transient dynamic analysis in ansys

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Chapter 5: Transient Dynamic Analysis

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5.1 Definition of Transient Dynamic Analysis

Transient d%na&i' anal%sis (so&eti&es 'alled ti&e)histor% anal%sis is a te'hni+ue used to deter&ine

the d%na&i' response of a stru'ture under the a'tion of an% ,eneral ti&e)dependent loads- .ou 'an

use this t%pe of anal%sis to deter&ine the ti&e)var%in, displa'e&ents/ strains/ stresses/ and for'es in astru'ture as it responds to an% 'o&bination of stati'/ transient/ and har&oni' loads- The ti&e s'ale ofthe loadin, is su'h that the inertia or da&pin, effe'ts are 'onsidered to be i&portant- If the inertia andda&pin, effe'ts are not i&portant/ %ou &i,ht be able to use a stati' anal%sis instead (see Chapter 2-

The basi' e+uation of &otion solved b% a transient d%na&i' anal%sis is

0here

M &ass &atrix

C da&pin, &atrix stiffness &atrix

nodal a''eleration ve'tor nodal velo'it% ve'tor

6u7 nodal displa'e&ent ve'tor

68(t7 load ve'tor

9t an% ,iven ti&e/ t/ these e+uations 'an be thou,ht of as a set of :stati': e+uilibriu& e+uations that

also ta;e into a''ount inertia for'es (M and da&pin, for'es (C - The 9N9= Chapter 5 Transient @%na&i' 9nal%sis (?P1##"$"1"

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Graphical User Interface (GUI) to build and solve models no matter what type of analysis you aredoing.

Section 5.8 !Sample "ransient #ynamic $nalysis (%ommand or &atch 'ethod)! shows you theseuence of commands you would issue (either manually or while running $S*S as a batch +ob) to

perform an e,ample transient dynamic analysis. Section 5.- !Sample "ransient #ynamic $nalysis

(GUI 'ethod)! shows you how to e,ecute the same sample analysis using menu choices from the

$S*S GUI. ("o learn how to use the commands and GUI selections for building models read theANSYS Modeling and Meshing Guide.)

or detailed alphabeti/ed descriptions of the $S*S commands see the ANSYS Commands

Reference.

5.3 Preparing for a Transient Dynamic Analysis

$ transient dynamic analysis is more involved than a static analysis because it generally reuires

more computer resources and more ofyourresources in terms of the !engineering! time involved.

*ou can save a significant amount of these resources by doing some preliminary wor0 to understandthe physics of the problem. or e,ample you can1

2. $naly/e a simpler model first. $ model of beams masses and springs can provide good insight

into the problem at minimal cost. "his simpler model may be all you need to determine the dynamic

response of the structure.

3. If you are including nonlinearities try to understand how they affect the structure4s response bydoing a static analysis first. In some cases nonlinearities need not be included in the dynamic

analysis.

. Understand the dynamics of the problem. &y doing a modal analysis which calculates the naturalfreuencies and mode shapes you can learn how the structure responds when those modes are

e,cited. "he natural freuencies are also useful for calculating the correct integration time step.

6. or a nonlinear problem consider substructuring the linear portions of the model to reduce analysis

costs. Substructuring is described in theANSYS Advanced Analysis Techniques Guide.

5.4 The Three Solution Methods

"hree methods are available to do a transient dynamic analysis1 full reducedand mode

superposition. "he $S*S7inear9lus program allows only the mode superposition method. &eforewe study the details of how to implement each of these methods let4s e,amine the advantages and

disadvantages of each.

5.4.1 The Full Method

"hefull methoduses thefullsystem matrices to calculate the transient response (no matri, reduction).It is the most powerful of the three methods because it allows all types of nonlinearities to be included

(plasticity large deflections large strain etc.).

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Note-If you do not want to include any nonlinearities, you should consider using one of the othermethods because the full method is also the most expensive method of the three.

The advantages of the full method are:

It is easy to use, because you don't have to worry about choosing master degrees of freedom or

mode shapes.

It allows all types of nonlinearities. It uses full matrices, so no mass matrix approximation is involved.

ll displacements and stresses are calculated in a single pass. It accepts alltypes of loads: nodal forces, imposed !non-"ero# displacements !although not

recommended#, and element loads !pressures and temperatures#.

