4.3.1 Overview of 1D connections Estimated time to complete this course: 35–57 minutes
This course discusses 1D connection elements which are used to !oin multiple meshes. "fter #ou complete this course #ou should $now the t#pes of 1D connections that are availa%le and %e a%le to use 1D connection elements in #our models.
&etup information Part folder: parts'simulat parts'simulation ion NX role: "dvanced with full menus
1
[Date]
System preparation
4.3.( 1D connections )se 1D connections to:
*onnect component +E,s within an assem%l# +E,.
*onnect multiple sheet and solid %odies within a +E,.
,odel pins and %olts.
Distri%ute mass loads or constraints.
Define connection points for fle-i%le %od# anal#sis.
2
[Date]
4.3.3 eometr#/%ased 1D connections The 1D Connection
command supports %oth 0eometr#/%ased and +E/%ased connections. eometr#/%as eometr#/%ased ed connection t#pes
include:
Point to Point
Point to Edge
Point to Face
3
[Date]
Edge to Edge
Edge to Face
4.3.4 +E/%ased 1D connections The 1D Connection command lets #ou create +E/%ased 1D connections. This t#pe of connection is useful when #ou reuire precise control of node location or when the underl#in0 0eometr# is not availa%le. 2owever +E/%ased connections ma# not %e updated correctl# if the 0eometr# or mesh is modified. +E/%ased connection t#pes include:
Node to Node
4
[Date]
Element Edge to Element Face
Node-to-node connection distributing a lumped mass on an imported mesh
4.3.5 *onnectin0 ed0es and faces To connect a set of ed0es to a set of faces use the Edge to Face 0eometr#/%ased or Element Edge to Element Face +E/%ased connection t#pe. )se this feature to connect meshes in a T/!unction confi0uration for e-ample to attach fins or stiffeners to surfaces. f #ou are usin0 the 6astran solver the software pro!ects 8E( elements from the selected ed0e to the selected face and then uses 8E3 spider elements to tie the pro!ected nodes to nodes on the face mesh.
5
[Date]
4.3.9 *onnectin0 points and nodes ou use point/to/point 0eometr# %ased and node/to/node +E/%ased connectors to connect nodes or points on one %od# or component +E, to nodes or points o n another %od# or component +E,. T#pical uses for these connection t#pes include:
,odelin0 structures such as pins %olts or struts.
*reatin0 spider elements for distri%utin0 masses or loads.
;oinin0 meshes when ed0e/to/ed0e or ed0e/to/face connections are not appropriate. +or e-ample #ou can use node/to/node connections to !oin imported meshes with no underl#in0 0eometr#.
6
[Date]
One-to-one, point-to-point beam element
4.3.7 Definin0 spider element connections " spider t#pe of connection is one in which #ou connect a sin0le node the core node to multiple nodes le0 nodes with a ri0id or constraint element. The t#pes of elements #ou can use to create a spider connection depends upon #our specified solver.
The first point #ou select %ecomes the core node.
7
[Date]
The selected ed0e or face define the locations of the le0 nodes. " 0roup of smart selection methods is availa%le on the Selection Bar to help #ou select the le0 nodes.
"fter #ou create the spider connection #ou can ma$e specific de0rees of freedom active or inactive %# editin0 the element attri%utes.
4.3.=
6astran 8E( and 8E3 elements are freuentl# used as spider elements.
8
[Date]
RBE2 elements
The active de0rees of freedom of the sin0le core node independent enforce the active de0rees of freedom of the le0 nodes dependent.. Therefore the active de0rees of freedom of all nodes included in an 8E( element are considered ri0idl# connected. dependent
(1) independent node (2) dependent nodes
RBE3 elements
The wei0hted avera0e of the active de0rees of freedom of the le0 nodes independent enforces the active de0rees of freedom of the sin0le core node dependent. This wei0htin0 is set to 1 and cannot %e chan0ed in 6>? all nodes contri%ute to the motion euall#. )nli$e the 8E( the 8E3 element is fle-i%le not infinitel# ri0id due to the allowa%le freedom of the le0 nodes. *ommon uses for
9
[Date]
this element t#pe include addin0 and distri%utin0 mass without addin0 stiffness and distri%utin0 distri%utin0 a load from multiple points to a sin0le point.
