ansys, inc. proprietary © 2004 ansys, inc. chapter 1 ansys release 9.0

ANSYS, Inc. Proprietary© 2004 ANSYS, Inc.

Chapter 1

ANSYS Release 9.0

Chapter 1

ANSYS Release 9.0

ANSYS, Inc. Proprietary

© 2004 ANSYS, Inc.

October 1, 2004Inventory #002156

1-29.0 New Features

Topics

i. Structural Enhancements Solid Shell Element Rezoning – 2D Mesh Independent Spotwelds Pre-Integrated Shell/Beams Sections Follower Forces Non-Linear Diagnostics and Contact Temperature Dependent Curve Fitting Frequency Dependent Harmonic Analysis Complex Eigen Solver (QR Damp)

ii. Miscellaneous Enhancements Local CYS for Function BC’s Static Cyclic Symmetry Component Based Acceleration CMS Superelements

iii. Thermal Radiation Enhancements


Solid Shell Element 190Solid Shell Element 190


© 2004 ANSYS, Inc.


1-49.0 New Features

Shell Theory, Solid Shell Assembly and numerical locking in low-order elements

• Nonlinear MPCs or transitional elements are required for connecting shell and solid elements.

• Treatment of variable thickness is unclear.

• Definition of contact interaction needs special attention.

• Difficulties in the specialization of general three-dimensional material laws to plane-stress state.

• Complicated update of rotations in geometrically nonlinear analyses

• The error in the kinematic approximation with linear 3D solid elements becomes apparent in bending dominant problems.

• This error is magnified as the thickness decreases, which beyond a certain ratio may make the FE model excessively stiff.

• Current element technologies, such as the enhanced strain (or extra shapes), are not sufficient to remedy this numerical locking in linear 3D solid elements.


© 2004 ANSYS, Inc.


1-59.0 New Features

SolidShell 190

• Involves only displacement nodal DOFs and features an eight-node brick connectivity. Thus the connection problem between solid and shell elements can be eliminated.

• Performs well in simulating shell structures with a wide range of thickness (from extremely thin to moderate thick).

• Is compatible with 3D constitutive models and automatically accounts for thickness change.

• Performs well for both flat-plate and curved shells.

3

3

3

2

3

13

2

3

2

2

2

12

1

3

1

2

1

11

,,

,,

,,

r

x

r

x

r

xR

r

x

r

x

r

xR

r

x

r

x

r

xR

X3

X2

X1

r1

r2

r3


© 2004 ANSYS, Inc.


1-69.0 New Features

Convergence relative to mesh refinement

0

0.2

0.4

0.6

0.8

1

1.2

1 6 11 16 21 26

Number of Elements Per Edge

No

rmal

ized

Max

. Def

lect

ion

Shell181 (enhanced strain)

Solid185 (enhanced strain)

SolidShell 190

Normalized shell thickness ( t / L) : 0.001, linear static analysis


© 2004 ANSYS, Inc.


1-79.0 New Features

Modal Analysis of a Hemi-sphere Shell

thickness = 0.001 mesh density = 15 x 15 (Thin Shell)Mode Shell181 Enh Solid185 Enh SolidShell 190

1 3.07759484 8.239738235 3.0717603832 21.24648643 103.9636569 21.228723943 53.86043052 350.1158379 53.829848284 99.48796565 758.7461212 99.481637175 158.4547881 1303.958847 158.47231616 232.5992189 1927.192569 232.66981987 325.8971451 2484.333703 326.0458065

thickness = 0.1 mesh density = 15 x 15 (Thick Shell)Mode Shell181 Enh Solid185 Enh SolidShell 190

1 268.3336331 233.1024418 233.08097732 1401.119808 978.7538942 980.01414573 2400.852477 1761.461958 1763.3263394 3284.527205 2224.35367 2225.6287235 3590.50519 2403.006279 2402.6392126 3670.531134 3157.10644 3155.3068547 4179.724049 3418.795507 3420.088344


© 2004 ANSYS, Inc.


1-89.0 New Features

Car roof assembly under pressure load

Max. Deflection:

SOLID186: 0.001521

SOLID190: 0.001575

SOLID185: 0.001290

Linear Static Analysis


© 2004 ANSYS, Inc.


1-99.0 New Features

Large Deformation Example

• Half-symmetry about the Y-Z plane is used to model a rigid target cylinder pushing upwards on a SOLSH190 tapered beam (cyan-colored elements) connected to SOLID185 columns (purple-colored elements).

• The SOLSH190 elements are stacked two through the thickness to allow 4 integration points in that direction.

• The SOLSH190 elements are joined to the SOLID185 elements by virtue of the same nodes used for each.

