword

Parameter

Parameter Value

ENGINE KEYWORDS

TITLE_ENGINE

Status

[Checked]

CONTROL CARDS

TITLE

TITLE

GASKET

ENGINE KEYWORDS

RUN

RunName

GASKET

ENGINE KEYWORDS

RUN

Tstop

1.5

ENGINE KEYWORDS

PRINT

Status

[Checked]

ENGINE KEYWORDS

PRINT

N_print

-100

ENGINE KEYWORDS

ANIM/ELEM

Status

[Checked]

ENGINE KEYWORDS

ANIM/ELEM

VONM

[Checked]

ENGINE KEYWORDS

ANIM/ELEM

DENS

[Checked]

ENGINE KEYWORDS

ANIM/ELEM

PRES

[Checked]

ENGINE KEYWORDS

ANIM/DT

Status

[Checked]

ENGINE KEYWORDS

ANIM/DT

TStart

0

ENGINE KEYWORDS

ANIM/DT

Tfreq

0.05

ENGINE KEYWORDS

/TFILE

Time_frequency

1.5e-3

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Step 98: Export the model to GASKET_0000.rad Step 109: Run the model i n RADIOSS Step 110: Review the list ing fil es for thi s run and verif y the results 26. See if there are any warnings or errors in .out files.

27. Using HyperView plot the displacement and strain contour and vectors.


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Displacement Contour for the load condition (mm)

Von Mises Stress Contour at the end of the simulation

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Exercise 5c: Ball Drop on Glass Plate In the course of this exercise, users will become familiar with /PROP/SH_SANDW properties, learn how to create brittle material models with failure criteria based on forming limit diagram (FLD) information, and compare results from baseline models to that of a model incorporating XFEM setup. This exercise demonstrates how to set up a ball i mpact on regular glass versus safety glass that has a thin layer of plastic. In all cases an FLD failure model i s defined for shell rupture. These models are then updated to include XFEM (eXtended Finite Element Method) in which failure can propagate across elements (rather than along mesh lines). Note: XFEM requires version 14.0.220 or later.

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UNITS: Length (mm), Time (s), Mass (Mg), Force (N) and Stress (MPa) Simulation time: *_0001.rad [0 – 0.025 s] Boundary Conditions: o All degrees of freedom will be constrained on the master node of a rigid body connected to top and bottom of rubber frame o An initial velocity is given to a spherical rigid wall Johnson-Cook Elastic Plastic with Brittle Failure Material /MAT/PLAS_BRIT (Glass) ρ = 2.5e -9 Mg/mm3 E = 70,000 MPa ν = 0.2 a = 80.0 MPa b = 500.0 MPa n = 0.8

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[Rho_I] [E] [nu] [a] [b] [n]

Initial density Young’s modulus Poisson’s ratio Yield Stress Hardening Parameter Hardening Exponent

Johnson-Cook Elastic Plastic with Brittle Failure Material /MAT/PLAS_BRIT (Plastic)


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[Rho_I] ρ = 2.5e -9 Mg/mm3 E = 100.0 MPa [E] [nu] ν = 0.3 a = 10.0 MPa [a] b = 20.0 MPa [b] n = 0.5 [n] Eps_t1 = 0.6 [εt1] principal strain direction 1

Initial density Young’s modulus Poisson’s ratio Yield Stress Hardening Parameter Hardening Exponent Strain at the beginning of tensile failure in

Eps_t2 = 0.6 [εt2] principal strain direction 2

Strain at the beginning of tensile failure in

Eps_m1 = 0.7 [εm1] Eps_m2 = 0.7 [εm2] Eps_f2 = 0.8 [εf2] principal strain direction 1

Max tensile strain in principal strain direction 1 Max tensile strain in principal strain direction 2 Max tensile strain for element deletion in

Eps_f1 = 0.8 [εf1] principal strain direction 2

Max tensile strain for element deletion in

Problem Setup You should copy the files: BallDrop-Start_0000.rad

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Step 1: Import BallDrop-Start_0000.rad into HyperMesh Desktop RADIOSS Block140 profile Step 2: Define a new M27_PLAS_BRIT material named Glass with the following properti es and apply this material as the Mat_Id for t he Glass plate component:


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Step 3: Define a P11_SH_SANDW property named Glass_sandw with the foll owing properties and apply this pro perty as the Prop_Id for the Glass plate component:

Tip: For the N: Data layer information within the Table Data

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, enter the following:



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Step 4: Define the FAIL_FLD type failure property for the glass usi ng the FLD curve Glass failure model inclu ded in the model

Step 5: Create a rigid body at center of rubber fr ame Create a new component named RigidBody with no card image. In the rigids panel on the 1D page, switch nodes 2-n to multiple nodes and switch primary node to calculate node. Click on the nodes entity selector and select one node apiece on the outer faces of both Fixed upper and Fixed lower, respectively. Click again on the nodes entity selector to bring up the advanced selector and choose by face. Tip: HyperMesh Desktop will pick all of the nodes on the upper and lower faces. Click create to create the rigid body and click return to exit the panel.

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Step 6: Create a new load collect or named Constraint and constrain the central node of the rig id body i n all 6 DOFs Step 7: Create a spherical Rigid Wall with an Initi al Velocity In the nodes panel on the Geom page, create a new node with the XYZ coordinates {250, 250, 50.1}.

In the Model B rowser window, right-click and select Create > Rigid Wall . Complete the new Rigid Wall definition with the following parameters, selecting the newly created node as the Base node for the sphere and selecting the Glass plate component for gr_nod1 (S):


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Step 8: Set the cont rol c ards to a final run t ime of 0.025 s wit h tim e frequency for data outp ut of 0.0001 s, tim e frequency o f 0.001, plastic strain (EPSP) and von Mises (VONM) element r esult s, shell tensor stress (STRESS) and str ain (STRAIN) for all layers, and velocity (VEL) and d isplacement (DISP) vector output s and setting t he engine file to export separate from t he starter file. Keyword Type

Keywo rd

Parameter

Parameter Value

ENGINE KEYWORDS

TITLE_ENGINE

Title

Ball Drop

ENGINE KEYWORDS

RUN

RunName

Ball Drop

ENGINE KEYWORDS

RUN

Tstop

0.025

ENGINE KEYWORDS

TFILE

Time_frequency

1.0E-04

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ENGINE KEYWORDS

ANIM/ELEM

EPSP

[Checked]

ENGINE KEYWORDS

ANIM/ELEM

VONM

[Checked]

ENGINE KEYWORDS

ANIM/SHELL/TENS/STRAIN

ALL

[Checked]

ENGINE KEYWORDS

ANIM/SHELL/TENS/STRESS

ALL

[Checked]

ENGINE KEYWORDS

ANIM/VECT

VEL

[Checked]

ENGINE KEYWORDS

ANIM/VECT

DISP

[Checked]

ENGINE KEYWORDS

ANIM/DT

TStart

0

ENGINE KEYWORDS

ANIM/DT

Tfreq

1.0e-03

Step 9: Export the model as BallDrop-Finish_0000.rad and r un in RADIOSS

Step 10: Check the *.out files for warnings or errors and then review the results in HyperView, plotting the displacement contour


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EXPECTED RESULTS Glass only Model

Displacement Results

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Step 11: Update the model to include a middle layer of plastic Continue with the model in HyperMesh Desktop from the previous steps, adding a new material, Plastic Film, as shown below:

Edit the laminate property to replace the middle glass layer with the plastic film material just created.


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Step 12: Save the model as BallDrop-PlasticLayer_0000.rad and run in RADIOSS Step 13: Check the *.out files for warnings or errors and then review the results in HyperView comparing the plot of the displacement contour with that of the previous run

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EXPECTED RESULTS Glass and Plastic (Displacement Legend MAX 50)

Displacement Results


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Step 14: Import the previous models into new HyperCrash sessions and update the failure model to change the XFEM flag to 1 and reexport as BallDrop-Final_withXFEM_0000.rad and BallDropPlasticLayer_withXFEM_0000.rad respectively

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EXPECTED RESULTS Glass with XFEM (shattered layers displayed)

Glass and Plastic with XFEM (shattered layers displayed)


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Chapter 6: Interface Modeling Exercises

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Exercise 6a: TYPE7 Contact in a Crush Tube This exercise demonstrates how to set up a crush tube impact consisting of two C-channels seam welded together. The tube is 2mm thick in the first half of the tube and 3mm in the second half. One end has extra mass applied using a rigid body body. An initial velocity is applied to the tube and it impacts a rigid wall. Users completing this exercise will become familiar with the use cases of a Type 7 interface and Type 7 interface parameters Igap, Gapmin, and Inacti.

Rigid body t=3 mm t=2 mm

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Simulation time: 30.0 ms



Boundary Conditions:

o

All degrees of freedom except in the Z-direction will be constrained on the master node of a rigid body connected to the end of the tube

o

An initial velocity is given to all nodes in the model

Johnson-Cook Elastic Plastic /MAT/PLAS_JOHNS (Steel) parameters ρ = 7.85e-6 kg/mm3

[Rho_I]

Initial density

E = 210 GPa

[E]

Young’s modulus

ν = 0.3

[nu]

Poisson’s ratio

a = 0.206 GPa

[a]

Yield Stress

b = 0.45 GPa

[b]

Hardening Parameter


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n = 0.5

[n]

Hardening Exponent

Steel Section Properties ● Element Formulation = QEPH (Ishell = 24) ● Gauge = 2mm and 3mm

Problem Setup Copy the file: TubeCrush-Start_0000.rad to a working directory.