It allows effective use of solid-model loads.

The main disadvantage of the full method is that it is more expensive than either of the other methods.

5.4.2 The Reduced Method

The reduced methodcondenses the problem si"e by using master degrees of freedom and reduced

matrices. fter the displacements at the master $%& have been calculated, ()( expands thesolution to the original full $%& set. !(ee (ection *.+, !atrix eduction,/ for a more detailed

discussion of the reduction procedure.# The advantages of the reduced method are:

It is faster and less expensive than the full method.

The disadvantages of the reduced method are:

The initial solution calculates only the displacements at the master $%&. second step, 0nown

as the expansion pass, is re1uired for a complete displacement, stress and force solution.

!2owever, the expansion pass might not be needed for some applications.# 3lement loads !pressures, temperatures, etc.# cannot be applied. ccelerations, however, are

allowed.

ll loads must be applied at user-defined master degrees of freedom. !This limits the use ofsolid-model loads.#

The time step must remain constant throughout the transient, so automatic time-stepping is not

allowed.

The only nonlinearity allowed is simple node-to-node contact !gap condition#.

5.4.3 The Mode Superposition Method

The mode superposition methodsums factored mode shapes !eigenvectors# from a modal analysis tocalculate the structure's response. This is the only method available in the ()(45inear6lus

program. Its advantages are:

It is faster and less expensive than the reduced or the full method for many problems.

3lement loads applied in the preceding modal analysis can be applied in the transient dynamicanalysis via the LVSCALEcommand.

It accepts modal damping !damping ratio as a function of mode number#.

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The disadvantages of the mode superposition method are:

The time step must remain constant throughout the transient, so automatic time-stepping is notallowed.

The only nonlinearity allowed is simple node-to-node contact (gap condition).

It should not be used for a floating or dis!oint structure.

"hen you are using #ower$ynamics, initial conditions may not have previously-applied loads

or displacements. %or further information, see &ection '..*.*, +btaining the &olution. It does not accept imposed (non-ero) displacements.

5.5 How to Do a Transient Dynamic Analysis

"e will first describe how to do a transient dynamic analysis using the full method. "e will then list

the steps that are different for the reduced and mode superposition methods.

5.5.1 Full Transient Dynamic Analysis

The procedure for a full transient dynamic analysis (available in the &/&01ultiphysics,&/&01echanical, and &/&0&tructural products) consists of three main steps:

. 2uild the model.

*. pply loads and obtain the solution.

3. 4eview the results.

5.5.2 Build the Model

In this step, you specify the !obname and analysis title and then use #45#6 to define the element

types, element real constants, material properties, and the model geometry. These tas7s are commonto most analyses. TheANSYS Modeling and Meshing Guidee8plains them in detail.

5.5.2.1 Points to Remember

/ou can use both linear and nonlinear elements.

2oth /oung9s modulus (5) (or stiffness in some form) and density ($5&) (or mass in some

form) must be defined. 1aterial properties may be linear or nonlinear, isotropic or orthotropic,and constant or temperature-dependent.

&ome comments on mesh density:

The mesh should be fine enough to resolve the highest mode shape of interest. 4egions where stresses or strains are of interest re;uire a relatively finer mesh than regions

where only displacements are of interest.

If you want to include nonlinearities, the mesh should be able to capture the effects of thenonlinearities. %or e8ample, plasticity re;uires a reasonable integration point density (and

therefore a fine element mesh) in areas with high plastic deformation gradients.

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If you are interested in wave propagation effects (for e8ample, a bar dropped e8actly on itsend), the mesh should be fine enough to resolve the wave. rule of thumb is to have at least *

elements per wavelength along the direction of the wave.

5.5.3 Apply Loads and Obtain the Solution

In this step, you define the analysis type and options, apply loads, specify load step options, andinitiate the finite element solution. $etails of how to do these tas7s are e8plained below.

. 5nter the &/& solution processor.