• The base of the column is fixed.

• SOLID185’s

• Base Fixed

• SOLSH190’s

Common Nodes

Rigid Target Cylinder at Symmetry

Plane


© 2004 ANSYS, Inc.


1-109.0 New Features

Large Deformation Results

• Equivalent stress and equivalent plastic strain plots are shown to the right (top and bottom plots, respectively).

• Contact recognizes the outer surface of the SOLSH190’s and the interface with the SOLID185 elements transfers the loads correctly.

Nice Transition Region …

No Contact Penetration …Plastic Strain

Stress


2D Rezoning2D Rezoning


© 2004 ANSYS, Inc.



Need for Rezoning

• Mesh distortion terminates analysis


© 2004 ANSYS, Inc.



Rezoning in ANSYS

• What is rezoning?– Remesh base on the deformed domain at a

selected substep– Map the solved variables and achieve equilibrium

based on the mapped variables– Resume the solution based on the new mesh

• Long term goal:– Fully automatic rezoning with different adaptive

criteria to overcome mesh distortion and reduce discretization error


© 2004 ANSYS, Inc.



Current status

• Manual rezoning for 2D • Plane 182, B-Bar formulation

with or without mixed u/P formulation

• All stress states, i.e. plane strain, plane stress, axisymmetric, generalized plane strain

• All hyperelastic materials (TB, Hyper…)

• Analysis type:– Static analysis with nlgeom,

on

– Loads and boundary conditions:• Displacements• Forces• Pressures• Nodal temperature, applied by

BF,TEMP…

– Remesh • Manual remeshing

– Select the elements to remesh – Generate a area– Create the new mesh by

ANSYS meshing commands

– Based on multi-frame restart files


© 2004 ANSYS, Inc.



Rezoning Example


© 2004 ANSYS, Inc.



Rezoning Procedure

• In the following steps, the solution from TIME=0.8 will be used as the starting point for manual rezoning. The rezoning will create a new mesh based on the deformed geometry at 80% of the load and map the results from the old mesh to the new one. The solution will then be restarted from this point.

• The solution will stop at about 90% of the total load. During the solution, there may be errors generated about element distortion, where ANSYS will then automatically bisect.

• In the General Postprocessor, note the excessive element distortion at the bottom of the model.


© 2004 ANSYS, Inc.



Specify the Start of Manual Rezoning

• Restart from the point of 80% of the load

– GUI: Main Menu > Solution > Manual Rezoning > Start

• In the GUI, select the second to the last result set, which corresponds to the loading of 81% (load step 1, substep 77).

• In the GUI, the deformed mesh at any selected point can be evaluated by selecting the “View Deformed Geometry” button.

– Command: REZONE,MANUAL,1,77REMESH,START

• The rezoning points are based on the multiframe restart files (RESCONTROL command), not on what results are saved in the .rst result file. In this example, approximately ten evenly-spaced restart points were requested prior to the initial solution.

• In the GUI, there is also an option to create a .rst result file based on the selected multiframe restart point (ANTYPE,,RESTART,,,RSTCREATE command).


© 2004 ANSYS, Inc.



Create Remesh Zone

• Select the elements for rezoning

– GUI: Main Menu > Solution > Manual Rezoning > Create Remesh Zone(s) > Select Rezone Elements

• A dialog box will appear describing what to do. Click on “OK” to continue

• Select all elements of Type ID #1 after prompted. In the widget, select “Elements” “By Attributes” based on “Elem type num” of “1”, and click on “OK”

– Command: ESEL,S,TYPE,,1

• Create rezone area

– GUI: Main Menu > Solution > Manual Rezoning > Create Remesh Zone(s) > Select Rezone Elements

• Accept defaults and click on “OK”

– Command: AREMESH

• A new area will be generated based on the deformed mesh at TIME=0.8, as shown on the right (outline in red).


© 2004 ANSYS, Inc.



Remesh New Area

• Remesh the newly-created area

– GUI: Main Menu > Solution > Manual Rezoning > Create Remesh Zone(s) > MeshTool

• Under “Size Controls > Global > Set,” verify that the element edge length is set to 0.2

• Click on the “Mesh” button and mesh area #2

– Command: ESIZE, 0.2 AMESH,2

• The remeshed area is shown on the right. Mesh controls can be specified to enable the user to obtain any type of desired mesh. In this example, only a global element size was specified (same global element size as original model), which may result in a few triangular elements generated.

• Although the user can create a new mesh, please note that general Preprocessing functions, such as creating new geometric entities, are not available during the manual rezoning phase, as these preprocessing functions do not pertain to rezoning.


© 2004 ANSYS, Inc.