Step 1: Impor t TubeCrush-Start_0000.rad int o HyperMesh Desktop Step 2: Review the material properties of the Steel to verify that the parameters match those given in the exercise introduction Step 3: Review the shell p roperty fo r th e steel parts Step 4: Edit the rigid body d efinitio n to inc lude a mass of 500 1. Select Tools > RBODY Manager to access the RBODY Manager tab. 2. Right-click on the RBODY entry in the tab and select Edit Card… to open the card image editor for the element. 3. Scroll down in the top part of the editor to find the MASS entry and change the value to 500. 4. Click return to close the Card Image dialog. Close the RBODY Manager tab.

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Step 5: Usin g the BC Manager, cr eate a BC named Constraint on the rigid body master node in all degrees of freedom except Tz

Step 6: Create a tied interface between the flanges of the C-sections making up the tube. Recall that by default a Type 2 interface is a kinematic con ditio n. 1. In the Model Browser window right click Create > Contact in the drop down menu to open the Create Grou p dialog box. Change the Card Image TYPE2 and name the contact Seamweld . 2. To set the slave nodes, click on the Grnod_id (S) Nodes entity selector. When the Add entities panel appears, change the panel’s entity selector to nodes


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Select the nodes on the ends of the C-channels as shown and click add in the panel to add them to the int erface:

3. Click return to exit the panel and return to the dialog box entries. 4. Select the Surf_id (M) Elements , entity selector and in the select entities dialog change the entity selector to Elements. Select the inner area of the C-Channel elements as shown in the next figure..

5. Set the dsearch to 5. HyperWorks 14.0


Tip: The dsearch distance will limit the search so only the relevant master surfaces will be found for the slave nodes.

Step 7: Define a self contact Type 7 interface for the C-channels wit h th e following parameters shown below: The default contact gap thickness method defined by Igap in TYPE7 contact is called constant gap. This means that the actual thickness of the parts is not used for contact but instead the thickness of the parts is considered the same for all parts and is defined by GapMin. If GapMin is not defined then the constant gap thickness is calculated by RADIOSS. In this first example, constant gap thickness is used and the results will be compared to another iteration that uses variable gap where the actual part thickness is used for contact.

1. In the Model Browser window right click Create > Contact in the drop down menu to open the Create Grou p dialog box. Change the Card Image TYPE7 and name the contact

self contact. 2. Click on the Grnod_id (S) Nodes entity selector and change the entity type to Components and click on Components and pick all the Components in the model. 3. Click on the GSurf_id (M) Element entity selector and change the entity type to Components and click on Components and pick all the Components in the model. 4. Enter the best practices values of Istf = 4: K= min(Km,Ks) and Stmin= 1 kN/mm 5. Enter GapMin = 1.0 mm. Note: The value of Gapmin was chosen to be less than ½ thickness of the thinnest p art which should be small enough to avoid any initial penetrations but large enough to allow the contact forces to prevent penetration. 6. Enter a steel against steel friction value as Fric = 0.2. 7. Enter additional best practice value of Iform = 2.


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-

Step 8: Create infi nite plane rigi d wall named Wall at front of tube 1. In the Nodes panel, select the XYZ opti on , place the model in the XZ view , and click one of the nodes on the bottom of the c-channel three times to load its X, Y, and Z coordinates, respectively, into the display fields. Tip: The panel shows the Z-coordinate of the node is -304.5mm. This gives the user enough information to determine the proper offset for the base node of the infinite wall.

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2. Change the Z-coordinate of the node to -305 and click create to create a base node for

the wall offset from the front of th e C-channels by 0.5 mm. 3. Right-click in the Model Br owser and select Create > Rigid Wall

Rename the rigid wall to Wall and set the geometry type to Infinite Plane with the newly created node selected as the Base node, and a Normal vector of {0, 0, 1}, SLIDE set to 2 to enable friction, a fric parameter of 0.2, and a d value of 100 mm. Tip: d represents the distance to search for slave nodes, which is the distance inside of which nodes are ‘seen’ by the rigid wall as potential contacts.


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Step 9: Set the Initial Velocity for every node in the model to -13.3 Vz 1. Select Tools -> BCs Manager and enter the Name IniVel, and select type = Initial Velocity. 2. Switch GRNOD to Nodes and select all nodes in the model. 3. Define Vz as -13.3 mm/ms 4. Click create tab to create the initial velocity.

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5. Close the Utility panel.

Step 10: Define time histor y output b lock f or the rigi d wall force 1. Right click in the model browser and select Create > Output Block. 2. The Output Block with name outputblock1 of solver keyword /TH/NODE is created and appears in the Entity Editor (EE) in the bottom pane of the model browser. 3. Change Entity IDs to Groups. Change Keyword to RWALL. Then select Groups and select Wall. 4. Select NUM_VARIABLES and select 1. This will bring up a table in which the Var DEF should be entered. (DEF is for default outputs, which for a rigid wall are the forces: FNX, FNY, FNZ, FTX, FTY, FTZ). See EE image below:


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Step 11: Review the engine file settings. 1. Expand the Card folder in the model browser. Review the engine cards ENG_XXXX. Note that the ENG_TFILE card defines the frequency (Time_frequency) at which the time history file will output the Rigid Wall forces defined in the output block in Step 11.

Step 12: Expo rt and run in RADIOSS 1. Select File > Expor t > Solver Deck and click

enter TubeCrush-Iter1_0000.rad

2. Check the Merger starter and engine file to try exporting the starter and engine files in one file.

3. Click Export

Step 13: Review the outpu t fil es for warning s and errors and view the animation results in HyperView 1. While the model is running use a text editor to edit the TubeCrushIter1_0000.out file and search for WARINING

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2. Notice that there are two warning message #312 and #446 which are caused by nodes being a slave to in both the tied contact and rigid wall. Rigid walls and the default tied contact are both kinematic conditions and the same node cannot be a slave to two kinematic conditions. Thus RADIOSS calls them INCOMPATIBLE KINEMATIC CONDITIONS. In this situation RADIOSS automatically removes the tied contact slave nodes from the rigid wall 3. Using HyperView, plot the displacements and plot results with a Y-section cut at Y = 38.75.

EXPECTED RESULTS TubeCrush -Iter1 (Cons tant Gap = 1.0), sectio ned at Y = 40

Note: There are nodes that have penetrated the rigid wall. T his is due to incompatible kinematic conditions of the Type 2 interface and the rigid walls. The starter output file indicates that some nodes in the Type 2 interface have been removed from the rigid wall slave set.

Step 14: Update the contact gap opti on to use variable gap ( Igap = 2) in the Type 7 interface and rerun the model as TubeCrush-Iter2_0000.rad 1. Instead of using a constant contact gap thickness, it is more accurate to use the actual thickness of the parts in contacts which is called Variable Gap in RADIOS. 2. Edit the self contact and enter the best practices values of Igap = 2: Variable gap + scale correction Tip: For the most physical response, the contact gap f or shells should use the shell thickness. 62 Intro to RADIOSS for Impact Analysis Proprietary Information of Altair Engi neering, Inc.

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3. Export the model as TubeCrush-Iter2_0000.rad and run in RADIOSS.

4. While the model is running use a text editor to edit the TubeCrushIter2_0000.out file and search for WARINING. 5. Two more warnings message #343 and #477 are in the output file. The following warning is most concerning and is the cause for the strange behavior of the results. WARNING ID : 343 ** WARNING : INITIAL PENETRATIONS IN INTERFACE DESCRIPTION : -- INTERFACE ID : 2 -- INTERFACE TYPE : self contact THERE ARE 860 INITIAL PENETRATIONS ( CONCERNING 550 NODES )

Step 15: Replot the results and compare to the TubeCrush-Iter1 and TubeCrushIter2 runs i n HyperView

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EXPECTED RESULTS TubeCrush-Iter2 (Variable Gap = 2)

*NOTE: This model “blows up” due to the initial penetration in the self contact of the 3 mm shells at the top of the tube near the rigid body. The initial space between the flanges at the top of the tube is 2.1mm but since the shells are 3 mm thick; the solver sees 0.9 mm of penetration and applies a contact force as shown in the figure on the left to remove that penetration. The forces from the initial penetration then cause the unphysical mesh deformation at Time=1.0 on the right hand side. If there are no initial penetrations in a model, the contact force will be zero at time=0.0.

Step 16: Review the initial penetrations in HyperMesh 1. From drop down Mesh menu > Check > Components > Penetratio n 2. Using the Comps entity selector pick all the parts in the model and click check


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3. As shown in the next figure, expand the Penetrations section and pick PSHELL1 (1), and then penetration vector (2). There are tools in HyperMesh that can be used to remove the initial penetrations by moving the nodes of the mesh. However for this model the contact interface option, Inacti, will be used to automatically reduce the contact thickness gap.

2 1

Step 17: Use option to automatically reduce the contact gap thic kness in th e ini tial penetratio n area and r erun RADIOSS. 1. Edit the self contact and enter the best practices values of Inacti = 6: Gap is variable with time which will in areas of initial penetration cause the contact gap to be reduced by the penetration value plus 5%. 2. Export the model as TubeCrush-Iter3_0000.rad and run in RADIOSS. 3. While the model is running use a text editor to edit the TubeCrushIter2_0000.out file and search for WARINING. *NOTE: Edit the TubeCrush-Iter3_0000.out file in a text editor and notice the WARNING message about the initial penetrations still exists but now there is an additional message concerning the automatic reduction of the initial gap. REDUCE INITIAL GAP REDUCE INITIAL GAP WARNING ID : 343 ** WARNING : INITIAL PENETRATIONS IN INTERFACE DESCRIPTION : -- INTERFACE ID : 2 -- INTERFACE TYPE : self contact THERE ARE 860 INITIAL PENETRATIONS ( CONCERNING 550 NODES )

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EXPECTED RESULTS TubeCrush-Iter3 (Variable Gap setup)

Plot the contact forces to make sure they are zero at time = 0.0


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Step 18: Review the new mo del against the oth er variations in HyperView NOTE: Iteration 3 is closer to the correct physical stack-up crush h eight compared to iteration 1 because using variable gap uses the actual part thickness for contact.