>ommand(s):

/SOLU

C=I:

Main Menu>Solution

*. $efine the analysis type and analysis options. &/& offers these options for a transient dynamicanalysis:

Table 5-1 Analysis types and analysis options

Option Command U! "ath

ew nalysis A#T$"% Main Menu>Solution>-Analysis Type-#e& Analysis

nalysis Type:

Transient $ynamic A#T$"%Main Menu>Solution>-Analysis Type-#e& Analysis>

T'ansient (ynami)

&olution 1ethod T*#O"T Main Menu>Solution>Analysis Options

1ass 1atri8%ormulation

LUM"M Main Menu>Solution>Analysis Options

?arge $eformation5ffects

#L%OM Main Menu>Solution>Analysis Options

&tress &tiffening5ffects

SST!+ Main Menu>Solution>Analysis Options

ewton-4aphson

+ption#*O"T Main Menu>Solution>Analysis Options

5;uation &olver %,SL Main Menu>Solution>Analysis Options

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Each of these options is explained in detail below.

5.5.3.1 Option: New Analysis [ANTYPE]

Choose new analysis. A restart is applicable if (a) you have previously completed a static prestress or

a full transient dynamic analysis and you want to extend the time-history, or (b) you want to restart afailed nonlinear analysis. (The filesJobname.EAT,Jobname.E!A", andJobname.#$ from the

initial run must be available for the restart. %esults will be appended to the initial results file

(Jobname.%!T), if available.)

5.5.3.2 Option: Analysis Type [ANTYPE]

Choose Transient #ynamic.

5.5.3.3 Option: Solution Metho [T!NOPT]

Choose full (default), reduced, or mode superposition method. The procedure for the reduced and

mode superposition methods is explained later in this chapter.

5.5.3." Option: Mass Mat#i$ %o#&ulation ['(MPM]

&e recommend the default formulation for most applications. 'owever, for some problems involvin

s*inny structures, such as slender beams or very thin shells, the lumped mass approximation miht

provide better results. Also, the lumped mass approximation can result in a shorter run time and lower

memory re+uirements.

#efault (which is element dependent) umped ass Approximation

To specify the remainin analysis options usin the /0, clic* 12 in the Transient Analysis dialobox.

5.5.3.5 Option: 'a#)e *e+o#&ation E++e,ts [N'-EOM]

Choose 13 only if you expect lare deflections (as in the case of a lon, slender bar under bendin)

or lare strains (as in a metal-formin problem). are deflections and lare strains are eometric

nonlinearities and are described in Chapter 4. $y default, small deflections and small strains areassumed.

5.5.3. Option: St#ess Sti++enin) E++e,ts [SST/%]

Choose 13 in the followin situations (default is 13 when N'-EOM and SO'0ONT!O'are

13).

0f, in a small deflection analysis, you expect the stress in the structure to sinificantly increase

(or decrease) its stiffness, such as a thin circular membrane under normal pressure.

0f you need it to help converence in a lare deflection analysis.

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Stress stiffening is a geometric nonlinearity and is described in Chapter 8.

5.5.3.7 Option: Newton-Raphson Option [NROPT]

This option specifies how often the tangent matrix is updated during solution and is used only if

nonlinearities are present. Choose from the options listed below. See Chapter 8for details.

Program-chosen (default !ull

"odified

#nitial Stiffness

5.5.3.8 Option: Equation Solve [E!S"#]

Specify one of these sol$ers%

!rontal sol$er (default for linear analysis

&acobi Con'ugate radient (&C sol$er &C out-of-memory sol$er

#ncomplete Choles)y Con'ugate radient (#CC sol$er

Preconditioned Con'ugate radient (PC sol$er PC out-of-memory sol$er

#terati$e (auto-select* for linear static+full transient structural or steady-state+transient thermal

analyses only (recommended

Sparse (SP, sol$er (default for nonlinear analysis when SO"$ONTRO"is /

!or large models (high wa$efronts0 we recommend the PC sol$er.

1. ,pply loads on the model.

, transient analysis0 by definition0 in$ol$es loads that are functions of time. To specify such

loads0 you need to di$ide the load-$ersus-time cur$e into suitable load steps. 2ach 3corner3 onthe load-time cur$e may be one load step0 as shown in !igure 4-5.