Map Results from Old to New Mesh

• Regenerate loads, boundary conditions, and contact pairs on the new model

– GUI: Main Menu > Solution > Manual Rezoning > Create Remesh Zone(s) > Transfer Boundary Conditions

– Command: REMESH,FINISH

• Map results from the old to the new mesh

– GUI: Main Menu > Solution > Manual Rezoning > Create Remesh Zone(s) > Map Results

– Command: MAPSOLVE

• The first step outlined here remaps all boundary conditions (loads, displacement constraints, and contact pairs) from the old to new mesh.

• The second step then remaps the solution variables (displacements, stresses, strains) from the old to new mesh and ensures equilibrium is achieved.


© 2004 ANSYS, Inc.



Continue New Solution

• Continue solution of new mesh

– GUI: Main Menu > Finish

– GUI: Main Menu > Solution > Analysis Type > Restart

• Specify the last restart point, which should be load step “1” and substep “78”. Click on “OK”

– GUI: Main Menu > Solution > Solve > Current LS

– Command: FINISH/SOLUANTYPE,,RESTSOLVE

• This time, the solution should complete to the end since the rezoning process generated better-quality elements from the restart point.

• Review results in the General Postprocessor

– GUI: Main Menu > General Postproc > Read Results > Last Set

– GUI: Main Menu > General Postproc > Plot Results > Contour Plot > Element Solution

• Select “Element Solution > Stress > von Mises Stress” and click on “OK”

– Command: /POST1SET,LASTPLESOL,S,EQV


© 2004 ANSYS, Inc.



Animate Results

• Animate Results– GUI: Utility Menu > PlotCtrls >

Animate > Over Results …– Command: ANDATA

• The animation of the deformed mesh is shown on the right. Although results are written to different files for rezoning operations, this is transparent to the user.


Mesh Independent Spot Welds

Mesh Independent Spot Welds


© 2004 ANSYS, Inc.



Mesh Independent Spot Weld

• In automotive and/or aerospace industries, many applications require modeling of spot welds between two or more thin parts

• The strength and fatigue properties of thin sheet components are considerably influenced by spot welds

• The traditional model of spot welds:– Matching meshes of different parts at spot weld

connection points.– Effects of spot weld radius is not taken into account– underestimates the strength of the spot weld

connection


© 2004 ANSYS, Inc.



• Parts can be meshed independently• The spot weld can be located anywhere between multiple parts that

are to be connected in a finite element model regardless of the mesh. • A spot weld is defined by the surfaces to be connected and a spot

weld node near the surfaces. The spot weld node determines the location of spot weld

• The location of the spot weld can be independent of the location of the nodes on the surface to be welded.

• The approach takes into account of effects of spot weld radius. ANSYS will generate – RBE3 type MPC via a contact pair on each spot weld surface. The

radius defines the range of force distribution.– A beam element to link the two adjacent surfaces. The beam has

physical radius.• The spot weld can be either rigid or deformed

Mesh Independent Spot Weld


© 2004 ANSYS, Inc.



Create a New Spot Weld Set


© 2004 ANSYS, Inc.




• SWGEN, Ecomp, SWRD, NCM1, NCM2, SND1, SND2, SHRD, DIRX, DIRY, DIRZ, ITTY,I CTY

• ECOMP – Spot weld set name. It is the element component and it is used to identify set of spot weld for list, output, and adding more surfaces.

• NCM1/NCM2: – Spot weld surfaces• Pre-defined node components (for select)• Meshed areas (for pick)• SND1: – First spot weld node. It determines the location of spot

weld. It can be one of node on surface NCM1 or an independent node near the surface. ANSYS will determine the actual location by projecting it onto surface NCM1.

Spot weldsurface 1

Spot weld node 1After projection

Original position of spot weld node 1

Spot weldsurface 1

Spot weld node 1After projection

Original position of spot weld node 1

Projection onto surfaceProjection onto surface Projection direction specified by userProjection direction specified by user


© 2004 ANSYS, Inc.




• SWRD – Spot weld radius. Each spot weld has a circular projection onto the spot weld surface. By the definition of each contact pair, ANSYS will form RBE3 type constraint equations internally which distribute internal force of contact node (i.e. spot weld node) to the target nodes lying with in the region of spot weld radius.

CONTA175(spot weld node 1)

Spot weldsurface 1

TARGE170 elements

Spot weld radius

CONTA175

Nodes to be constrained


© 2004 ANSYS, Inc.