NOTE: A comparison of the rigid body master node Z-Displacement between iteration 1 constant gap and iteration 3 variable gap is shown below. The displacement of iteration 3 is less because it does not crush as much.

NOTE: Plotting the rigid wall forces for the iteration 1 and iteration 3 below also shows the effect of the gap thickness. Iteration 3 shows an earlier rebound as a result.

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Step 19: Underst anding WARNING ID : 477, WARNING IN INTERFACE GAP WARNING ID : 477 ** WARNING IN INTERFACE GAP DESCRIPTION : -- INTERFACE ID : 2 -- INTERFACE TITLE : self contact MAXIMUM VARIABLE GAP=3.000000000000 HOWEVER GAP IS RECOMMENDED TO BE LESS THAN 1.339216052991

This message is similar to the FAQ in the RADIOSS help which deals with a self contact with constant gap. RADIOSS > Frequently Asked Questions:Contact Interfaces: What is the meaning of: WARNING ID 94? WARNING ID: 477 occurs when the maximum variable contact g ap thickness > twice the smallest side length of shell elements on the master side. When this happens there is a possible over stiffening of the structure if the element is compressed by 50% as shown in the following picture.


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In this model, the length of elements in the crushing or compression direction is ~ 7mm which is greater than the maximum variable gap so it should be fine to ignore this message. In a model with elements with edge length that approaches the thickness, Igap=3 can be used to reduce the contact thickness gap based on the element length which will remove this over stiffening behavior.

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Exercise 6b: TYPE24 Contact in a bolted cantil ever beam This exercise demonstrates how to use TYPE24 contact to simulate solid to solid contact of a bolted assembly. In this model, there is an initial intersection between the bolt and the parts bolted together. Three different values of the TYPE24 interface parameter, Inacti, are tested to see how TYPE24 handles the initial intersection.






Simulation time: 25.0 ms




o

All translation degrees of freedom are constrained on the edge nodes of the block

o

A total force of 0.72 kN is apply in the negative X direction on the end of the cantivlever beam

Johnson-Cook Elastic Plastic /MAT/PLAS_JOHNS (Steel plate) parameters ρ = 7.83e-6 kg/mm3

[Rho_I]

Initial density

E = 210 GPa

[E]

Young’s modulus

ν = 0.3

[nu]

Poisson’s ratio

a = 0.27 GPa

[a]

Yield Stress

b = 0.45 GPa

[b]

Hardening Parameter

n = 0.6

[n]

Hardening Exponent


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Johnson-Cook Elastic Plastic /MAT/PLAS_JOHNS (Steel bolt) parameters ρ = 7.83e-6 kg/mm3 [Rho_I] Initial density E = 210 GPa [E] ν = 0.30

[nu]

Young’s modulus Poisson’s ratio

a = 0.792 GPa [a]

Yield Stress

b = 0.51 GPa [b]

Hardening Parameter

n = 0.26

Hardening Exponent

[n]

Steel Section Properties ●

Element Formulation = HEPH (I solid = 24)

Problem Setup Copy the file: bolted_cantilever-Start_0000.rad to a working directory.

Step 1: Impor t bolted_cantilever-Start_0000.rad int o HyperMesh Step 2: Review the material properties of the Steel plate and Steel bolt to verify that the parameters match thos e given in the exercise introduc tion Step 3: Review the solid property fo r the steel parts Step 4: Review the already defined cr oss s ection wh ich i s us ed to calculate the cross sectional force in the bolt. 1. Select the Model tab, under Components turn off the plate and block parts. 2. Under Cross Section right click on bolt_section and select Review.

Note: The RADIOSS section is defined with a group of element and group of nodes.

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Step 5: Review the loading Force 1. In the Model tab, under Load Collectors right click on bolt_section and select Review to see the nodes that the concentrate force are applied to.

2. In the Entity Editor right click on Ifunct and select Plot Curve. Notice that the force is not applied until 5ms. This was done to see if there is any contact force applied in the first 5 ms due to initial penetration.

Step 6: Define a Type 24 interface named contact which inc ludes all the parts in the model. In the first simulation, the default Inacti option will be used. 1. In the Entity Editor right click and select Create > Cont act and enter self contact for the name. 2. Select Card Image = TYPE24 and select Yes to the pop-up message about changing the card image. 3. Define the best practices value of Isft=4, which uses the minimum stiffness between the slave and master entities. Enter Fric= 0.2, and Inacti = 1000, which means only small initial penetrations will be taken into account and larger penetrations ignored. 4. To create a TYPE24 self-contact interface only Surface 1 needs defined. In the Surf _ID1 (S) right click and change the entity type to Set. 5. To the left of the entity selector right click and pick Create to create a new set.

6. Beside name enter self contact surface 7. Select Card Image = SURF_EXT which creates surfaces from the external faces of the solid elements. 8. Click on Components and select all three parts in the model and click Close

Step 7: Export the mod el and run in RADIOSS and run in RADIOSS 1. Using File > Export > Solver Deck export the model making sure to check the Auto export engine file bolted_cantilever_inacti1000_0000.rad . 2. Start HyperWorks Solver Run Manager program by selecting RADIOSS from the HyperWorks menu. 3. Submit an initial run using 4 cores by specifying –np 4. Make sure the Use solver cont rol option is checked. 4. Note that a larger than normal amount of mass scaling is used make the simulation run faster.


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5. While the model is running use a text editor to edit the bolted_cantilever_inacti1000_0000.out file and search WARINING to find the WARNING : INITIAL PENETRATIONS IN INTERFACE message. Notice the message printed right before the warning saying, INITIAL PENETRATIONS WILL BE IGNORED .

EXPECTED RESULTS, Inacti=1000

By default TYPE24 contact ignores a ll initial penetrations except for very numerical small penetrations. The initial penetrations between the top of the plate and bottom of the bolt head cause the plate to slip through the bolt and contact the next row of bolt elements.

Step 8: Check for Initial intersections to better understand con tact behavior 3. From drop down Mesh menu > Check > Components > Penetratio n 4. Using the Comps entity selector pick all three parts in the model and click check

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5. In the Penetration tab click on plate as shown in the next image. To isolate the intersecting element pick the other two options shown in the next image.

2

3

1

6. Use the display mode icon, see the intersecting elements.

, to change to wireframe mode and rotate the model to

7. In the lower right core of the Penetration tab

Click the close icon.

Step 9: TYPE24 option INACTI=-1, initial penetrations will be taken into account. 1. Although we could manually translate the nodes to remove this initial penetration, we can also use the INACTI option in to cause RADIOSS to apply forces based on the amount of initial penetration. 2. Under Groups select self contact and change to Inacti= -1 which will cause RADIOSS to apply contact forces at t=0.0 if there are intersections.

Step 10: Export t he model and run in RADIOSS 1. Following the same instructions as before export the bolted_cantilever_inacti-1_0000.rad and run RADIOSS.


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2. While the model is running use a text editor to edit the bolted_cantilever_inacti-1_0000.out file and search WARINING to find the WARNING : INITIAL PENETRATIONS IN INTERFACE message. Since all the initial penetration are taken into account there is no message saying they will be ignored.

EXPECTED RESULTS, Inacti=-1 Step 11: Plot the contact f orces 1. Load the h3d in HyperView and change to wireframe view, 2. Click on the vector plot icon /Normal (v) and click on Appl y.

and change the Result type: Contact / Pressure

Due to Inacti=-1 being used, RADIOSS applies contact forces at t=0.0 proportional to the amount of initial penetration. These forces can sometimes remove the initial penetration between the parts. 3. Change back to shaded elements mode, , and then use the contour panel to plot Result type: Von Mises(s) with Av eragin g method: Simp le and notice the stress on in the parts before any load is applied due to the initial penetration. If desired use the section cut, to create a section cut.

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4. Change the simulation time to t=5.0 which is right before the concentrated forces are applied and notice the initial stress in the bolt as shown in the following figure.

5. Animate the model to the end of the simulation and review, Von Mises(s), Displacement (v) and Plastic Strain (s)

Step 12: TYPE24 optio n INACTI=5, the master segment i s shift ed by the initial penetration value. 1. Under Groups select self contact and change to Inacti= 5 which will cause RADIOSS to apply contact forces at t=0.0 if there are intersections. This will cause RADIOSS to offset the master segment by the penetration value. The contact will now behave as though the elements with initial penetrations at t=0.0 are touching but without any contact force.

Step 13: Export bolted_cantilever_inacti5_0000.rad and r un i n RADIOSS 1. While the model is running use a text editor to edit the bolted_cantilever_inacti5_0000.out file and search WARINING to find the WARNING : INITIAL PENETRATIONS IN INTERFACE message. Notice even though the message says that the penetrations will be ignored the master


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segments is actually offset to remove the initial penetrations. This warning message will be improved in a future version of RADIOSS.