%i&ue 5-' E(a)ples o* loa+-vesus-ti)e ,uves

The first load step you apply is usually to establish initial conditions. 6ou then specify the loadsand load step options for the subse7uent transient load steps. !or each load step0 you need to

specify both load $alues and time $alues0 along with other load step options such as whether to

step or ramp the loads0 use automatic time stepping0 etc. 6ou then write each load step to a fileand sol$e all load steps together.

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Apply Initial Conditions

The first step in applying transient loads is to establish initial conditions (that is, the conditionat Time = 0). A transient dynamic analysis requires two sets of initial conditions (because the

equations being solved are of second order) initial displacement ( ) and initial velocity ( ). !fno special action is ta"en, both and are assumed to be #ero. ) are

always assumed to be zero,but you can specify non#ero initial accelerations by applying

appropriate acceleration loads over a small time interval.

The following paragraphs describe how to apply different combinations of initial conditions.

Zero initial displacement and zero initial velocity$These are the default conditions, that is, if

= = 0, you don%t need to specify anything. &ou may apply the loads corresponding to the firstcorner of the load$versus$time curve in the first load step.

Nonzero initial displacement and/or nonzero initial velocity$&ou can set these initial conditions

with the ICcommand.

'ommand(s)

IC

!

Main Menu>Solution>-Loads-Apply>Initial Condit'n>Define

Caution: *e careful not to define inconsistent initial conditions. +or instance, if you define aninitial velocity at a single -+, the initial velocity at every other -+ will be 0.0, potentiallyleading to conflicting initial conditions. !n most cases, you will want to define initial conditions

at every unconstrained -+ in your model. !f these conditions are not the same at every -+,

it is usually much easier to define initial conditions eplicitly, as documented below.

/ee theANSYS Commands e!erencefor a discussion of the TIMINTand ICcommands.

Zero initial displacement and nonzero initial velocity$The non#ero velocity is established by

applying small displacements over a small time interval on the part of the structure wherevelocity is to be specified. +or eample if = 0.1, you can apply a displacement of 0.002 over

a time interval of 0.003, as shown below.

...

TIMINT,OFF ! Time integration effects off

D,ALL,UY,.001 ! Small UY isl. "ass#ming Y$irection %elocit&'

TIM(,.00) ! Initial %elocit& * 0.001+0.00) * 0.-LS/IT( ! rite loa ata to loa ste file "Jobname.S01'

DD(L,ALL,UY ! /emo%e imose islacements

TIMINT,ON ! Time integration effects on

...

Nonzero initial displacement and nonzero initial velocity$This is similar to the above case,

ecept that the imposed displacements are actual values instead of 4small4 values. +or eample,

if = 2.0 and = .1, you would apply a displacement of 2.0 over a time interval of 0.3

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...

TIMINT,OFF ! Time integration effects off

D,ALL,UY,1.0 ! Initial dislacement 1.0

TIM",.# ! Initial $elocit% 1.0&0.# '.(

L)*+IT" ! *rite load data to load ste file Jobname.)01-

DD"L",ALL,UY ! +emo$e imosed dislacements

TIMINT,ON ! Time integration effects on

...

Nonzero initial displacement and zero initial velocity-This requires the use of two substeps[NSUBST,2] with astepchange in imposed displacements [KBC,1]. Without the step change(or with ust one substep!, the imposed displacements would "ar# directl# with time, leading to

a nonzeroinitial "elocit#. The e$ample below shows how to appl# % 1.& and % &.&'

...

TIMINT,OFF ! Time integration effects off for static soltion

D,ALL,UY,1.0 ! Initial dislacement 1.0

TIM",.001 ! )mall time inter$al

N)U/)T,' ! To sstes

2/3,1 ! )teed loads


! Transient soltionTIMINT,ON ! Time4integration effects on for transient soltion

TIM",... ! +ealistic time inter$al

DD"L",ALL,UY ! +emo$e dislacement constraints

2/3,0 ! +amed loads if aroriate-

! 3ontine it5 normal transient soltion rocedres

...

Nonzero initial acceleration-This can be appro$imated b# specif#ing the required acceleration[ACEL] o"er a small inter"al of time. or e$ample, the commands to appl# an initial

acceleration of ).*1 would loo+ li+e this'

...