• Beam element – connects two spot weld surfaces.– Rigid Link is a default : MPC184 with KEYOPT(1)=1– Deformed Link : if current defined element type is BEAM188 with

proper Material ID and section ID (solid circle)

Spot weldsurface 1

Spot weld node 1

Spot weldsurface 2

Spot weld node 2 A beam elementMPC184/BEAM188

Example: MP,EX,3,200000000000. ! define spot weld material propertiesMP,NUXY,3,0.3SECTYPE,3,beam,csolid ! define a cylinder beamSECDATA,2.75e-002 ! beam circular radiusET,3,188 ! define a deformed spot weldTYPE,3MAT,3SECNUM,3*SET,NODE1,9000 ! define a spot weld node N,NODE1,0.1,0.5,10.2 ! define location of spot weldSWGEN,SWELD1,2.75e-2,2,3,NODE1 ! Spot sweld name=SWELD1, ! RADIUS=2.75e-2, !Spot weld surfaces=AREA 2 and 3.

Example: MP,EX,3,200000000000. ! define spot weld material propertiesMP,NUXY,3,0.3SECTYPE,3,beam,csolid ! define a cylinder beamSECDATA,2.75e-002 ! beam circular radiusET,3,188 ! define a deformed spot weldTYPE,3MAT,3SECNUM,3*SET,NODE1,9000 ! define a spot weld node N,NODE1,0.1,0.5,10.2 ! define location of spot weldSWGEN,SWELD1,2.75e-2,2,3,NODE1 ! Spot sweld name=SWELD1, ! RADIUS=2.75e-2, !Spot weld surfaces=AREA 2 and 3.


© 2004 ANSYS, Inc.



Add more surfaces


© 2004 ANSYS, Inc.



Add more surfaces

SWADD, Ecomp, SHRD, NCM1, NCM2, NCM3, NCM4, NCM5, NCM6, NCM7, NCM8, NCM9Ecomp - The name of an existing spot weld set which composes contact, target and beam elements for the spot weld definition.SHRD - Search radius. It defaults to 4 times of spot weld radius SWRDNCM1-NCM9 - Surfaces to be added the spot weld set. Each surface can input by a pre-defined node component or by a meshed area.

- SWADD command can be repeated to add more surfaces- Max. number of allowable surfaces (including two from basic set) = 11.

SWADD, Ecomp, SHRD, NCM1, NCM2, NCM3, NCM4, NCM5, NCM6, NCM7, NCM8, NCM9Ecomp - The name of an existing spot weld set which composes contact, target and beam elements for the spot weld definition.SHRD - Search radius. It defaults to 4 times of spot weld radius SWRDNCM1-NCM9 - Surfaces to be added the spot weld set. Each surface can input by a pre-defined node component or by a meshed area.

- SWADD command can be repeated to add more surfaces- Max. number of allowable surfaces (including two from basic set) = 11.

Spot weldsurface 1

Spot weld radius

Spot weld node 1

Spot weldsurface 2

Spot weld node 2

Spot weldsurface 3Spot weld node 3

Basic spot weld setOriginal position of spot weld node 1

Beam2

Beam1

Spot weldsurface 4Spot weld node 4

More surfaces

Beam3


© 2004 ANSYS, Inc.



Mesh-Independent Spot Weld

• SWDEL, Ecomp• Delete spot weld set

- Ecomp - The name of an existing spot weld set.

- If Ecomp = ALL (default) all the spot welds are deleted


© 2004 ANSYS, Inc.




• SWLIST, Ecomp• List spot weld set- Ecomp - The name of an existing

spot weld set.- If Ecomp = ALL (default) all the spot

welds are Listed

• In POST1 not only elements and contact pairs are listed but also output beam results. For deformed BEAM188 both forces/moments and stresses are listed.


© 2004 ANSYS, Inc.




Beam188Beam188

Conta175Conta175

Targ170Targ170Output


Pre-integrated shell/beam sections

Pre-integrated shell/beam sections


© 2004 ANSYS, Inc.



Preintegrated Shell Section

• A,B, D and E sub-matrices are symmetric – Allow only bottom symmetric half to be defined – MT, BT are generalized stresses caused by a fully

constrained unit temperature rise is the current temperature, I is reference temperature• A,B,D,E,MT,BT can be defined at 6 temperatures

independently• Mass Density of shell/unit area may also be defined at 6

temperatures

BT

MT

DB

BA

M

N IT

2

1

2221

1211

2

1

EE

EE

S

S


© 2004 ANSYS, Inc.



Benefits/Limitations

• Benefits– Missing capability for 4

node shells in ANSYS– Faster: no material point

calculations or storage– Third party software

provide the section stiffness for layered, sandwich or other constructions

– Optimization with

homogenized behavior

• Limitations– No output of stresses

• Section resultants (membrane forces and bending moments are available)

– Ability to specify initial stresses is lost

– Linear material behavior– Birth and death is not

supported (currently)– Not meaningful to use at

finite strains • Thickness is not updated

– Offset is not allowed


© 2004 ANSYS, Inc.