EXPECTED RESULTS, Inacti=5 Step 14: Plot the contact f orces and str ess and compare to Inacti=-1 results. 1. Repeat steps described as before to display the vector contact force at t=0.0.

With Inacti= 5, there are no contact forces at t=0.0. 2. Repeat steps described as before to plot the cross section Von Mises(s), at t=5.0 3. Repeat steps described as before and review Von Mises(s), Displacement (v) and Plastic Strain (s). 4. Last, use a text editor to edit the *0001.out engine output files for the 3 simulations and compare the %Energy Error. The simulation that used Inacti= - 1 had a higher %Energy Error caused by the application of the initial contact

forces at t=0.0.

Step 15: Optional: pl ot and com pare the bolt c ross forces of t he three models. Step 16: Optional: plot and comp are the contact and total energy of t he three models.

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Chapter 7: Kinematic Condition Exercises

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Exercise 7: Three Point Bending Objectives



Learn about kinematic conditions: boundary conditions, /BCS and rigid bodies, /RBODY Define time history output for interfaces This exercise demonstrates how to set up 3-point bending model with symmetric boundary in Y.



UNITS: Length (mm), Time (s), Mass (ton), Force (N) and Stress (MPa)



Simulation time: in Engine file 7.0e-002 s



Only one half of the model is modeled because it is symmetric.



The supports are fixed & an imposed velocity of 1000 mm/s Z - applied on the Impactor



Model size = 370 mm x 46.5 mm x 159 mm

 

Honeycomb Material /MAT/LAW28: HONEYCOMB = 3.0e-10 ton/mm

3

Eij = 200 MPa

[Rho_I]

Initial density

[E11], [E22] and [E33]

Young’s modulus

Gij = 150 MPa [G11], [G22] and [G33] Elasto-Plastic Material /MAT/LAW36: Inner, Outer and Flat 3

= 7.85-09 ton/mm [Rho_I] E = 210000 MPa [E] = 0.29 [nu] Elastic Material /MAT/PLAS_JOHNS: Impactor = 8e-09 ton/mm E = 208000 MPa = 0.29 Stress-Strain Curve:

3

Shear modulus Initial density Young’s modulus Poisson's ratio

[Rho_I] [E] [nu]

Initial density Young’s modulus Poisson's ratio

0

1

2

3

4

5

6

7

8

9

STRAIN

0

0.010

0.013

0.015

0.020

0.025

0.030

0.035

0.040

0.045

STRESS

300

310

320

330

340

350

360

370

380

400

Problem Setup Copy the file: BENDING_0000.rad to a working directory. 80 Intro to RADIOSS for Impact Analysis Proprietary Information of Altair Engi neering, Inc.

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Step 1: Import BENDING_0000.rad into HyperMesh. Step 2: Create a law 1 elastic m aterial named Rigid Material and assign to the Impactor and Support parts

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Step 3: Create a Piecewise Linear law 36 material n amed Shell Material and assign for Inner, Outer, and Flat parts 4. Create the material stress-strain curve by right-clicking on the Curve section of the model tree in the Model Browser and select Create from the context-sensitive menu to bring up the Curve Editor . 5. Select New…, enter StressStrain for the name of the new curve, and click proceed to return to the Curve Editor . 6. Enter the following values in the XY values list:


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7. Create the new law 36 material as shown below, selecting the new StressStrain curve as the fct_ID for the function definition.

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8. Assign the material to the Inner, Outer, and FLAT materials.

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Step 4: Create a law 28 Honeycomb orthotr opic material named Foam and assign to the HCFoam part:

Tip: Note that functions 5-10 used in the HCFoam definition are already defined in the model.

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Step 5: Create a shell pro perty and assign to the Inner, Outer , and Flat parts

Step 6: Right-click the Shell Property in th e Property sectio n of t he Model Brows er and select Duplic ate. Rename it to Rigid Shell and assign this property to Impactor and Support .

Note: This modeling practice, where shells are used to define the surface of a rigid structure along with a rigid body, is useful for describing arbitrarily shaped rigid surfaces. In this case, the shell property can be a simple 1integration point. The property is duplicated and N set to 1.


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Step 7: Create a general soli d type 14 prop erty HCFoam and assign to the part HCFoam .

Step 8: Create a rigid s pider for the Impactor with a calculated primary node 1. From the Model Browser right-click and select Create > Component . 2. For name, enter Rigid Bodies. 3. In the entity editor set card image as none. 4. Go to 1D page, then select the rigids panel. 5. Verify that you are in the create subpanel. 6. For dependent nodes 2-n switch to comps. 7. For primary node switch to calculate node. 8. Click comps. 9. Select Impactor, then click select

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10. Click create. Do the same thing for the comps Support. You should now

have 2 rigid bodies as shown below:


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Step 9: Define three new boundary condi tion s for the model. Boundary conditio n BCI will constrain the Impactor master node in all DOFs except Tz. Boundary condition BCS will constrain the Support rigi d master no de in all 6 DOFs. Boundary condition Symmetry will constrain all nodes in t he Inner, Outer, and FLAT parts on the Y - XZ-plane in Ty, Rx, and Rz.

HyperWorks 14.0



HyperWorks 14.0

Tip: Use the view orientation YZ plane Symmetry constraint.

HyperWorks 14.0

to aid in selecting the nodes for the


Step 10: Define an imposed Z-velocity fo r the Impactor rigid master node using the Imposed-Velocity predefi ned cur ve and a Y-Scale of -1000

Note that the imposed velocity arrow in the graphics window may not correspond to the actual direction defined.

Step 11: Defin e a Type 7 contact between the Flat (Slave) and Support (Master) part s named Support Tip: In this case we choose GAPmin of 0.45 because that is half of the thinnest shell thickness. The parameter Igap of 2 gives us variable gap , INACTI of 6 will adjust the gap if any initial penetrations exist. Also, when selecting friction in contact, set to 0.1 here, the flag Iform should be set to 2 for Stiffness formulation. Hint: All of the slave nodes can be selected by component. Similarly the master segments can be chosen by selecting the corresponding component. This will generate /GRNODE/PART and /SURF/PART/EXT, respectively.


HyperWorks 14.0

HyperWorks 14.0


Step 12: Defin e a Type 7 contact between Impactor (Master) and Outer (Slave) called Imp_Outer


HyperWorks 14.0

Step 13: Define self-contact between beam com ponents Inner, Outer , and FLAT Note that all of the nodes from these three parts will be slave to all elements from these parts as master to form the self-contact definition.

HyperWorks 14.0


Step 14: Create Interface tim e his tor y 1. Right-click in the Model Browser and select Create > Output Block. 2. In the entity editor for name, enter Contact-Forces. 3. Switch the EntityIDs to groups. 4. Click groups and select the interfaces Support and Imp_Outer from the list. Click OK. 5. Right Click the outputblock Contact-Forces and choose Card Edit. 6. For VAR field, enter DEF. 7. Click return to exit the panel.

Step 15: Select the Delete Unused dialog box by goin g to Tools > Unused and review the model to determine that all properties and m aterials are assigned. Tip: This dialog only displays entities within the model which are unassigned through reference in other entities and can be a quick way to determine if there are curves, groups, properties, or materials which are u nassigned.


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Step Step 16: Use Use the Engine File File Assi stant to define the engine keywords as show n below.

Step 17: Export the file as 3PBENDING_0000.rad and and r un in RADIO RADIOSS SS Step Step 18: 18: Review Review the output fi les for thi s run and view the results in HyperView HyperView




von Mises (Max) Stress Contour (MPa) – Only steel parts shown

Plastic Strain (Max) Contour – Only steel parts shown

100 100 Intro to RADIOSS RADIOSS for Impact Analysis Proprietary Information of Altair Engi neering, Inc.


von Mises Stress (Mid) Contour (MPa) – Only foam shown

Step Step 19: Plot Plot a graph of the Z-normal forc e resultant over time fr om th e Imp_Outer interface from the file 3PBENDINGT01 usin g HyperGraph HyperGraph

Contact Force for Impactor Interface

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Intro to RADIOSS RADIOSS for Impact Analys is 101 Proprietary Information of Altair Engi neering, Inc.

Chapter 9: Timestep Control Exercises


HyperWorks 14.0

Exercise 9: Time Step Control on Bottle Top Load Simulation Objectives Become familiar with options for improving time step which will reduce the solution time of your simulation. This exercise demonstrates how to set up a bottle top load simulation and evaluate different time step control treatments. The bottle is loaded using a rigid plate. A 0.25 inch imposed displacement is applied to the plate.

Model Descripti on 

UNITS: Length (mm), Time (ms), Mass (Mg), Force (N) and Stress (MPa)



Simulation time *_0001.rad [0 – 0.03 seconds]




o The rigid plate applying the load is fixed except for the imposed displacement in the vertical direction

o The bottom of the bottle is supported by a rigid wall o A 0.25 inch imposed displacement is applied to the rigid plate 

Objective is to calculate the max top load for bottle.

Input files for this tutorial: bottle_timestep_0000.rad, bottle_timestep_0001.rad

Materials Elastic Plastic Piecewise Linear Material /MAT/LAW36 (Bottle)    

-10

= 9.75e

E = 800.0 MPa = 0.4 fct_ID1

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3

Mg/mm

[Rho_I] Initial density [E] Young’s modulus [nu] Poisson’s ratio

Yield stress function

Intro to RADIOSS for Impact Analys is 103 Proprietary Information of Altair Engi neering, Inc.