(1) dependent node (2) independent nodes
4.3.@ Aideo: creatin0 a 1D connection
10
[Date]
4.3.1B "ctivit#: *onnect nodes with spider elements
11
[Date]
Estimated time to complete: 15–(5 minutes ou will learn how to:
"utomaticall# create a spider element. ,anuall# create a spider element. ,anuall# update a spider element. )pdate a spider element if the underl#in0 0eometr# chan0es.
Caunch the Connect nodes with spider elements activit#.
4.3.1B.1 Open the part file Open
12
[Date]
+iles of t#pe
Part Files (*.prt)
spider.prt
+ile name
O K
Start
→
Advanced Simlation
4.3.1B.( eset the dialo0 %o- memor# The options #ou select in 6> dialo0 %o-es are preserved for the ne-t time #ou open the same dialo0 %o- within an 6> session. estore the default settin0s to ensure that the dialo0 %o-es are in the e-pected initial state for each step of the activit#.
13
[Date]
Preferences
!ser "nterface
→
#eset Dialog $emory
O K
4.3.1B.3 *reate the +E, and &imulation files
14
[Date]
Simlation Navigator
spider%prt
Ne& FE$ and Simlation
Create "deali'ed Part
&olver
NX NASTRAN
"nal#sis T#pe
Structural
OK
Ne& FE$ and Simlation dialo0 %o-
OK
4.3.1B.4 *reate a (D seed mesh *reate a (D seed mesh that will force the 3D mesh to follow a paver mesh around the holes in the part.
15
[Date]
(D $es) Advanced Simlation tool%ar $es) Drop*do&n list
T#pe
CQUAD4
,eshin0 ,ethod Element &ie
16
Paver
9
[Date]
6ote )se the default units unless otherwise specified.
$es) Settings
E+port $es) to Solver
O K
4.3.1B.5 *reate a 3D mesh
17
[Date]
,D -etra)edral $es) Advanced Simlation tool%ar $es) Drop*do&n list
the part
T#pe
CTETRA(!)
Element &ie
9
Destination Collector
Ne& Collector
Create P)ysical
C)oose material
,aterial
18
Alu"i#u"$%!4
[Date]
O K
$aterial .ist dialog /o+
O K
PSO."D dialog /o+
O K
$es) Collector dialog /o+
Atomatic Creation
,esh *ollector
S&lid()
O K
19
,D -etra)edral $es) dialog /o+
[Date]
4.3.1B.9 *reate spider elements *reate spider elements in each of the holes in the model to provide a place for load application.
1D Connection Advanced Simlation tool%ar Connections Drop*do&n list
-ype
P&i#t t& Ed'e
20
[Date]
Sorce
Select Point
&elect the arc center as the source.
-arget
Select Edge
21
[Date]
Tpe
RE%
$id*Node Option
Connect $id*Nodes
Apply
1D Connection dialo0 %o-
epeat these steps for the ne-t two holes movin0 cloc$wise from the upper/left e-cept turn on the Connect $id*Nodes option.
22
[Date]
6ote The upper left hand hole has fewer le0s to its spider element since it is not usin0 the mid/nodes.
Cance l
1D Connection dialo0 %o-
4.3.1B.7 *reate the last spider element rior to creatin0 the last spider element #ou need to create a node at the center of the last hole.
Node Create Node Operations tool%ar 6ote ou ma# need to displa# the Node Operations tool%ar.
23
[Date]
.ocation
Specify Point "rcFEllipseF&phere *enter
O K
1D Connection Advanced Simlation tool%ar Connections Drop*do&n list
-ype
24
[Date]
N&de t& N&de
Sorce
&elect the node that #ou created in the previous step.
Select Node
-arget
&tart %# selectin0 a node on the hole ed0e.
Select Node
*ontinue selectin0 ever# other node alon0 the
ed0e of the hole.
Tpe
RE%
O
25
[Date]
K
n the ne-t step #ou will modif# this element.
4.3.1B.= ,odif# element connectivit# ,odif# the connectivit# for the last spider element created to increase the num%er of le0s.