Nonlin. Beam General Sections

• We define the “section stiffness” directly as a function of– “section strain” and– Temperature

• There is no material input necessary

• We also define mass density and thermal expansion coefficient– One temp. input per node

(no variation across section)

2

1

2

1

2

1

2

1

2

1

2

1

),(

),(0

),(

),(

0),(

),(

tSF

tSFtQ

tF

tF

tAx

S

S

TM

M

N

CurvatureBen

ding

Mom

ent


© 2004 ANSYS, Inc.



Benefits/Limitations

• Why?– Allows nonlinear

relationships (elastic and elasto-plastic) in terms of generalized stresses and generalized strains

– Very efficient– Allows results from

experiments or another slice analysis as input

• Limitations– No coupling between Axial

and Bending behaviors– Allows nonlinear elastic and

plastic behavior– 20 points of stress-strain

supported– Stress-Strain curve may be

supplied at 6 temperatures– Not applicable for “Warping”

Key-option– Only SMISC quantities are

supported• PRSSOL is meaningless

Beam188/Beam184Beam188/Beam184


Follower ForcesFollower Forces


© 2004 ANSYS, Inc.



Follower load example

P/100P P

Nodal loads

Follower loads


© 2004 ANSYS, Inc.



FOLLW201 element

• A “one” node element – Must be used with nodes that

are attached to shells & beams (uses 6 d.o.f per node)

– No material, section, esys attributes necessary

– Contributes to “stiffness” only for NLGEOM,ON

• NROPT,UNSYM preferred

• Follower stiffness symmetrized for NROPT,FULL

• Real constants– 6 values

• First three n1,n2,n3 entrees are direction cosines of the force vector

• Next three m1,m2,m3 entrees are direction cosines of the moment vector

– The vectors defined by real constants will evolve with deformation (follow the displacements)


© 2004 ANSYS, Inc.



Follower loads

• Follower loads are non-conservative

• Introduce unsymmetric load stiffness contributions

• Introduce stability issues; flutter, dynamic stability

• Often counter intuitive and non-predictable

• A simple cantilever with follower load has flutter instabilities

• SFE command is used to specify load magnitude

• FACE 1 – force• FACE 2 – moment

sfe,nel+1,1,pres,1,-load


Nonlinear Diagnostics & Contact

Nonlinear Diagnostics & Contact


© 2004 ANSYS, Inc.



Diagnostic Tool

• Visualization and adjustment tools for initial contact status– CNCHECK, DETAIL: evaluate Contact Pair specifications– CNCHECK, ADJUST: move contact nodes to target to close

gap or reduce penetration – CNCHECK, POST: view contact initial status before solving– CNCHECK, RESET: reset contact default settings


© 2004 ANSYS, Inc.



Diagnostic Tool

• NLDIAG,CONTACT,on– File Jobname.cnd is written during

iteration/substep/loadsetp

– Lists on a pair-based items.

– Identify when and how contact occurs.

– When divergence occurs, it determines the regions where contact is unstable.


Temperature Dependent Curve Fitting

Temperature Dependent Curve Fitting


© 2004 ANSYS, Inc.



Purpose and Experimental Data

• The purpose of the project is to generate coefficients from temperature dependent experimental data.

• This is applicable to all HyperElastic, ViscoElastic(Prony Series) and Implicit Creep models.

• This is an extension of the existing curve fitting capabilities for all the above mentioned material models.

• Add data at various temperatures and as many as you like in the following format. This is applicable to all experimental data types.– (uniaxial, biaxial, volumetric, creep,…)– Example;– /temp,100– 0.0 1– 0.1 2– 0.2 3

• Only one temperature per file.


© 2004 ANSYS, Inc.



New Functionality

• A new option is added to enable temperature dependent curve fitting.

• With the temperature dependent option on, The solver filters experimental data depending on the temperature and generates separate sets of coefficients at corresponding temperatures.

• There are two solution procedures– Set a temperature and solve. Repeat this for all other

temperatures, verify/view the results and save the coefficient to ansys material database.

– Set the temperature to “all” and solve. This will solve for all temperatures at once. Verify/view the results and save to database.

• The plot page plots the curves at all temperatures.


© 2004 ANSYS, Inc.