Properties

Exerci se 9a: Evaluate the Time Step and review the Model Purpose: Use various methods to determine the time step of a simulation and impr ove the time step by modif ying elements Step 1: Load and review the RADIOSS Model 1. Launch HyperMesh, then select Preferences > User Profil e > BRADIOSS Block140 2. From the pull down menu bar, File > Import > Solv er Deck 3. Click the icon, navigate to the directory with the starting file and select the initial model bottle_timestep_0000.rad

4. Using the Model Browser, review the material properties, shell prop erties, contact, rigid wall, and boundary conditions. The top load is applied using an imposed displacement applied to a rigid meshed plate. The bottom of the bottle is supported by a rigid wall, /RWALL.

Step 2: Review Engine File and make ini tial run 1. In Model Browser, Card > ENG_ANIM_NODA > notice that DT is checked which creates the following output request that will allow the contouring of the nodal time step in HyperView. Alternatively, text editor could be used to review the bottle_timestep_0001.rad. /ANIM/NODA/DT

Contour output for Nodal Time step


HyperWorks 14.0

2. Start HyperWorks Solver Run Manager program by selecting RADIOSS from the HyperWorks menu. 3. Submit an initial run using 4 cores by specifying –np 4. Make sure the Use solver cont rol option is checked.

4. Notice the low time step, DT = 4.41E-08, and the long estimated remaining solution time, REMAINING TIME= 3566.03 s . Note: this number will vary depending on the speed of the computer and the number of CPUs used for the solution. 5. Stop the run by checking the Stop checkbox and selecting Send Comm and then Close

6. Using a text editor open the bottle_timstep_0001.out and find the section that shows the run cycles. Notice that it says that SH_3N (a tria element) element number 9279 is controlling the time step.

Next we will use a few different methods to find the time step of the whole model

Step 4: Find Nodal Time step in output fil e 1. Using a text editor open the bottle_timstep_0000.out 2. Use Find in the text editor to search for “time step” in the file. Notice that the time step is listed for each element type and along with a nodal time step estimation.

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Notice that there are 3 shell (quad) and 2 triangular elements with a low time step of ~ 5e-8. These are the elements that are controlling the time step.

Step 5: Contour Plot time step with HyperView The engine output option /ANIM/NODA/DT allows us to contour plot the nodal time step

1. Start HyperView then File > Open > Model and click the the bottle_timstepA001. 106 Intro to RADIOSS for Impact Analysis Proprietary Information of Altair Engi neering, Inc.

and select

HyperWorks 14.0

2. Turn off the parts bottom plate and load applicator as shown in the next image.

3. Select the contour icon,

and select Resul t ty pe: Time Steps (s) click Apply

4. Press the “M” key to turn on the mesh. 5. Rotate the model to find the location with the low time step which will be dark blue by default. Zoom in to see that some very small elements are causing the small time step

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Note that typically elements with small edges cause low time steps. Both HyperMesh check elems or HyperCrash Quality, Check Elements of Tree Selecti on can also plot an estimation of the time step of elements. 6. In HyperMesh, press F10 for the Check Elems panel, toggle the Time 7. Set the time step for all types: 1.0e-7, and click check elems, then save failed 8. To isolate the elements that failed, press F5, for the Mask panel click elems, retrieve; elems, by adjacent; elems, reverse; then the green mask button 9. Zoom in and find the 5 small thin elements that are controlling the timestep. 10. To delete the small elements, press F2 for the delete panel. 11. Select the 5 small elements and click delete entity , then return 12. Access the Edges panel by Pressing SHIFT+F3 keys 13. With comps entity selector highlighted click once on an element on the screen 14. Enter tol erance = 0.1 and click preview equiv to see the nodes that will be equivalence 15. Click equivalence to equivalence the nodes

16.Select File > Expor t > Solver Deck and click bottle_element_0000.rad click Export

enter

NOTE: The engine file bottle_element_0001.rad will automatically be created if Auto export engi ne file is checked.

Exercise 9b: Run Simul ation with Default Element time step Purpose: Run updated model using th e default element time step calculated by RADIOSS. 1. Start HyperWorks Solver Run Manager program and submit an initial run using 4 cores by specifying –np 4 . Make sure the Use solver cont rol option is checked. 1. Using a text editor open the bottle_element_0000.out 1. Use Find in the text editor to search for “time step” in the file and n otice that the time step is now much higher listed for each element type and the nodal time step. 2. Compare the smallest element time step listed in the bottle_element_0000.out file to the time step listed in the output while the model is running or in the bottle_element_0001.out file. Why are they not the same? 3. After the solution has finished, look at the end of bottle_element_0001.out for ELAPSED TIME = ________________ . 4. Start HyperView and use File > Open > Model to load the bottle_element.h3d file. 108 Intro to RADIOSS for Impact Analysis Proprietary Information of Altair Engi neering, Inc.

HyperWorks 14.0

5. Select the contour icon, and select Result type: Stress (t): vonMises to create a contour plot of the stress of th e crushing bottle in HyperView.

6. Animate the bottle crush by clicking on the animate button on the toolbar, Next click File > Open > Report Templ ate, and select the report template file force_displacement.tpl Click on PLOT_FILE_1 and select the file open icon and select the bottle_elementT01. Last click App ly and a second page will be added to HyperView with the force displacement plot of th e load applicator as shown below. 7. Save a HyperView session file of these results, on File >Save > Session enter the name bottle_results.mvw and click save.

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Exerci se 9c: Run Simul ation wi th Nodal time step Purpose: Re-run the model usin g a constant nodal tim e step to reduce total run tim e RADIOSS. 1. Copy the bottle_element_0000.rad and bottle_element_0001.rad files to bottle_nodal1_0000.rad and bottle_nodal1_0001.rad into the new directory. 2. Using a text editor and open bottle_nodal1_0001.rad to add the following Engine Control Card to enable nodal time step calculation. /DT/NODA/CST 0.67 2.0e-6 /ANIM/NODA/DMAS NOTE: The above command will cause RADIOSS to use the nodal method of calculating the time step. The 0.67 is the time step scale factor while 2.0e-6 is the minimum constant time step (CST) that will be used by the RADIOSS simulation. This /DT/NODA/CST option will cause RADIOSS to add mass to any node whose time step is less than 2.0e-6 / 0.67 ≅ 3.0e-6. When mass is added to a node its time step increases. /ANIM/NODA/DMAS causes RADIOSS to create a contour output of the, change in mass / original mass. 3. As before, start the HyperWorks Solver Run Manager and start running the bottle_nodal1_0000.rad file using 4 cores. 4. Observe the amount of mass added in the last column of the bottle_nodal_0001.out simulation by text editing the bottle_nodal_0001.out file. This MAS.ERR is the (change in mass) / (original mass). To get % mass added multiply this number by 100. So in this simulation 117.4% mass has been added which is too much.

NOTE: Good engineering judgement must be used to determine how much mass is an acceptable amount to be added to a model to reduce the runtime. Adding too much mass can affect the physics of a drop or impact simulation. This is because the object being simulated weighs more than the real part. In general it is recommended to keep the amount of mass added to less than 5% but more may be acceptable depending on a particular simulation.

5. Click on the Open Report Panel Icon to plot the force displacement curve for the nodal time step. Click beside the PLOT_FILE_1 and pick the


HyperWorks 14.0

bottle_nodal1T01 file. Uncheck “Use report colors” and select “Overlay” under Mode and click App ly . 6. Compare the force displacement (f-d) curves of the two models. Adding too much mass combined with the relatively fast loading time makes maximum force larger.

8. In HyperView click on the add page icon

and add another HyperView page.

9. If needed, change the page type from HyperGraph 2D to HyperView using the icon 10. Click on the new empty window and use File > Open > Model and the select the bottle_nodal1.h3d file and click App ly . 11. Select the contour icon, and contour plot Mass Change (s) which is the (change in nodal mass) / (original nodal mass). It is always good to understand where the mass is being added in your model. It can be important to minimize the amount of mass is added to critical areas of the design. 7. Did the amount of mass added by using a time step of 2.0e-6 cause a large difference in the results compared to the results from the first simulation with elemental time step? 8. Copy the files to bottle_nodal1_0000.rad and bottle_nodal1_0001.rad files to bottle_nodal2_0000.rad and bottle_nodal2_0001.rad 12. Determine a time step that adds less mass by editing the bottle_noda11_0000.out RADIOSS starter output file and searching for the NODAL TIME STEP. Starting with the

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smallest time step determine where the time step of the nodes doesn’t increase very much more and then use that as your /DT/NODA/CST time step. 13. Run the model and see how much % mass was added. Experiment until you find a time step that limits the mass added to ≤ 5% (i.e. MAS.ERR ≤ 0.05) 14. How much % mass was added _________ _____.? 15. In same HyperView session that contained the element time step results, switch to the first page that contained the element time step contour plot by using

.

16. Change page to bottle_element.h3d results and change to two windows using this icon, to 17. Click on the new empty window and use File > Open > Model and the select the bottle_nodal2.h3d file and click App ly . 18. Select the contour icon, and select Result type: Stress (t): vonMises to create a contour plot of the stress of th e crushing bottle in HyperView. 19. How does the stress results compare to the f irst simulation with element time step?

20. Click on the Open Report Panel Icon to plot the force displacement curve for the nodal time step. Click beside the PLOT_FILE_1 and pick the bottle_nodal2T01 file. Uncheck “Use report colors” and select “Overlay” under Mode and click Apply. 21. How does the top load force results compare to the other two simulations? 22. After the solution has finished, look at the end of bottle_nodal2_0001.out for ELAPSED TIME = ________________ . 23. How much faster does this nodal time step with mass scaling compared first run with element time step ______________?

