Lecture 05 14.5 Release
ANSYS Aqwa/Mechanical Aqwa/Mechanical Load mapping
A. ANSYS Offshore
Geometry modelling
AQWA
CFX/Fluent
HYDRO-STRUCTURAL DESIGN
Mechanical
...ANSYS Offshore Products •
Design Integration
Structural
Geometry
Motions/ Moorings
CFD
B. Load Mapping Process Geometry Modeler
3D Hydrodynamic Panel Model
Global Structural FE Model (Coarse Mesh for Yielding and Buckling Check)
Hydrodynamic Analysis Program
Motion and Load Response RAOs
Load Cases with Various Combinations of Hydrostatic Pressures and Hydrodynamic Pressures/Accelerations
Load Transfer and Balancing Program
Global FE Analysis Input with Coarse Mesh and Locally Refined Mesh for Each Load Case
FEA Solver
Structural Responses (Stress, Strain and Displacement)
Yielding, Buckling and Fatigue Code Checks
End
...Load Mapping Process Geometry Modeler
3D Hydrodynamic Panel Model
Global Structural FE Model (Coarse Mesh for Yielding and Buckling Check)
...Load Mapping Process 3D Hydrodynamic Panel Model
Hydrodynamic Analysis Program
Motion and Load Response RAOs
Load Cases with Various Combinations of Hydrostatic Pressures and Hydrodynamic Pressures/Accelerations
...Load Mapping Process
AQWA WAVE •
Calculation and transfer of loads to Mechanical
Load Cases with Various Combinations of Hydrostatic Pressures and Hydrodynamic Pressures/Accelerations
AQWA-LINE
AQWA
ANSYS
Model
WAVE
Model
Motions & Pressures
Load Transfer and Balancing Program A.K.A. AQWA WAVE
C. Load Transfer Requirements
Hydrodynamic database of pressures due to: •
Hydrostatics
•
Incident wave
•
Diffracted wave
•
Radiation effects
Structural mesh •
Define hull components
Steering information
...Load Transfer Requirements Pressure Mapping •
Free floating body, therefore no explicit boundary conditions
•
Wave pressure should be balanced by inertial loading
•
•
•
AQWA-WAVE computed inertial load based upon AQWA model mass and inertia matrix Inertial load may not exactly balance pressures due to differences between structural and hydrodynamic models Mass inertia information may be checked from the structural model ***********
PRECISE MASS SUMMARY
***********
TOTAL MASS (X,Y,Z)= 0.30039E+08 0.30039E+08 0.30039E+08 MOMENTS AND PRODUCTS OF INERTIA TENSOR (I) ABOUT ORIGIN (GLOBAL CARTESIAN) 0.10717E+10-0.81854E+07-0.11227E+06 -0.81854E+08 0.24025E+10 -49530. -0.11227E+06 -49530. 0.14226E+10 CENTER OF MASS (X,Y,Z)= 0.91020
0.95273
26.619
MOMENTS AND PRODUCTS OF INERTIA TENSOR (I) ABOUT CENTER OF MASS (GLOBAL CARTESIAN) 0.45005E+10-0.80984E+07 0.24211E+07 -0.80984E+07 0.36903E+10 0.25410E+07 0.24211E+07 0.25410E+07 0.34224E+10 PRINCIPAL CENTROIDAL MOMENTS OF INERTIA= 0.45010E+10 0.36852E+10 0.34224E+10
...Load Transfer Requirements Panel pressures are extracted from database Nodal values are computed from weighted averaging of pressures of connected panels Finite element nodal pressures computed from weighted averaging of hydrodynamic nodal values
P1
P5 N1
P2
P6 N2
P3
P7
P4
N1
N3
N2
N4
...Load Transfer Requirements Hull definition •
Pressure mapping is for outer hull only, therefore we need to define this
We make use of named selections, or groups, to define the outer hull A dummy pressure load is applied to the outer hull for transfer to the mapping interface file
D. Structural Analysis Free floating body analysis AQWA WAVE
Global FE Analysis Input with Coarse Mesh and Locally Refined Mesh for Each Load Case
FEA Solver
Structural Responses (Stress, Strain and Displacement)
Yielding, Buckling and Fatigue Code Checks
End •
ANSYS offers two facilities to help with free floating model analysis –
Inertial relief; Computes accelerations based upon structural model
–
Weak springs; Automatically removes free body singularities
...Structural Analysis
Structural Mesh
...Structural Analysis
Stress Results
...Load Transfer Requirements ANSYS DM Geometry
Hydrodynamic Mesh
Structural Mesh
ANSTOASAS
AQWAWB Solve Structural Data
Hyd Database
Control Data
AQWA WAVE
Pressure and Acceleration Data
/TITLE, CASE 1001 'H = 2.0 T = 62.8 D = 0.0 P = 0.0' ! COMPONENT ANSY SFEDELE,ALL,ALL,PRES FDELE,ALL LSCLEAR,INER SFE, 2409, 2,PRES,0, 0.0000E+00, -1.9740E+02, -1.9576E+02, SFE, 2411, 2,PRES,0, 0.0000E+00, 0.0000E+00, -2.0081E+02, SFE, 2412, 2,PRES,0, -1.9558E+02, -1.9503E+02, 0.0000E+00, SFE, 2416, 2,PRES,0, 0.0000E+00, 0.0000E+00, -2.8120E+01, SFE, 41361, 2,PRES,0, -3.9148E+02, -3.8728E+02, -3.8728E+02, SFE, 41362, 2,PRES,0, -3.9092E+02, -3.8734E+02, -3.8728E+02, SFE, 41363, 2,PRES,0, -3.9490E+02, -3.9511E+02, -3.8924E+02, SFE, 41364, 2,PRES,0, -3.9014E+02, -3.8543E+02, -3.8734E+02, ACEL, 1.9891E-07, 4.2397E-07, -1.0044E-02 CGLOC, 0.0000E+00, 0.0000E+00, 2.5400E+01 DCGOMG, 3.0279E-08, -2.4966E-08, 3.1457E-10
0.0000E+00 -1.9777E+02 0.0000E+00 0.0000E+00 -3.9161E+02 -3.9148E+02 -3.9014E+02 -3.9092E+02
...Structural Analysis
AQWA-Intro_14.5_WS05.1_Load_Mapping.pptx