A3"L,,6.71 ! Initial Y4direction acceleration

TIM",.001 ! )mall time inter$al

N)U/)T,' ! To sstes

2/3,1 ! )teed loads


! Transient soltion

TIM",... ! +ealistic time inter$al

DD"L",... ! +emo$e dislacement constraints if aroriate-

2/3,0 ! +amed loads if aroriate-

! 3ontine it5 normal transient soltion rocedres

...

ee theANSYS Commands e!erencefor a discussion of the ACEL, TIME, NSUBST, KBC,

LSWRITE, DDELEand KBCcommands.

Apply Loads for the Transient Loading ortion

Table -2summaries the loads applicable to a transient d#namic anal#sis. /$cept for inertia loads,

#ou can define loads either on the solid model (+e#points, lines, and areas! or on the finite elementmodel (nodes and elements!. or a general discussion of solid-model loads "ersus finite-elementloads, see 0hapter 2of theANSYS "asic Analysis #rocedures $uide.

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You can also apply complex boundary conditions by defining a 1-dimensional table (TABLE typearray parameter). ee !Applying Loads "sing TABLE Type Array #arameters! in ection $.%.$.&.

Table 5-2 Loads applicable in a transient dynamic analysis

Load Type CategoryCmd

FamilyGUI Path

'isplacement (" "Y "*+,T +,TY +,T*)

onstraints DMain Men!"oltion!-Loads-

#pply!-"trctral- Displacement

orce /oment ( Y */ /Y /*)

orces FMain Men!"oltion!-Loads-

#pply!-"trctral- Force$Moment

#ressure (#+E)urface

Loads"F

Main Men!"oltion!-Loads-

#pply!-"trctral- Pressre

Temperature (TE/#)luence (L"E)/oisture ontent (/0)

Body Loads %FMain Men!"oltion!-Loads-

#pply!-"trctral- Temperatre

ra2ity pinning etc.3nertiaLoads

-Main Men!"oltion!-Loads-

#pply!-"trctral- &ther

3n an analysis loads can be applied remo2ed operated on or listed.

5'5'(') #pplying Loads Using Commands

Table %-&lists all t4e commands you can use to apply loads in a transient dynamic analysis.

Table 5-( Load commands *or a transient dynamic analysis

Load Type

"olid

Model

or F+

+ntity #pply Delete List &perate#pply

"ettings

'isplace-

ment

olid

/odel5eypoints D, D,D+L+ D,LI"T DT#. -

olid

/odelLines DL DLD+L+ DLLI"T DT#. -

olid

/odelAreas D# D#D+L+ D#LI"T DT#. -

inite

Elem

0odes D DD+L+ DLI"T D"C#L+ D"/MDCUM

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Force

SolidModel

Keypoints FK FKDELE FKLIST FTRAN -

Finite

ElemNodes F FDELE FLIST FSCALE FCUM

Pressure

SolidModel

Lines SFL SFLDELE SFLLIST SFTRAN SFGRAD

Solid

ModelAreas SFA SFADELE SFALIST SFTRAN SFGRAD

Finite

ElemNodes SF SFDELE SFLIST SFSCALE

SFGRAD

SFCUM

Finite

Elem Elements SFE SFEDELE SFELIST SFSCALE

SFGRAD

SFBEAM

SFFUN

SFCUM

TemperatureFluence

Solid

ModelKeypoints BFK BFKDELE BFKLIST BFTRAN -

Solid

ModelLines BFL BFLDELE BFLLIST BFTRAN -

Solid

Model

Areas BFA BFADELE BFALIST BFTRAN -

Solid

ModelVolumes BFV BFVDELE BFVLIST BFTRAN -

Finite

ElemNodes BF BFDELE BFLIST BFSCALE BFCUM

Finite

ElemElements BFE BFEDELE BFELIST BFSCALE BFCUM

Inertia - -

ACEL

OMEGA

DOMEGA

CGLOC

CGOMGA

DCGOM IRLF

- - - -

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5.5.3.10 Applying Loads Using the GUI

All loading operations (except List; see below) are accessed through a series of cascadingmenus. From the Solution menu, you select the operation (apply, delete, etc.), then the load type

(displacement, force, etc.), and then the obect to which you are applying the load (!eypoint,

line, node, etc.).