Element $odify Connectivity Element Operations tool%ar 6ote ou ma# need to displa# the Element Operations tool%ar.
26
[Date]
Elements to $odify
Si#'le Ele"e#t
&elect the spider element.
27
[Date]
Tpe
&di+ ,e' N&des
&elect the three nodes shown to add three le0s to the spider
element.
O K
ou can continue addin0 le0s to the spider element or removin0 others %# holdin0 down shift to deselect. The final steps of this activit# will add a constraint and loads.
28
[Date]
4.3.1B.@ ,a$e the &imulation file the wor$ part The +E, is currentl# the wor$ part while the &imulation file is the displa#ed part. ,a$e the &imulation file the wor$ part so that #ou can appl# %oundar# conditions.
Simlation Navigator
Simlation File 0ie&
spidersim1
$a2e 3or2 Part
4.3.1B.1B *onstrain the 0roove *onstrain the 0roove on the underside of the part.
29
[Date]
Fi+ed -ranslation Constraint Advanced Simlation tool%ar
Constraint -ype list
T#pe +ilter Tip
P&l'&# Face
The -ype Filter
is located on the &election %ar in the tool%ar area.
O K
4.3.1B.11 *reate a 0roup *reate a 0roup for load application.
30
[Date]
Simlation Navigator
4rops
Ne& 4rop
T#pe +ilter
N&de
&elect the center node of each spider element.
Name
Spider Nodes
OK
4.3.1B.1( "ppl# loads )se the newl# created 0roup to appl# loads to the spider elements.
31
[Date]
Force tool%ar
.oad -ype list
$odel O/5ects
4rop #eference
Na"e Spider N&des
+orce
1BB
Specify 0ector
–>* "-is
Distri/tion
$et)od
Total per O%!ect
32
[Date]
O K
6ote "t this point #ou can chec$ the model solve it and displa# the results prior to proceedin0. The followin0 steps will cause the loss of the load due to modifications to the spider elements.
4.3.1B.13 Displa# the idealied part Displa# the idealied part so #ou can modif# 0eometr#.
33
[Date]
Simlation Navigator
Simlation File 0ie&
spiderfem1i
$a2e Displayed Part
OK
"deali'ed Part 3arning messa0e %o-
4.3.1B.14 romote the part Promote Advanced Simlation tool%ar
the part %od#
OK
4.3.1B.15 ,odif# the hole diameter ,odif# the diameter of one of the holes and all four will %e updated to the new sie.
34
[Date]
in the tool%ar area
Sync)ronos $odeling
#esi'e Face Sync)ronos $odeling tool%ar $odify Face Drop*do&n list
Si'e
35
[Date]
Dia"eter
!
O K
6ote "ll four holes update to the same diameter.
36
[Date]
4.3.1B.19 Displa# the +E, file ,a$e the +E, file %oth the displa#ed part and wor$ part.
Simlation Navigator
Simlation File 0ie&
spiderfem1
$a2e Displayed Part the "nformation window if necessar#
37
[Date]
6ote The mesh is not updated %ut if #ou hover the cursor over the %od# #ou can see the outline of the modified hole 0eometr#.
4.3.1B.17 )pdate the mesh 6> updates the spider elements when #ou update the mesh.
!pdate Finite Element $odel Advanced Simlation tool%ar
6es
$es) !pdate messa0e %o-
&croll throu0h the "nformation window. 6otice that the manuall# created spider element will deleted from the model when the mesh is updated.
%e
the "nformation window
The 0eometr#/%ased spider elements are updated accordin0 to their recipes. The manuall# created spider element is no lon0er visi%le. The mesh that contains the manuall# created spider element is still present in the Simlation Navigator under 1D
38
[Date]
Collectors #BE( Collector789 %ut is no lon0er listed under Connection Collectors element #ou must recreate it usin0 either the 0eometr#/%ased or manual method. →
File
→
Close
→
→
Connections. f #ou want this spider
All Parts
ou completed the activit#.