Exercise 9d: Run Simulatio n with Advance Mass Scaling (AMS) Purpose: Run the model usi ng the Advanced Mass Scaling (AMS) method to furth er reduce run time. The load needs to be applied slower to get a converged quasi-static maximum top l oad force and remove vibrations in the force displ acement curve. By using AMS with a higher time step and apply the load over a longer time, a converged quasi-static maximu m top load force can be calculated. 1. Launch HyperMesh, then select Preferences > User Profil e > BRADIOSS Block140 2. From the pull down menu bar, File > Import > Solv er Deck


HyperWorks 14.0

3. Click the icon, navigate to the directory with the starting file and select the initial model bottle_element_0000.rad 4. Next select Tools > Create Cards > AMS. This option lets you specify a part group AMS will be applied to. If no part group is specified then AMS is applied to the whole model.

5. 6. Next select Tools > Create Cards > ENGINE KEYWORDS > DT > DT/ Tscale=0.67, TMIN=1.0E-5 NOTE: The above options will cause RADIOSS to use the Advance Mass Scaling (AMS) method to increase the time step. With AMS, the added mass does not increase the translational kinetic energy of the system. See Advanced Mass Scaling (AMS) Guidelines in the RADIOSS help for more details. Due to the way AMS changes the mass matrix, high frequencies are damped out of a system. This makes AMS best used for quasi static or low speed simulation where the high frequency spectrum is not important to the re sults. Experience has shown that a good starting time step for an AMS simulation is 10x the minimum NODAL TIME STEP from the starter output f ile or 10x a valid /DT/NODA/CST simulation’s time step. To eliminate the vibrations in the force deflection curve, the load needs applied 10X slower. 9. In Model B rowser > L oad Collector, click on 3disp and enter scale_x=10. This apply a scale factor of 10x to the abscissa so the load will be applied from 0 – 0.3 seconds. 10. In Model Browser > Card click on ENG_ANIM_DT and enter, Tfreq=0.03 to that 10 animation files are created in 0.3 seconds of run time. 11. In Model Browser > Card click on ENG_RUN T_STOP=0.3 so that the simulation ends at 0.3 seconds. 12. Select File > Expor t > Solver Deck and click Export

enter bottle_ams_0000.rad click

13. As before, start the HyperWorks Solver Run Manager and start running the AMS model bottle_ams_0000.rad using 4 cores by specifying the option –np 4. 14. Compare the total run time to the other simulations. 15. Switch to the first page that contained the element time step contour plot and n odal time step contour plot change the page to three windows using this icon, 16. Click on the new empty window and use File > Open > Model and the select the bottle_ams.h3d file and click App ly. 17. Select the contour icon, and select Result type: Stress (t): vonMises to create a contour plot of the stress of th e crushing bottle in HyperView. 18. How does the stress results compare to the first simulation with elemen t time step?

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19. Click on the Open Report Panel Icon to plot the force displacement curve for the nodal time step. Click beside the PLOT_FILE_1 and pick the bottle_amsT01 file. Uncheck “Use report colors” and select “Overlay” under Mode and click Apply. NOTE: To reduce run solution time, the top load was applied faster than the actual test. To determine the effect of this faster loading time, a good engineering practice would be to apply the load slower to converge on a maximum top load force in the simulation. Using AMS to increase the time step, allows the load to be applied slower and results still be obtained in a reasonable amount of time. 20. The AMS force deflection curves are smoother then element and nodal results because the load was applied slower resulting in less dynamic affects. The AMS maximum top load force is very close to the converge d quasi-static force of 205 N.


HyperWorks 14.0

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Capstone Exercises


HyperWorks 14.0

Capstone: Cell Phone Drop This capstone project is of a cell phone drop. Many parts of the phone are already connected. Often, this type of analysis would be done with second order tetrahedral elements. The model supplied is first order to save computation time. Your task is to review the model for completeness and finish the model setup using the information below to get a valid simulation.

Problem Probl em Setup Setup Copy the files: phonedrop_start_0000.rad to a working directory.



Front cover Windo w and Touch sensor Gaske t Button s LCD module Carrie r PCB Batter y Frame Screw s

Back cover with logo

Complete Connections Connections and Contact The screws need to be connected to the front cover. 0.2. Assume the parts interact interact with each other with a friction value of 0.2.

Loading Conditions 1.5 meters in the Z-direction to Z-direction to a flat floor on the Z plane. plane. The phone drops from a height of 1.5 meters The forces between the phone and the flo or need to be recovered. The total simulation time is 1 millisecond. Animation output requests should include plastic strain for solids and shells, vonMises stress, tensor of shell membrane stress, and nodal added mass.



Run Analysis and Post -Process -Process Run the simulation and post-process the results, comparing to the results on the following page. L ook at the force between the phone and the floor as a function of time. Com pare with the weight of the phone at rest.




Displacement and VonMises Stress Results


HyperWorks 14.0

Capstone: Bumper Impact This capstone project is of a bumper hitting an offset wall. The parts are completely modeled. Your task is to review the model for completeness and finish the model setup using the information below to get a valid simulation.

Front Rail

Crush Box

Bumper Beam

Problem Setup Copy the files: bumper-start_0000.rad to a working directory.

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Property and Material Inform ation The component thickness and material is shown below: Part Name

Thick ness

Material

Bumper Beam

2.5

Aluminum

Crush Box

2.5 mm

Aluminum

Front Rail

4.2 mm

High Strength Steel

Connections The Crush Box is connected to the Bumper B eam with a MIG Weld along the top and bottom flanges (4 places). Green box shows one location.

The Crush Box is attached to the Front Rail with bolts of diameter 10 mm (8 places). Red circle shows one location.

The Truc k Frame The rear part of the truck frame has a value of mass of 1400 kg, with rotational in ertias (Ixx, Iyy, Izz) that can be assumed to be 2.0e6. The mass’s location is (2000, 0, 170).

Impact Conditions 

The bumper impacts a finite sized wall centere d at (-503.5, -425, 180) that is 240 mm high by 560 mm wide. Assume friction of 0.2.



The initial velocity of the frame is 4.5 mm/msec.



Assume all the parts have a friction coefficient of 0.2



The total simulation time is 30 milliseconds


HyperWorks 14.0



Section forces need to be recovered for the left Front Rail and one for the right at x= -270.

Run Analysis & Post-Process Run the simulation and post-process the results, comparing to the results on the following page. Results of interest include: 

Deformation



Global Energies – Kinetic, Internal, Contact, Total



Vehicle CG deceleration



Rigid Wall forces



Section forces – Left and Right Rails

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Bumper Results


HyperWorks 14.0

Appendix A: Using RADIOSS with HyperStudy 1- HyperStudy Altair HyperStudy is multi-disciplinary design study software that enables exploration and optimization of design performance and robu stness. The design of the tool as a wizard makes it very easy to learn and use. It is applicable to study the different aspects of a design under various conditions, including non-linear behaviors and multi-disciplinary applications. The models can be parameterized very easily. Besides the typical definition of solver input data as design variables, the shape of a finite element model can also be parameterized with ease. HyperStudy Post-Processing module contains display, analysis and data mining capabilities that helps engineers to overcome the challenging task of extracting relevant information from multi-run studies. With its unique and powerful suite of tools, simulation results can be analyzed, sorted and studied effectively in HyperStudy. Specifically developed for design of experiments (DOE), fit (metamodelling), optimization and stochastic studies, HyperStudy users can: o Gain insight into the physics of a design o Assess the robustness of a design for controlled or uncontrolled variations in the design parameters o Optimize a design for multi-disciplinary attributes

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2- HyperStud y Benefits 9. Provides engineers with an easy way to study effects of design changes for complex analysis events; 10. Allows engineers to assess the robustness of designs and provides the guidance necessary to achieve robust designs; 11. Allows engineers to perform multi-disciplinary optimization studies for different attributes of a design; 12. Allows engineers to perform system identification and correlation studies of designs; 13. Allows engineers to perform validation and evaluation of models and results using the Evaluation and Rating module; 14. Complements existing CAE software with added functionality and direct interfaces to maj or solvers; 15. Minimizes time-to-market by identifying design direction for difficult problems 16. Reads CAE native data files: RADIOSS, MotionSolve, OptiStruct, LS-DYNA, NHTSA ABF, MADYMO, PAMCRASH, NASTRAN, ABAQUS, ADAMS, DADS, SIMPACK and others.

HyperStudy Interface


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HyperStudy Process HyperStudy process is composed of two major steps: Study Setup and Study Approaches. In Study setup, the analysis process is automated and in study approaches, this process is repeated many times depen ding on the study objectives.

HyperStudy Overview

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Study Setup Study setup compromises of: parameterization, model definition and evaluation, response extraction. HyperStudy has two ways of design parameterization. First one, parametrizing an input deck, is generic but can be involved at times. Second one, working on the HyperMesh model, is more specific but very easy to use. Any ASCII input deck can be parametrized using HyperStudy’s editor. In the case of FEA models, direct linking to Hypermesh provides HyperStudy direct access to simulation models and to the features such as thickness, concentrated masses, shape changes which are used as the design variables in DOE, optimization or stochastic studies. HyperMorph is integrated for shape parameterization.

For response extraction, HyperStudy uses HyperGraph readers and hence any result that can be read by HyperGraph can also be read by HyperStudy. HyperStudy can also extract any value from an ASCII output file.