Step by step procedure

• Import Experimental Data – One temperature per file

• Pick an appropriate material model.• Enable temperature dependent curve fitting

(tbft,set,categ,func,opt,tdep,1)• Solution

– Set the temperature (tbft,set,categ,func,opt,tref,temp1)– Solve– Set the temperature (tbft,set,categ,func,opt,tref,temp2)– Solve ……

Or– Set the temperature (tbft,set,categ,func,opt,tref,all)– Solve command solves for coefficients at all temperatures.

• Verify the results using plots for all temperatures.• Save the data to Ansys database.


© 2004 ANSYS, Inc.



Sample Script

/prep7! Define Materialtbft,fadd,1,hyper,moon,2

! Define Uniaxial Datatbft,eadd,1,unia,unia-100.exptbft,eadd,1,unia,unia-200.exptbft,eadd,1,unia,unia-300.exptbft,eadd,1,unia,unia-400.exp

! Define Volumetric Datatbft,eadd,1,volu,volu-100.exptbft,eadd,1,volu,volu-200.exptbft,eadd,1,volu,volu-300.exptbft,eadd,1,volu,volu-400.expContd ………..

tbft,set,1,hyper,moon,2,tdep,1tbft,set,1,hyper,moon,2,tref,100tbft,solve,1,hyper,moon,2,0tbft,set,1,hyper,moon,2,tref,200tbft,solve,1,hyper,moon,2,0tbft,set,1,hyper,moon,2,tref,300tbft,solve,1,hyper,moon,2,0tbft,set,1,hyper,moon,2,tref,400tbft,solve,1,hyper,moon,2,0atbft,list,1tbft,fset,1,hyper,moon,2tblis,all,allfini


© 2004 ANSYS, Inc.



Temperature Dependent Uniaxial Experimental Data


© 2004 ANSYS, Inc.



Solver Page


© 2004 ANSYS, Inc.



HyperElastic Polynomial –Uniaxial Data Fit at four temperatures


© 2004 ANSYS, Inc.



Saved Coefficients in Ansys Material GUI


Frequency Dependent Harmonic Analysis



© 2004 ANSYS, Inc.




• Objectives– Frequency and temperature dependent elastic

properties– Frequency and temperature dependent damping

coefficient– Calculate damping matrix from elements – Support full harmonic response analysis


© 2004 ANSYS, Inc.




• Equation of motion

FuKuCuM [M] – mass matrix

[K] – stiffness matrix

[C] – damping matrix

))(),(E(KK e

eCC ee K)(sC

s – structure damping coefficient


© 2004 ANSYS, Inc.




– Elasticity• TB,ELASTIC Command

Isotropic elasticity (Ex, NUxy)Orthotropic elasticity (Ex,Ey,Ez,Gxy,Gxz,Gyz,Nuxy,Nuxz,Nuyz)Use TBFIELD to define frequency and temperature dependent elastic properties

– Damping coefficient• TB,SDAMP (SDAMP - stand for structure damping)

Use TBFIELD to define Frequency and temperature dependent damping coefficient

– Element supports• 182, 183, 185, 186, 187 for all stress states


© 2004 ANSYS, Inc.




• Elasticity– The Command– TB,ELASTIC,MAT,NTEMP,NPTS,TBOPT– MAT

• Material number

– NTEMP• Number of temperature

– NPTS• Number of data point• 2 – for isotropic elasticity• 9 – for orthotropic elasticity

– TBOPT : elastic data table option• IEL - isotropic elasticity behavior, the default• OELN - orthotropic elasticity behavior with minor Poisson ratio


© 2004 ANSYS, Inc.




Procedure• Use ANSYS full harmonic analysis procedure

ANTYP,HARM• Parallel to other ANSYS full harmonic analysis with

damping effect through commands such as ALPHA and BETA; MP,DAMP; DMPR; …

• The DAMPING matrix from TB,SDAMP is additive to other damping matrix, and therefore the damping effect is “add on”

• TB,ELASTIC can be used with TB,SDAMP and also MP,DAMP;ALPHA and BETA; DMPR.


© 2004 ANSYS, Inc.




• Example– Define an elastic data table with frequency dependence

TB,ELASTIC,1, ,2 ! Elastic data tableTBFIELD , FREQ,25 ! First frequency valueTBFIELD , TEMP,25 ! First temperature valueTBDATA,1,2.50e11,0.3 ! E and TBFIELD ,FREQ,50 ! Second frequency valueTBDATA,1,2.0e11,0.3TBFIELD ,TEMP,50 ! Second temperature valueTBFIELD ,FREQ,75 ! Third frequency valueTBDATA,1,1.5e11,0.3TBFIELD ,FREQ,100 ! Forth frequency valueTBDATA,1,1.0e11,0.3


© 2004 ANSYS, Inc.