4.3.11 ,odelin0 %olted connections The Bolt Connection command automaticall# creates an element that represents the shan$ of the %olt and a pair of spider elements that connect the ends of the element to the surroundin0 mesh. )se the Bolt Connection
command to model the followin0 t#pes
of %olted connections with finite elements:
" %olt that is held in place with a nut.
" %olt in a tapped threaded hole.
" %olt/t#pe connection that is represented %# onl# a spider element at the !unction plane %etween two matin0 %odies.
The wa# that the software models the %olt depends on #our specified solver environment. T#picall# 1D elements are used to model the %oltGs shan$. To connect those 1D elements to the nodes in the surroundin0 mesh the software creates a spider/t#pe connection.
39
[Date]
4.3.1( "ctivit#: ,odel %olted connections Estimated time to complete: 15–(5 minutes ou will learn how to:
40
[Date]
)se a *8E", element to represent a %olt and use 8E3 spider elements to connect the ends of the %olt to the surroundin0 mesh. "ppl# a preload force to the %olt. *reate a second su%case so that the com%ined effect of %olt preload and service loads can %e compared to %olt preload alone. E-amine the stresses actin0 on the cross section of the %olt.
Caunch the Model olted connections activit#.
.
4.3.1(.1 Open the part ou will use a trailer hitch part for this activit#.
41
[Date]
Open
+iles of t#pe
Part Files (*.prt)
trailer$-itc-.prt
+ile name
O K
The trailer hitch consists of a %all stud %olted to a draw %ar. "ll parts are steel. The thread on the %all stud is 1 / = )6* havin0 a tensile stress area of B.9B9 in (.
Start
Advanced Simlation
→
4.3.1(.( eset the dialo0 %o- memor#
42
[Date]
The options #ou select in 6> dialo0 %o-es are preserved for the ne-t time #ou open the same dialo0 %o- within an 6> session. estore the default settin0s to ensure that the dialo0 %o-es are in the e-pected initial state for each step of the activit#.
Preferences
!ser "nterface
→
#eset Dialog $emory
O K
43
[Date]
4.3.1(.3 *reate the +E, and &imulation files Simlation Navigator
trailer)itc)%prt
Ne& FE$ and Simlation
Create "deali'ed Part
&olver
NX NASTRAN
"nal#sis T#pe
Structural
OK
44
%oth dialo0 %o-es
[Date]
4.3.1(.4 Displa# the +E, file *urrentl# the +E, file is the wor$ part and the &imulation file is the displa#ed part.
Simlation Navigator
Simlation File 0ie&
trailer)itc)fem1
$a2e Displayed Part
45
[Date]
4.3.1(.5 Turn off displa# of the %all stud and nut Simlation Navigator
Polygon 4eometry e-pand
Polygon Body 719 deselect
Polygon Body 7,9 deselect 6ote f #our pol#0on %odies are num%ered differentl# deselect the %all stud and nut to produce the result shown %elow.
46
[Date]
4.3.1(.9 *reate a 3D mesh collector $es) Collector Advanced Simlation tool%ar
Element +amil#
D
*ollector T#pe
S&lid
Create P)ysical Solid Property
47
[Date]
C)oose material $aterial
,aterials
Steel
OK
all dialo0 %o-es
4.3.1(.7 ,esh the draw %ar ,D -etra)edral $es) Advanced Simlation tool%ar $es) Drop*do&n list
the part
T#pe
CTETRA(!)
Element &ie
48
B.(5
[Date]
Destination Collector
Atomatic Creation
,esh *ollector
S&lid()
O K
Save
4.3.1(.= Define ph#sical properties for the threaded portion of the %all stud )se a circular cross section to represent the shape of the threaded portion of the %all stud. 8ecause the tensile stress area is B.9B9 in( enter B.44 in for the radius.
$es) Collector Advanced Simlation tool%ar
Element +amil#
49
D
[Date]
*ollector T#pe
ea" C&llect&r
Create P)ysical Beam Property
S)o& Section $anager Fore Section Create Section
T#pe
R/D
D,1
B.44
O K
Beam Section dialog /o+
Clos e
Beam Section $anager dialog /o+
,aterial
50
Steel
[Date]
O K
/ot) dialog /o+es
4.3.1(.@ ,odel the threaded portion of the %all stud ,odel the threaded portion of the %all stud with a *8E", element. )se 8E3 spider elements to connect the ends of the *8E", element to the surroundin0 tetrahedral mesh.