For example, to apply a displacement load to a line, follow this "#$ path%

"#$%

Main Menu>Solution>-Loads-Apply>-Structural-isplace!ent>"n lines

5.5.3.11 Listing Loads

&o list existing loads, follow this "#$ path%

"#$%

Utility Menu>List>Loads>load type

Applying Load Steps #or the $ransient Loading %ortion

&he following load step options are a'ailable for a transient dynamic analysis%

$a&le 5-' Load step options #or a transient dyna!ic analysis

"ption (o!!and GUI %ath

yna!ics "ptions

&ime $ntegration

ffects$IMI)$

Main Menu>Solution>-Load Step "pts-

$i!e*+re,uenc>$i!e Integration

&ransient $ntegration

arameters$I)$%


$i!e*+re,uenc>$i!e Integration

*ampingAL%A /$A

M% AM%


$i!e*+re,uenc> a!ping

General "ptions

&ime $IM/


$i!e*+re,uenc>$i!e $i!e Stepor $i!e Su&steps

Stepped or +amped

Loads2(

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Main Menu>Solution>-Load Step Opts-

Time/Frequenc>Time & Time Stepor Time &

Substeps

Integration Time StepNSUBST

DLT!M


Time/Frequenc>Time & Substepsor Time & TimeStep

Automatic TimeStepping

"UTOTS


Time/Frequenc>Time & Substepsor Time & TimeStep

Nonlinear Options

Max. No. ofEquilibrium Iterations

N#!TMain Menu>Solution>-Load Step Opts-Nonlinear>

quilibrium !ter

ConvergenceTolerances

$N%TOL Main Menu>Solution>-Load Step Opts-Nonlinear>$oner'ence $rit

PredictorCorrector

!ption()D

Main Menu>Solution>-Load Step Opts-Nonlinear>

(redictor

"ine Searc# !ption LNS)$*Main Menu>Solution>-Load Step Opts-Nonlinear>

Line Searc+

Creep Criteria $)(L!MMain Menu>Solution>-Load Step Opts-Nonlinear>

$reep $riterion

Solution Termination

!ptionsN$N%

Main Menu>Solution>-Load Step Opts-Nonlinear>

$riteria to Stop

Output $ontrol Options

Printed !utput OUT()Main Menu>Solution>-Load Step Opts-Output

$trls> Solu (rintout

$atabase and %esults

&ile !utputOUT)S

Main Menu>Solution>-Load Step Opts-Output

$trls> DB/ )esults File

Extrapolation of

%esults)S,

Main Menu>Solution>-Load Step Opts-Output

$trls> !nte'ration (t

...01 D2namics Options

$'namic options include t#e follo(ing)

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Time Integration Effects[T!M!NT]

Time integration effects mustbe turned on for inertia and damping effects to be included in theanalysis (otherwise a static solution is performed). The default is to include time integrationeffects. This option is useful to begin a transient from an initial static solution; that is, the first

load steps are solved with the time integration effects off.

Transient Integration Parameters[T!NT(]

Transient integration parameters control the nature of the ewmar! time integration techni"ue.

The default is to use the constant average acceleration scheme; see yourANSYS Theory

Referencefor further details.

Damping

#amping in some form is present in most structures and should be included in your analysis.

$ou can specify four forms of damping in a full transient dynamic analysis%

&lpha (mass) damping ["L(*"D] 'eta (stiffness) damping [BT"D]

aterialdependent beta damping [M(,#&*]

+lement damping (-'/, etc.)

0ee 0ection 1.23.4, 5#amping,"later in this chapter for further details.

...0 3eneral Options

6eneral options include the following%

Time[T!M]

This option specifies time at the end of the load step.

Stepped or Ramped Loads[4B$]

This option indicates whether to ramp the load change over the load step [4B$] or to stepapply the load change [4B$,2]. The default is ramped for static analysis and stepped for full

transient analysis when SOL$ONT)OLis -.