• Example– Define a damping coefficient data table with frequency

dependence TB,SDAMP,1, ,1 ! damping data tableTBFIELD , FREQ,25 ! First frequency valueTBFIELD , TEMP,25 ! First temperature valueTBDATA,1, 0.2 ! Damping co.TBFIELD ,FREQ,50 ! Second frequency valueTBDATA,1, 0.19TBFIELD ,TEMP,50 ! Second temperature valueTBFIELD ,FREQ,75 ! Third frequency valueTBDATA,1, 0.18TBFIELD ,FREQ,100 ! Forth frequency valueTBDATA,1, 0.17


© 2004 ANSYS, Inc.




• SOLUTION procedure– /SOLUTION– ANTYPE,HARMIC ! Harmonic response

analysis– HROPT,FULL ! Full harmonic response– HROUT,OFF ! Turn off printout– HARFRQ,25,400 ! Frequency range– NSUB,16,,16


© 2004 ANSYS, Inc.




Cantilever beam subject to uniform pressure

0.0E+00

5.0E+10

1.0E+11

1.5E+11

2.0E+11

2.5E+11

3.0E+11

0 100 200 300 400

Young's modulus as function of frequency

Material Properties

Damping coefficient as function of frequency

0

0.05

0.1

0.15

0.2

0.25

0 100 200 300 400


© 2004 ANSYS, Inc.



0.0E+00

2.0E-07

4.0E-07

6.0E-07

8.0E-07

1.0E-06

1.2E-06

0 100 200 300 400 500

Results from FDM

Expected results


• Comparison of displacement

di

NoteReference solution is obtained by defining material properties with the

corresponding frequency at every load step


QR Damp EigensolverQR Damp Eigensolver


© 2004 ANSYS, Inc.



• In CAE applications where structural dynamic response of non-conservative systems need evaluated we encounter a structural stiffness matrix that may be non-symmetric.

• Example: Non-symmetric stiffness contributions resulting from friction forces between contact surfaces.

•Suited for Brake Friction models and other applications such as rotor-dynamic stability investigations, et al.

•The QR damp mode extraction method has been extended to account for non-symmetric stiffness matrices in Modal Analysis.

MODOPT, QRDAMP, n

QR Damp Eigensolver


© 2004 ANSYS, Inc.



• Initially, any element contributing non-symmetric [K] is symmetrized and a Block Lanczos eigensolution performed

• Then, in a second pass, non-symmetric element stiffness contribution is projected onto the modal subspace.

• Finally, the reduced non-symmetric quadratic eigenproblem is solved in the modal subspace.

• Much faster and requires lesser computational resources than the existing DAMP or UNSYM eigensolvers

•Designed to handle a globally non-symmetric [K] where the unsymmetry is a result of only a few non-symmetric elements in the model

QR Damp Eigensolver: Procedure


© 2004 ANSYS, Inc.



• When complex eigenvalues are present the eigenvectors will be complex• QR damp mode extraction method now extracts complex eigenvectors when requested. • QR damp solver is supported in partial solutions module (PSOLVE ) to account for non-linear pre-stress (NLGEOM, ON and PSTRES, ON) effects• Useful in applications such as brake friction modeling with contact elements, CONTA178, for example.• To retain the non-symmetric [K] in PSOLVE modal analysis set NROPT, UNSYM in the preceding static pre-stress analysis part

MODOPT, QRDAMP, n, , , cpxmode

cpxmode = YES -> extract complex modes

QR Damp Eigensolver

PSOLVE, EIGQRDA


© 2004 ANSYS, Inc.



Simple Brake Model

/SOLantype,statictime,1outres,nsol,allautots,-1nsubst,1,10,1ematwr,yes

allselPSTR,ONNLGEOM,ONNROP,UNSYMcnvtol,u,,0.001SOLVEFINISH

/soluantype,modalmodopt,qrda,10,,, onmxpand,10pstr,onpsolve,eigqrdapsolve,eigexpfini


© 2004 ANSYS, Inc.



Brake Model – Freqs.

*** UNDAMPED FREQUENCIES FROM BLOCK LANCZOS ITERATION ***

MODE FREQUENCY (HERTZ)

1 0.2010123605524

2 0.2359842118663

3 0.2473789086098

4 0.2649397833890

5 0.2834619725598

6 0.2908635371466

7 0.3179868238312

8 0.3591154172295

9 0.3667578353825

10 0.5055839775250

*** WARNING *** CP = 0.000 TIME= 00:00:00

Eigenfrequencies from Block Lanczos eigensolution have been obtained by symmetrizing non-symmetric stiffness matrix coefficients. In the downstream QR damp eigensolution full non-symmetric stiffness matrix will be used.