51
[Date]
Bolt Connection Advanced Simlation tool%ar Connection Drop*do&n list
T#pe
< 0it- Nut
Nt
Select Edge
S)an2 Element
T#pe
52
CEA
[Date]
Atomatic Creation
,esh *ollector
ea" C&llect&r()
Spider Connection
T#pe
RE
O K
4.3.1(.1B elease DO+ from 8E3
53
[Date]
To assure deformations of the tetrahedral mesh do not cause the %olt to twist release the DO+ that corresponds to rotation a%out the %olt a-is from one of the 8E3 elements.
Simlation Navigator
1D Collectors e-pand
#BE, Collector719 e-pand
8oth 8E3 elements are contained in the /oltrecipe1spider mesh. f #ou release the DO+ that corresponds to rotation a%out the %olt a-is for %oth 8E3 elements #ou will introduce a sin0ularit#. To avoid doin0 so e-tract one of the 8E3 elements from the /oltrecipe1spider mesh. Then release the DO+ of onl# the e-tracted 8E3 element.
Edit
Element
→
E+tract
→
O K
n the Simlation Navigator two
54
meshes are now listed under #BE, Collector719.
[Date]
1de+tractedmes)719
Edit $es) Associated Data
Element Properties
D/F1
/++
O K
4.3.1(.11 Displa# the &imulation file Simlation Navigator
Simlation File 0ie&
trailer)itc)sim1
55
[Date]
$a2e Displayed Part
4.3.1(.1( "ppl# pinned constraints " clevis pin is used to assem%le the trailer hitch to a receptacle mounted on the vehicle. "ppl# pinned constraints to the two c#lindrical surfaces in the draw %ar to model the %ehavior of the clevis pin.
Pinned Constraint Advanced Simlation tool%ar
Constraint -ype list
O K
56
[Date]
4.3.1(.13 "ppl# a user defined constraint otation of the trailer hitch is prevented %# the end of the draw %ar contactin0 the mountin0 receptacle. ,odel this %ehavior %# appl#in0 a user defined constraint to the end of the draw %ar.
!ser Defined Constraint Advanced Simlation tool%ar
Constraint -ype list
T#pe +ilter
57
P&l'&# Ed'e
[Date]
Tip
The -ype Filter
is located on the &election %ar in the tool%ar area.
Degrees of Freedom
DO+3
Fi2ed
O K
58
[Date]
4.3.1(.14 "ppl# %olt preload "ppl# a 39BBB l%f preload to the *8E", element representin0 the %olted portion of the %all stud.
59
[Date]
Bolt Pre*.oad Advanced Simlation tool%ar
.oad -ype list
T#pe +ilter Tip
Ele"e#t
The -ype Filter
is located on the &election %ar in
the tool%ar area.
+orce
39BBB l%f
O K
Save
4.3.1(.15 &olve the model
60
[Date]
Simlation Navigator
Soltion 1
Solve
OK
Solve dialo0 %o-
The Analysis :o/ $onitor dialo0 %o- appears.
Cance l
Analysis :o/ $onitor dialo0 %o-
Clos e
61
Soltion $onitor dialo0 %o-
[Date]
4.3.1(.19 Aiew the anal#sis results Simlation Navigator
#eslts
Post*Processing Navigator
Stress * Element*Nodal e-pand
0on*$ises
The results are displa#ed in the 0raphics window.
The deformations are 0reatl# e-a00erated. Turn off the deformed model displa#.
Edit Post 0ie& Post Processing tool%ar Deformation
62
[Date]
Apply
*reate a cuttin0 plane displa# to view how the stress varies throu0h the cross section around the hole.
Displa &#
Cutti#' Pla#e
Options
Display on
3
Cut Pla#e
Clip Side
Ne'ative
6;
<
63
[Date]
OK
%oth dialo0 %o-es
#etrn to $odel .ayot $anager tool%ar Tip ou ma# need to turn on the .ayot $anager tool%ar.