Integration Time Step[DLT!Mor NSUBST]

The integration time step is the time increment used in the time integration of the e"uations ofmotion. $ou can specify it directly [DLT!M] or indirectly, in terms of the number of substeps

[NSUBST]. The time step si7e determines the accuracy of the solution% the smaller its value,the higher the accuracy. $ou should consider several factors in order to calculate a 5good5

integration time step; see 0ection 1.23.2, 56uidelines for ntegration Time 0tep,5 for details.

Automatic Time Stepping["UTOTS]

This option, also !nown as timestep optimi7ation in a transient analysis, increases or decreases

the integration time step based on the response of the structure. 8or most problems, we

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recommend that you turn on automatic time stepping, with upper and lower limits for theintegration time step. These limits, specified using DELTIMor NSUBST, help to limit the

range of variation of the time step; see Section 5.12.2, "Automatic Time Stepping" for moreinformation. The default is ! when SOLCONTROLis !. therwise, it is .

5.5.3.14 Nonlinear Options

!onlinear options are used only if nonlinearities are present #plasticity, contact elements, creep, etc.$

and include the following%

& Maimum Num!er of Eui#i!rium Iterations'NEQIT(& $on%ergence To#erances'CNVTOL(

& Predictor&$orrector 'ption'RED(

& Line Search 'ption'LNSRC!(

& $reep $riteria'CRLIM(& So#ution Termination 'ptions'NCNV(

or more details, see )hapter *.

5.5.3.15 O"tp"t Control Options

utput control options include the following%

& Printed 'utput'OUTR(

+se this option to include any results data on the output file #(o!name.+T$.

& Data!ase and Resu#ts )i#e 'utput 'OUTRES(

This option controls the data on the results file #(o!name*ST$; see caution -elow.

& Etrapo#ation of Resu#ts 'ERES#(

+se this option to review element integration point results -y copying them to the nodes instead

of etrapolating them #default$.

Ca"tion$/y default, only the last su-step #time0point$ is written to the results file in a full transient

dynamic analysis. To write all su-steps, set the field on the OUTREScommand to A33. Also,a maimum of 1444 su-steps are written to the results file -y default. +se the

command %CON&I',!S to increase the limit #see )hapter 1, "6emory 6anagement and

)onfiguration," of theANSYS +asic Ana#ysis Procedures ,uide$.

Ca"tion$7roper use of multiple OUTRESor OUTRcommands can sometimes -e a little tric8y.

See Section 2.9.:, "utput )ontrols," of theANSYS +asic Ana#ysis Procedures ,uidefor moreinformation on how to use these commands.

An eample load step file is shown -elow%

TIME,... ! Time at the end of 1st transient load step

Loads ... ! Load values at above time

KBC,... ! Stepped or ramped loads

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LSWRITE ! Write load data to load step file

TIME,... ! Time at the end of 2nd transient load step


K,... ! Stepped or ramped loads

LSWRITE ! Write load data to load step file

TIME,... ! Time at the end of "rd transient load step


K,... ! Stepped or ramped loads

LSWRITE ! Write load data to load step fileEt#.

See theANSYS Commands Referencefor a discussion of the TIME, KBCand LSWRITEcommands.

4. Save the load configuration for this step to the load step file.

Command(s):

LSWRITE

GUI:

Main Menu>Solution>Write LS File

Repeat steps .and 4 for each corner of the load!versus!time curve. "ou ma# also $ant to havean additional load step that e%tends past the last time point on the curve to capture the response

of the structure after the transient loading.

&. Save a 'ac!up cop# of the data'ase to a named file. "ou can then retrieve #our model '# re!

entering the *S"S program and issuing RESUME.

Command(s):

SAVE

GUI:

Utility Menu>File>Save as

+. Start the transient solution. or additional $a#s to create and solve multiple load steps (the arra#parameter method and the multiple SOLVEmethod), see Section .-of theANSYS Basic Analysis

Procedures Guide.

Command(s):

LSSOLVE

GUI:

Main Menu>Solution>-Solve-Fro LS Files

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Command(s):

FINISH

GUI:

Close the Solution menu.

5.5.4 Review the Results

Results from a transient dynamic analysis are written to the structural results file,Jobname.RST. They

consist of the following data, all of which are functions of time:

!rimary data

" #odal dis$lacements (U%, U&, U', RT%, RT&, RT') eri*ed data:

" #odal and element stresses" #odal and element strains

" +lement forces" #odal reaction forces

" etc.

