关于有限元分析教程

维分子

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[ 本帖最后由 维分子 于 2008-3-28 09:08 编辑 ]

维分子

有限元分析的主要步骤
: ?) n+ C5 a5 g" W前处理
建立分析对象的有限元模型
- H$ r( c6 q# B7 l' w4 i求解
对有限元模型的计算工况进行求解
后处理
9 w2 C1 N# L) W) ~) n( Z5 w& C2 f6 o观察分析结果，评估设计是否符合要求

维分子

Cosmos/Works有限元分析的步骤
建立几何模型
0 r2 v( k7 S, p8 r# b$ W定义材料属性
% M! o1 P- l" L/ ^定义边界条件(约束和载荷)
划分网格
求解
6 ?) ?/ ]+ j3 b# V查看和评估结果

维分子

企业需求与有限元分析
% H' H+ |  {5 F, U4 j4 ^更少的样机：省钱
更短的周期：省时
更好的质量：品质

维分子

线性静力分析：定义专题
Displacement in the radial direction:
Select “Axis1” and then define displacement plot in X-direction (radial to the axis). Select deformation scale=1
Right-click on the displacement plot icon “plot2” and then select”List selected”
Average displacement of “pole piece lower” = -0.0019504” (decrease in radius)
Average displacement of “pole piece upper” = 0.007896 “ (increase in radius)
Sum of these 2 displacement = 0.009846” ~Initial interfernce of 0.01”
6 J2 ?+ `- x$ w( |Hoop Stress (tangential):
. }8 ~5 I, v. bSelect “Axis1” and then define stress plot in Y-direction (radial to the axis). Select deformation scale=1
, s* [7 _& G4 MRight-click on the stress plot icon “plot2” and then select”List selected”
Negative stress on “pole piece lower” (compression)
+ d- \# j  A% g) R$ r* P, y* HPositive stress on “pole piece upper” (tension)
! {% s! _7 g: s- ?线性静力分析：定义材料属性
Simulate parts which are separated by large gaps
. }. ]$ o, p% p$ ]4 `+ _6 N( rFirst run the model with small displacement option and look at the results
9 v$ j3 R6 y/ x; M/ O If you see that there is a change in the orientation of the contact surfaces during loading or if the results doesn’t look realistic, use large deflection option

& z9 ~! N# U2 K, `3 }  L线性静力分析：网格划分
& c+ z8 G4 y+ X. H3 dOpen “RectangleGap.sldasm”
Define a static study “smallcontact”
Apply material “Alloy steel” to both parts
Apply a pressure of 725 psi on the top face
Select the two front faces and then apply restraint. Select Flat face option and then select “Normal to face”
4 [6 Y5 ~: B% P- pFix the left semi-circular face
5 ]% r. }+ p5 XHide the loads/bc symbols
) P& K" `: u: R: O, a, [Define “Surface” contact between the top face of the bottom leg and the perpendicular face
" b+ k4 G7 A) Q9 jCreate mesh and run
: z) X- e# s8 z' b9 K% iDefine a stress plot with scale factor = 1. Look at the contact surface.
线性静力分析：定义约束
Define a new static study “LargeDisp”
, z) d( @9 G# f8 RDrag’n drop the material and loads/bc folders from “small contact” study
Right-click on the study name and click on properties. Select “Large displacement contact” option.
8 R: s; O0 Y* w! V& |7 k7 B0 `5 j" ZRun the analysis
Define a stress plot with scale factor = 1. Look at the contact area.
4 o) a1 P  ~" W线性静力分析：定义载荷
! z" V4 v4 `: Y; QSimulate heat resistance between parts for thermal analysis
/ U/ b' u# {6 w3 o! y8 n' q Account for heat resistance of thin parts without actually modeling them!

线性静力分析：求解
Open “Thermal contact resistance_transistor.sldasm”
Explode the model and set preferred units to “SI” and temperature units to “Kelvin”
6 s5 j$ c0 O/ A) KDefine a thermal study “NoRes”
; S8 D8 Y3 n8 J1 dApply material “AISI 304” for “Voltage regulator” and “Copper” for Heat sink
Define “Surface” contact with No resistance between the contact faces
Apply convection to all the faces of the model except the contact faces
Film coefficient = 250 W/(m^2.K)
! h: [1 J, ~8 h5 D# [# |3 H4 iBulk temperature = 298 K
线性静力分析：观察结果
& M0 b; @! G2 O) }: cApply Heat power = 25 W for “Voltage regulator”
$ ?/ M+ H  l9 C9 XMesh with default settings and run the analysis
9 u* y+ j' w" e/ z9 fNotice the temperature distribution of the heat sink
: t5 o" I+ _% r7 m& lDistributed Resistance:
& F+ C5 m7 ?! Q, {1 x' k7 dDefine a new thermal study “DistRes”
% x3 A$ `2 y4 y! z2 B! Q1 A4 hDrag’n drop “Material” folder and Loads/Bc folder from NoRes study to DistRes study
% u: b3 ?3 ~- I$ LEdit contact pair definition and define distributed resistance = 0.005 K.m^2/W
" A: K/ G' Y# H" gTotal resistance = Distributed resistance X Contact area                           = 0.005 X 0.0003392 = 14.7 K/W
( t: |8 s* ^) R6 x5 g( `Run the study “DistRes”
: d% u9 [+ R, ^1 a( X% }- MNotice the temperature distribution of the heat sink
' z8 \/ u8 l6 [# hThermal Contact Example (Cont’d)
% R8 y" ?- n5 c5 U! NProbe the temperature value
Define a thermal plot with mesh
! @) y: o3 M/ z- B+ aRight-click the plot icon and select Probe
Pick all the nodes on the edge of both the parts
Click on the Plot icon to view the temperature variation from the top face of the voltage regulator to the bottom of the heat sink