64
[Date]
4.3.1(.17 *reate new su%case Simlation Navigator
Soltion 1
Ne& S/case
OK
65
[Date]
4.3.1(.1= "ppl# service loads n the newl# created su%case appl# the service loads.
Force Advanced Simlation tool%ar
.oad -ype list
T#pe
C&"p&#e#ts
T#pe +ilter &election %ar
N&de
Tip )se =ic2Pic2 to help #ou select the node at the end of the %olt rather than nodes from the tetrahedral mesh.
66
[Date]
+#
/4BBB l%f
+
/9BB l%f
O K
$oment Advanced Simlation tool%ar
.oad -ype list
67
[Date]
T#pe
C&"p&#e#ts
T#pe +ilter &election %ar
N&de
,-
74BB l%f/in
O K
68
[Date]
4.3.1(.1@ "dd %olt preload to the new su%case Simlation Navigator
.oad Container e-pand
Dra0 Bolt Pre*.oad719 to .oads under S/case > Static .oads ( .
69
[Date]
ou can e-pand the .oads node under the S/case > Static .oads ( node to see that Bolt Pre*load719 is now part of the loadin0.
Save
4.3.1(.(B &olve the model for the new su%case Simlation Navigator
Soltion 1
70
[Date]
Solve
OK
Solve dialo0 %o-
The Analysis :o/ $onitor dialo0 %o- appears.
Cance l
Analysis :o/ $onitor dialo0 %o-
Close
4.3.1(.(1 Aiew the anal#sis results Simlation Navigator
71
[Date]
#eslts
Post*Processing Navigator
S/case ? Static .oads ( e-pand
Stress * Element*Nodal e-pand
0on*$ises
The results are displa#ed in the 0raphics window.
*reate a cuttin0 plane displa# to view how the stress varies throu0h the cross section around the hole.
Edit Post 0ie& Post Processing tool%ar Deformation
Apply
72
[Date]
Displa &#
Cutti#' Pla#e
Options
Display on
3
Cut Pla#e
Clip Side
Ne'ative
6;
<
OK
73
%oth dialo0 %o-es
[Date]
#etrn to $odel .ayot $anager tool%ar
74
[Date]
4.3.1(.(( *alculate stresses in the threaded portion of the %all stud To o%tain the stresses actin0 on the cross section of the threaded portion of the %all stud #ou must first reuest force output from the solve.
Simlation Navigator
Soltion 1
Solve
Edit Soltion Attri/tes
Case C&#tr&l
Edit Otpt #e@ests
F&rce
75
[Date]
Ena/le FO#CE #e@est
OK
all dialo0 %o-es
The Analysis :o/ $onitor dialo0 %o- appears.
Cance l
Analysis :o/ $onitor dialo0 %o-
Clos e
76
Soltion $onitor dialo0 %o-
[Date]
4.3.1(.(3 Aiew the stresses in the threaded portion of the %all stud Simlation Navigator
#eslts
Post*Processing Navigator
S/case * Static .oads ( e-pand
Beam #esltants > Elemental and Beam #esltants > Element*Nodal are now included in the list of results. Stress * Element*Nodal e-pand
77
[Date]
0on*$ises
Cross > Section 0ie& Post Processing tool%ar
Previe&
The Cross*Section Previe& window opens automaticall#.
Apply
78
[Date]
The von ,ises stress actin0 on the cross section is displa#ed at the end of the %olt #ou selected. ou can also displa# the stress actin0 on the cross section at the other end of the %olt.
At E#d
A+t 445%
6ote n #our model the element num%er ma# %e different.
Apply
ou can also chan0e which stress component is displa#ed.
Display
79
[Date]
#eslt
Su6case 7 Static ,&ads %
Stress
%
OK
all dialo0 %o-es
The transverse shear stress actin0 on the cross section in the direction is displa#ed.
80
[Date]
#etrn to $odel .ayot $anager tool%ar
File
Close
→
All Parts
→
ou completed the activit#.
4.3.13 eview Huestion 1 es es %ut onl# if the spider element is +E/%ased es %ut onl# if the spider element is 0eometr#/%ased 6o ✓ Show
81
feedback
[Date]