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Study Approaches There are four study approaches in HyperStudy. They are: Design of Experiments (DOE), fit, optimization and stochastics. The objective of a DOE, or Design of Experiments, study is to understand how changes to the parameters of a model influence its performance. In such a study, a model is repeatedly run through a simulation for various combinations of parameter settings. Effects and interactions of the design variables of the model can be studied. From a DOE, mathematical models can be built describing the responses of the model as an algebraic or numeric function of its parameters. This function is an approximation of the true response. The algebraic or numeric expression that describes the response of a model as a function of the parameters is known as a response surface. Once a set of response surfaces have been generated for a model, those response surfaces can act as a proxy for the model. New combinations of design variable settings not used in the original design can be plugged into the response surface equations to quickly estimate the response of the model without actually running the model through an entire analysis. Optimization studies are used to find the parameter setting of a model that minimizes or maximizes a particular objective function subject to a number of design constraints. A special form of optimization problem, called System Identification, can also be solved in an optimization study. In this case, the objective function is to minimize the quadratic deviation of a given function from a target function. Optimization can be applied simultaneously to any one or more analysis codes and hence can be multi-disciplinary. Size and shape optimizations can be performed. The optimization can be performed using the analysis solver directly, or using a response surface created in a DOE study. Stochastic studies are used to study the influence of statistical distribution in the design variables on the responses of a design. The stochastic analysis can be performed using the analysis solver directly, or using a response surface created in a DOE study.

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Exercise A1: Material Calibration Using System Identification The purpose of this tutorial is to introduce a method for characterizing parameters of a RADIOSS material law used for modeling elasto-plastic material. The characterization of a ductile aluminum alloy is studied. A RADIOSS simulation is performed to replicate an experimental tensile test. The parameters of the material law are determined to fit the experimental results. A quarter of a standard tensile test specimen is modeled using symmetry conditions. A traction is applied to a specimen via an imposed velocity at the left-end. Geometry of the Tensile Specimen (One Quarter of the Specimen is Modeled)

Sections of Node Saved for Time History

The material to be characterized is a 6063 T7 Aluminum: it has an isotropic elasto-plastic behavior which can be reproduced by a Johnson-Cook model without damage (RADIOSS Block Law2), defined as follows:


HyperWorks 14.0

In this study we define, as design variables, the parameters a, b, n, σmax (maximum stress) and the Young modulus. The stress-strain curve obtained by the experimental test is shown in the following image.

Engineering Stress Versus Engineering Strain Curve (Experimental Data)

For the simulation results, engineering strains will be obtained by dividing the displacement of node 1 by the reference length (75 mm), and engineering stresses will be obtained by dividing the force in section 1 by its initial surface (12.012 mm2).

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Engineering Stress Versus Strain Curve (Simulation Results)

In this tutorial, you will:   

Create an input template from a RADIOSS data file using the HyperStudy Template Editor Set up a study Run a system identification optimization study

Problem Setup You will need to copy the files: TENSILE_TEST_0000.rad, TENSILE_TEST_0001.rad, and exper.xy


HyperWorks 14.0

Step 1: Create the Base Input Template in HyperStudy 1. Start HyperStudy . 2. From the menu bar, click Tools > Editor . The Parameter Editor opens. 3. In the File field, navigate to your working directory and open the TENSILE_TEST_0000.rad file.

Tip: RADIOSS uses fixed fields of 20 characters per field for properties. 4. In the Search area, enter /MAT/PLAS_JOHNS/1 and click

to run the search..

HyperStudy highlights /MAT/PLAS_JOHNS/1 in the TENSILE_TEST_0000.rad file.

5. Select E, the Youngs Modulus value, by starting at the beginning of row 51 and highlighting the first 20 fields.

Tip: To assist you in selecting 20-character fields, press CTRL to activate the Selector (set to 20 characters) and then click the value.

6. Right-click on the highlighted fields and select Create Parameter from the context sensitive menu. 7. In the Parameter Varname_1 dialog, enter E_Young in the Label field. 8. Set the Lower Bound to 50000, the Initial Bound to 60400, and the Upper Bound to 70000. 9. In the Format field, enter %20.5f.

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10. Click OK . 11. To define four more variables, repeat steps 1.4 through 1.11 using the information provided in the table below.

Tip: Some of the initial values are different from the values in the original file. Variable

Label

Lower Bound Initial Value Upper Bound

Format

a

_PlasticityYieldStress

90

110

120

%20.5f

b

_HardeningCoeff

100

125

160

%20.5f

n

_HardeningExpo

0.1

0.2

0.3

%20.5f

250

280

290

%20.5f

sigmax

igma_Max

12. Click Save. 13. In the Save Template dialog, navigate to your working directory and save the file as

TENSILE_TEST_0000.tpl. 14. Close the Parameter Editor dialog.

Step 2: Perform t he Study Setup 1. To start a new study, click File > New from the menu bar, or click

on the toolbar.

2. In the HyperStudy – Add dialog, enter a study name, select a location for the study, and click

OK . 3. Go to the Define models step.


HyperWorks 14.0

4. Add a Parameterized File model. a. From the Directory, drag-and-drop the TENSILE_TEST_0000.tpl file into the work area.

b. In the Solver input file column, enter

TENSILE_TEST_0000.rad;TENSILE_TEST_0001.rad. This is the name of the solver input file HyperStudy writes during any evaluation. c.

In the Solver input file column, select RADIOSS (radioss).

d. In the Solver input arguments column, enter -both at the end of $file.

Tip: This argument runs the Starter, and the Engine of RADIOSS for the crash analysis. It also prevents the creation of the .h3d result file from animation files. X is the number of CPUs to use for the simulation.

5. Click Import Variables. Five design variables are imported from the

TENSILE_TEST_0000.tpl resource file. 6. Go to the Define design variables step. 7. Check the design variable's lower and upper bound ranges. 8. Go to the Specifications step.

Step 3: Perform the Nominal Run 1. In the work area, set the Mode to Nominal Run. 2. Click Apply . 3. Go to the Evaluate step.

HyperWor ks 14.0


4. Click Evaluate Tasks.

Tip: An approaches/nom_1/ directory is created inside the study directory. The

approaches/nom_1/run__00001/m_1 directory contains the TENSILE_TESTT01 file, which stores the time history results of the simulation. 5. Go to the Define response step.

Step 4: Create and Defin e Respo nses Tip: To fit the RADIOSS stress-strain curve to the experimental data in this tutorial, three specific points per curve will be compared. Since damage is not modeled with this law, the comparison is not needed after the necking point. 

Difference between experimental stress and RADIOSS at Strain equal 0.02 (1)



Difference between experimental strain and RADIOSS at Necking point (2)



Difference between experimental stress and RADIOSS at Necking point (3)

1. Click Add Response.


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2. In the HyperStudy - Add dialog, add three responses labeled: Radioss_Strain_0_2,

Radioss_Stress_Necking, and Radioss_Strain_Necking. 3. In the Expression column of the response Radioss_Strain_0_2 , click

.

4. In the Expression Builder, click the File Sources tab. 5. Click Add File Source. 6. In the HyperStudy - Add dialog, add one Solver output file labeled Disp_sim.

6. In the File column of Disp_sim , click

.

7. In the Vector Source dialog, navigate to the approaches/nom_1/run__00001/m_1 directory and open the TENSILE_TESTT01 file. 8. From the Type, Request, and Component fields, select the options indicated in the image below.

9. Click OK . 10. Repeat steps 4.5 through 4.8 to add a second vector labeled Force_sim. HyperWor ks 14.0


11. From the Type, Request, and Component fields, select the options indicated in the image below.

12. Click OK . 13. Click the Function tab. 14. From the list of functions, select lininterp. 15. Click Insert Varname. The function lininterp() appears in the Evaluate Expression field. 16. In the Evaluate Expression field, enter (v_1/75,v_2/12.012,0.02) in the lininterp function.

Tip: This expression computes the Stress with respect to the Strain, at Strain equals 0.02.

17. Click Evaluate Expression. 18. Click OK . 19. In the Expression column of the response Radioss_Stress_Necking, click

.

20. In the Expression Builder, click the Functions tab. 21. From the list of functions, select max. 22. Click Insert Varname. The function max() appears in the Evaluate Expression field. 23. In the Evaluate Expression field, enter

(v_2[subrange(v_1,min(v_1),v_1[indexofmax(v_2)])])/12.012 in the max function.


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Tip: This is the maximum of the force ( v_2), which is trimmed between the m in strain and the strain at the max value of Force, For ce, divided by 12.012 (surface) to obtain the stre ss.

24. Click Evaluate Expression. 25. Click OK . 26. In the Expression column of the response Radioss_Strain_Necking, click

.

27. In the Evaluate Expression field, enter

v_1[maxindex(subrange(v_1,min(v_ v_1[maxindex(subrange(v_1,min(v_1),v_1[indexofma 1),v_1[indexofmax(v_2)]))]/75 x(v_2)]))]/75. Tip: This is the displacement (v_1) at the max value of t he force value, divided by 75 to obtain strain.

28. Click Evaluate Expression. 29. Click OK .

Step Step 5: Run an Optimi zation zation Study 1. In the Explorer, right-click and select Add Approach Approach from the context menu. 2. In the HyperStudy - Add dialog, select Optimization and click OK . 3. Go to the Select design variables step. 4. Review the design variable's lower and upper bound ranges. 5. Go to the Select responses step. 6. Click Add Objective. 7. In the HyperStudy - Add dialog, add three objectives labeled: Radioss_Strain_0_2,

Radioss_Stress_Necking, Radioss_Strain_Necking. 8. Define the three objectives by selecting the options indicated in the image below from the Type,

Apply On, and Target Value columns.