Thermal Contact Example (Cont’d)
Total Resistance:
Define a new thermal study “TotalRes”
4 Q  |* U$ ?! {3 A* y5 \Drag’n drop “Material” folder and Loads/Bc folder from NoRes study to TotalRes study
Edit contact pair definition and define Total resistance = 25 K/W
Run the study “TotalRes”
Notice the temperature distribution of the heat sink
; B2 n5 d5 I. ]0 v: [2 Q
Load Simulation: Remote Loads
Remote Loads
5 @8 ?: Q% g+ n4 W3 ^  QDirect Transfer
  J- \6 _) ^$ u. B/ iFlexible surface
Applied as equivalent force & moment
Rigid Beam
+ i$ l9 U7 ^, ]; c% [. cRigid surface
Remote Restraint
; ]* u) M& Z, WRigid connection
Model effect of a rigid virtual part between two faces
! l1 n  H- K5 Q- Z+ a  M' }
2 S( b; o5 p" l" }
$ q/ R/ X9 K! X( X0 ^Remote Load Example
% R4 T, a5 \- I; T0 U9 x+ m" jOpen “RemoteLoadExample.sldasm”
7 N+ u( ?% |( a" f4 I  P" g; FDefine a static study “Remote”
' Z" e9 Q/ ~) O) J1 dApply material “Alloy steel”
Fix the flat face
' m4 p; T, ^$ l+ U4 C7 p, p, ]Select “Coordinate system1” and the end face of the cantilever. Define remote load of 10N in the X direction.
& v7 Z: w3 W0 J2 O; c( c% uCreate mesh and run.
Double-click on “Plot1” under the stress folder
Animate the results
Compare the plot results of “Remote” study with “Axial Tension” study

  f, p% L/ j$ E0 r: G+ a: @Motion Load Transfer Using Remote Loads
+ E+ l* l6 `& G$ t* `+ V, x0 sGo to SW Add-in and click “COSMOS/Motion”
Open “LoadTransferModel_With_Result.sldasm”
+ s2 Y- B6 k; F( h) @- ]3 IPlay the animation and save the load file for frame # 300
) f5 }6 i2 u/ m  x- T' G$ Y  ?Delete the motion results
* A, o( V4 z( e' \& l2 ?Go to CW menu, Import Motion Load and open this load file from “MotionLoadTransfer” directory
Select all the loads related to crank-1 and then click OK.
: i& |9 K0 w' ~Open the part “crank”
You’ll see that there is a new study “Frame-300” with motion loads transferred as remote loads
( g  }* M! v. K) kApply material “Plain carbon steel”
Go to study properties and select “FFEPlus” solver and “Inertia relief option”
Run the analysis
: v& l7 _* _8 J2 ?/ PPostprocessing: Results in local CS
/ I3 f3 S& T3 V7 b# f* L! \Plotting
Listings
Reaction forces
Postprocessing: Exploded views
; i/ k3 X2 A$ w( BPlot results on SolidWorks exploded views
! v3 c: y' |+ C
Postprocessing: New tools
Improved probing with graphing option
" b7 D5 Y$ E% ^) p8 u  ]# w5 JList results by Entity
2 \+ I3 ^; l; D* qWeb Reports
0 L0 p2 D' a, S5 Q( L" WInclusion of report templates in the feature tree
9 S6 J( q0 O6 y+ n  l5 a, |Saving of report setting
Automatic creation of all plots
# g( S2 g+ y; r1 {Report Example
) b& v& s" S# Y9 n! F# t/ }0 o- hOpen “ReportExample.sldasm”
New option save JPEG files (Right-click on the Study name)
; q) ^8 {- c/ w0 M' Y# KRight-click on Report and click define
  a3 j4 q" }& _6 E, IPoint to the logo file “ReportLogo.bmp”
5 p% B: M4 B% ]0 B; QPoint to the right stress AVI and VRML files
; b3 D7 p- U: k2 X& y3 u+ ISelect option “Automatically update all plots in JPEG files”. Click OK.
You can also get a print version
$ n/ v# R# L# w- G6 hMaterial
Supports orthotropic material properties for solids and shells
Option to use different Material library files
: t  m, ?7 [# z( N1 D( X" ENew redesigned material browser utility
2 V1 A" @4 G- W5 L3 g7 x
Licensing
4 h' }, C0 o/ CSingle license file for hardware lock & FlexLM security
6 l8 t3 _# `( F* j; GNew License Administrator to manage the license
Support USB port hardware lock
, B: q- g) s2 }Support redundant servers

+ m$ W/ j4 W% B* aOther customer enhancements
! K+ N  S' v! ]( kAutomatically run analysis after meshing
Edge pressure for shells
Apply uniform temperature to components
Automatic adjustments of Max & min in plots on update
FFEPlus solver for thermal analysis
Increase the limit on number of modes for frequency analysis from 20 to 100
Add symbol for gravity loads
Improve section clipping
Save plots in JPEG format
* p4 W1 v0 l9 s2 R; L" \- vImprove transient thermal animations
7 m" J6 x: k; l, @0 B) E% COption to switch between different languages
  Q/ B1 \: O. \& P- o4 ?$ g8 p9 ?Others…

Thank You!