***** DAMPED FREQUENCIES FROM REDUCED DAMPED EIGENSOLVER *****

MODE CPX FREQ (HERTZ) MODAL DAMP RATIO

1 0.0000000 0.23599942 j 0.0000000

0.0000000 -0.23599942 j 0.0000000

2 0.0000000 0.26950444 j 0.0000000

0.0000000 -0.26950444 j 0.0000000

3 0.0000000 0.30163581 j 0.0000000

0.0000000 -0.30163581 j 0.0000000

4 0.0000000 0.34132210 j 0.0000000

0.0000000 -0.34132210 j 0.0000000

5 0.0000000 0.58554351 j 0.0000000

0.0000000 -0.58554351 j 0.0000000

6 ……

7 ……

Brake Model


Local CYS for function BC’sLocal CYS for function BC’s


© 2004 ANSYS, Inc.



• Post1 surface calculations- New “Cylinder” surface. Creates a cylindrical cut through the model of user specified radius and orientation.

• Map results on to the cylindrical surface to perform calculations

Post1 Surface Calculations


Component based Acceleration

Component based Acceleration


© 2004 ANSYS, Inc.



Component Based Acceleration

• Apply apply inertia forces on different element components, based on the accelerations on the different parts of the structure.

• CMACEL, CM_NAME, CMACELX, CMACELY, CMACELZ– CM_NAME The name of the element component – CMACELX, CMACELY, CMACELZ – Linear acceleration of the element component

CM_NAME in the global Cartesian X, Y, and Z axis directions, respectively.


© 2004 ANSYS, Inc.



Example

/prep7…nsel,s,loc,z,0,-72esln,,1cm,roof1,elemnsel,s,loc,z,-75,-140esln cm,roof2,elem nsel,s,loc,z,-150,-220esln,,1cm,roof3,elemnsel,s,loc,z,-225,-300eslncm,roof4,elemesel,allnsel,alFini

/soluantype,staticcmacel,roof1,,0.36cmacel,roof2,,0.37cmacel,roof3,,0.38cmacel,roof4,,0.39solvefini


CMS - SuperelementsCMS - Superelements


© 2004 ANSYS, Inc.



Expansion in transformed location

• Expand the substructure results in transformed location if SETRAN or SESYMM command is applied in USE pass.

• SEEXP, Sename, Usefil, Imagky, Expopt– Expopt: Key to specify whether the

superelement expansion pass • RSTOFF, Lab, OFFSET

– Offsets node or element IDs in the FE geometry record.


© 2004 ANSYS, Inc.



Example

!left wing is from right wing in USE pass/prep7et,1,50se,RightWing sesymm, LeftWing, X, 100, se2, subse,se2cp,...fini

! expansion Pass /assign,rst,rightwing,rst/solutionexpass,onseexp,rightwing,use, ,onrstoff, node, nof2rstoff, elem, eof2numexp,allsolvefinish


© 2004 ANSYS, Inc.



CMSFILE command enhancement

• Handle the CMS result file, but also other types of result file. So, the user can keep FEM parts in CMS analysis and postprocess the substructure expanded result files and FEM result files together.

• CMSFILE, Option, Fname, Ext, CmsKey• CmsKey

– Valid only when adding a results file (Option = ADD or ALL), this key specifies whether or not to check the specified .rst file to determine if it was created via a CMS expansion pass:

– ON — Check (default).– OFF — Do not check.


Thermal Radiation Enhancements

Thermal Radiation Enhancements


© 2004 ANSYS, Inc.



Radiosity Solution Enhancements

• Post Process radiation data via SURF251/252 element types• Efficient solution for fine surface meshes via

decimation/agglomeration• Efficient solution for models with symmetry planes• Features

– Decimation of thermal mesh– Planar Symmetry– Cyclic Symmetry


© 2004 ANSYS, Inc.



Radiosity Solution Enhancements

• The following new commands allow generation of SURF251/252 elements:– RDEC : This specifies decimation parameters for coarsening– RSYM: allows user to define symmetry parameters– RSURF: action command to generate the surface elements

• Use the NMISC records of SURF251/252 Elements to print /display the following:– area of each surface element– temperature of surface element– emissivity of surface element– enclosure # of surface element– net radiation heat flux leaving surface element


© 2004 ANSYS, Inc.



Planer and Cyclic Symmetry

POS(plane of symmetry) specified by user via CS

command

COR(center of rotation) specified by user via CS

command

1 reflection only

2 repetitions

original

original

Reflection is NOT the same as Repetition !!!

ansys, inc. proprietary © 2004 ansys, inc. chapter 1 ansys release 9.0

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