9. Click Apply . 10. Go to the Specifications step. 11. In the work area, set the Mode to Adaptive Response Surface Method (ARSM).

Tip: Only the methods that are valid for the problem formulation are enabled. 12. Click Apply . 13. Go to the Evaluate step. 14. Click Evaluate Tasks to launch the optimization. 15. Click the Iteration Plot 2D tab. 16. Using the Channel selector, select the three objectives from and the Objective Function Value. Activate multiplot to to see the each e ach channel in its own plot.

Tip: The first three selections are the actual values used in the system identification optimization problem. Observe their objective history to see that their values indeed approach their respective target values. The final plot is the scalar objective which is used in t he system identification problem; a normalized sum of the squares difference between t he actual and target objective values. Note that the v alue of this combined function has been reduced through the optimization.



HS-4 HS-422 220: 0: Size Size Opt Optim imiza izatio tion n Study on an Impact Simul ation Using RADIO RADIOSS SS This tutorial demonstrates how to perform a size op timization on a finite element model defined for RADIOSS. The objective is to minimize minimize the mass of the beam under the following two constraints: the internal energy must be more than 450, and the resulting reaction force must be less than 75. The design variables are the thicknesses of the four components defined in the input deck boxbeam1._0000.rad via the /PROP/SHELL entries. They are combined into two design variables. The thickness should be between 0.5 and 2.0; 2.0; the initial thickness is 1.0. The optimization optimization type is size. size.

Figure 1. Boxbeam Boxbeam mod el, undeformed



Figure 2. Boxbeam model, deformed, t = 2.001.

Problem Setup You will want to copy the files: boxbeam_0000.rad, boxbeam_0001.rad


HyperWorks 14.0

Step 1: Create the Base Input Template in HyperStu dy 1. Start HyperStudy 2. From the menu bar, click Tools > Editor . The Editor opens. 3. In the File field, navigate to your working directory and open the boxbeam1_0000.rad file. 4. In the Search area, enter /PROP/SHELL/1. 5. Click

until you find /PROP/SHELL/1.

6. Highlight the field for the thickness. Tip: To assist you in selecting 20-character fields, press CTRL to activate the Selector (set to 20 characters) and then click the value. HyperStudy highlights 20 fields.

7. Right-click on the highlighted fields and select Create Parameter from the context menu. 8. In the Parameter - varname_1 dialog, Label field, enter Upper part. 9. Set the Lower bound to 0.5, the Initial value to 1.0, and the Upper

bo und to 2.0.

10. Set the Format to %20.5f. 11. Click OK .

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12. Repeat steps 1.4 through 1.6 for the second component, /PROP/SHELL/2. 13. Assign the same thickness to /PROP/SHELL/2 as /PROP/SHELL/1 by right-clicking on the highlighted fields and selecting Attach to > varname_1 from the context menu.

14. Repeat steps 1.4 through 1.6 for the third component, /PROP/SHELL/3. 15. Right-click on the highlighted fields and select Create Parameter from the context menu. 16. In the Parameter - varname_2 dialog, Label field, enter Lower part. 17. Set the Lower bound to 0.5, the Initial

value to 1.0, and the Upper bound to 2.0.

18. Set the Format to %20.5f. 19. Click OK .


HyperWorks 14.0

20. Repeat steps 1.4 through 1.6 for the fourth component, /PROP/SHELL/4. 21. Assign the same thickness to /PROP/SHELL/4 as /PROP/SHELL/3 by right-clicking on the highlighted fields and selecting Attach to > varname_2 from the context menu. 22. Click Save. 23. In the Save Template dialog, navigate to your working directory and save the file as

boxbeam1.tpl. 24. Close the Editor.

Step 2: Option al. View the Base Input Templ ate in TextView 1. Start HyperGraph . 2. On the Client Selector toolbar, select TextView .

3. From the menu bar, click File > Open > Document . 4. In the Open Document dialog, open the boxbeam1.tpl file. The text e ditor displays the following design variables that are defined by Templex parameter statements:

{parameter(t1,"Upper part",1.0,0.5,2.0)} {parameter(t2,"Lower part",1.0,0.5,2.0)} 5. On the Text toolbar, click

.

6. In the Find dialog, Find field, enter /PROP/SHELL.

7. Click

. The parameterized /PROP/SHELL cards, which reference the design variables,

highlight.

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8. On the Text toolbar, click

. The text editor evaluates the Templex statements, and replaces

the parameters with their initial values. 9. Repeat steps 2.5 through 2.7, and se arch for /PROP/SHELL again. You will find:


HyperWorks 14.0

10. Close HyperGraph; you do not need to save the session.

Step 3: Perform the Study Setup 1. Return to HyperStudy . 2. To start a new study, click File > New from the menu bar, or click

on the toolbar.

3. In the HyperStudy – Add dialog, enter a study name, select a location for the study, and click

OK . 4. Go to the Define models step. 5. Add a Parameterized File model. a.

From the Directory, drag-and-drop the boxbeam1.tpl file into the work area.

HyperWor ks 14.0


b. In the Solver input file column, enter

boxbeam1_0000.rad;boxbeam1_0001.rad. This is the name of the solver input file HyperStudy writes during any evaluation. c.

In the Solver execution script column, select RADIOSS (radioss).

6. Click Import Variables. Two design variables are imported from the boxbeam1.tpl resource file. 7. Go to the Define design variables step. 8. Review the design variable's lower and upper bound ranges. 9. Go to the Specifications step.

Step 4: Perform the Nominal Run 1. In the work area, set the Mode to Nominal Run. 2. Click Apply . 3. Go to the Evaluate step. 4. Click Evaluate Tasks. An approaches/nom_1/ directory is created inside the study directory. The approaches/nom_1/run__00001/m_1 directory contains the result files. 5. Go to the Define response step.

Step 5: Create and Defin e Respo nses 1. Click Add Response. 2. In the HyperStudy - Add dialog, add three responses and label them Energy, Force, and

Mass. 3. In the Expression column of the response Energy, click

.


HyperWorks 14.0

4. In the Expression Builder, click the File Sources tab. 5. Click Add File Source. 6. In the HyperStudy - Add dialog, add one Solver output file.

7. In the File column of Vector 1, click

.

8. In the Vector Source dialog, navigate to the approaches/nom_1/run__00001/m_1 directory and open the boxbeam1T01 file. 9. Define Vector 1 as the internal energy of the model by selecting the options indicated in the image below from the Type, Request, and Component fields.

10. Click OK . 11. Click the Function tabs. 12. From the list of functions, select max. 13. Click Insert Varname. The function max() appears in the Evaluate Expression field. 14. Click the File Sources tab. HyperWor ks 14.0


15. Click Insert Varname. The expression in the Evaluate Expression field changes to

max(v_1[0]). 16. Remove [0] from the expression; we want the maximum of the entire vector and not just the first entry.

17. Click OK . 18. Repeat steps 5.3 through 5.8 for the response Force. 19. Define Vector 2 as the resultant reaction force in the Z-direction by selecting the options indicated in the image below from the Type, Request, and Component fields.

20. Click OK . 21. Wrap the expression in the max function and remove [0]. The expression should read,

max(v_2). 22. Insert the function max(v_2) into the Evaluate Expression field. 23. Click OK . 24. Repeat steps 5.3 through 5.8 for the response Mass. 25. Define Vector 3 as the mass by selecting the options indicated in the image below from the

Type, Request, and Component fields.


HyperWorks 14.0

26. Click OK . 27. Insert the function v_3[0] into the Evaluate Expression field. In order to extract the initial mass, do not remove the [0] after v_3. 28. Click OK . 29. Click Evaluate Expressions to extract the response values.

Step 6: Run an Optimi zation Study 1. In the Explorer, right-click and select Add Approach from the context menu. 2. In the HyperStudy - Add dialog, select Optimization and click OK . 3. Go to the Select design variables step. 4. Review the design variable's lower and upper bound ranges. 5. Go to the Select responses step. 6. Click Add Objective. 7. In the HyperStudy - Add dialog, add one objective. 8. In the Apply On column, select Mass (r_3).

9. Click the Constraint tab.

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10. Click Add Constraint . 11. In the HyperStudy - Add dialog, add two constraints. 12. Define the constraints by selecting the options indicated in the image below from the Apply On,

Bound Type, and Bound Value columns.

13. Click Apply . 14. Go to the Specifications step. 15. In the work area, set the Mode to Adaptive Response Surface Method (ARSM).

Tip: Only the methods that are valid for the problem formulation are enabled. 16. Click Apply . 17. Go to the Evaluate step. 18. Click Evaluate Tasks to launch the Optimization.

Step 7: View the Iteration Histor y of an Optim ization Study 1. Click the Iteration History tab to display data in a tabluar view. The o ptimal design is highlighted green, the infeasible designs are shown with red text, and the violated constraints are indicated in bold text.

2. Click the Iteration Plot 2D tab to plot the iteration history of the study's objectives, constraints, and design variables. 3. Using the Channel selector, select Objective 1, Constraint 1, and Constraint 2.

Tip: In the initial design, the design was infeasible as indicated by the large circular m arker for the first iteration. A view of the constraint plots shows that the second constraint was violated in the initial design. Initially, the optimizer added some weight in order to satisfy the design constraints. Notice that both constraints are near their bounds in the optimal design.


HyperWorks 14.0

Intro to RADIOSS v14 Exercises HM 2017-03-17

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