5.5.4.1 Postprocessors

&ou can re*iew these results using either !ST-, the timehistory $ost$rocessor, or !ST/, the

general $ost$rocessor.

!ST- is used to re*iew results at s$ecific $oints in the model as functions of time. !ST/ is used to re*iew results o*er the entire model at s$ecific time$oints.

Some ty$ical $ost$rocessing o$erations for a transient dynamic analysis are e0$lained 1elow. 2or acom$lete descri$tion of all $ost$rocessing functions, see Section 3./of theANSYS Basic Analysis

Procedures Guide.


To re*iew results in !ST- or !ST/, the data1ase must contain the same model for which

the solution was calculated (issue RES!Eif necessary). The results file (Jobname.RST) must 1e a*aila1le.

5.5.4." sin# P$S%2&

!ST- wor4s with ta1les of result item *ersus time, 4nown as variables. +ach variableis assigned areference num1er, with *aria1le num1er / reser*ed for time.

/. efine the *aria1les.

Command(s):

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NSOL(primary data, that is, nodal displacements)

ESOL (derived data, that is, element solution data, such as stresses)

RFORCE(reaction force data)FORCE(total force, or static, damping, or inertia component of total force)

SOLU(time step size, number of equilibrium iterations, response frequency, etc.)

GUI:

Main Menu>TimeHist Postpro>Define Variables

Note-In the reduced or mode superposition methods, only static force is available ith the

FORCEcommand.

!. Graph or list the variables. "y revieing the time#history results at strategic points throughout the

model, you can identify the critical time#points for further $%&' postprocessing.

ommand(s):

PLVR(graph variables)

PRVR, *+'*- (list variables)

GUI:

Main Menu>TimeHist Postpro>!rap" Variables

Main Menu>TimeHist Postpro>List Variables

Main Menu>TimeHist Postpro>List E#tremes

$%$%&%& Ot"er Capabilities

-any other postprocessing functions, such as performing math operations among variables, moving

variables into array parameters, and moving array parameters into variables, are available in $%&'!.

&ee hapter of theANSYS Basic Analysis Procedures Guidefor details.

$%$%&%$ Usin' POST(

. ead in model data from the database file%

ommand(s):

RESUME

GUI:

Utilit) Menu>File>Resume from

!. ead in the desired set of results. Use the SETcommand to identify the data set by load step and

substep numbers or by time.

ommand(s):

SET

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GUI:

Main Menu>General Postproc>-Read Results-By Time/Freq

Note-If you specify a time for which no results are available, the results that are stored will be a

linear interpolation between the two nearest time points.

3. Perform the necessary POS! operations. ypical POS! operations are e"plained below.

5.5.4.6 ption! "isplay "e#ormed $%ape

#ommand$s%:

P&"'$P

GUI:

Main Menu>General Postproc>Plot Results>"e#ormed $%ape

heKN!field on P&"'$P&ives you the option of overlayin& the undeformed shape on the

display.

5.5.4.( ption! &ist Reaction Forces and Moments

#ommand$s%:

PRR$&

GUI:

Main Menu>General Postproc>&ist Results>Reaction $olu

he PRR$&command lists reaction forces and moments at the constrained nodes.

o display reaction forces, issue /PB),'(O',,! and then re)uest a node or element display

**P&Tor +P&T+. $Use 'O instead of '(O' for reaction moments.%

5.5.4., ption! &ist *odal Forces and Moments

#ommand$s%:

PR+$&,F$or M%

GUI:

Main Menu>General Postproc>&ist Results>+lement $olution

-ou can list the sum of all nodal forces and moments for a selected set of nodes. Select a set ofnodes and use this feature to find out the total force actin& on those nodes:

#ommand$s%:

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FSUM

GUI:

Main Menu>General Postproc>Nodal Calcs>Total Force Sum

You can also check the total force and total moment at each selected node. For a body in

equilibrium, the total load is zero at all nodes except here an applied load or reaction loadexists.

!ommand"s#:

NFORCE

GUI:

Main Menu>General Postproc>Nodal Calcs>Sum @ Each Node

$he FORCEcommand "Main Menu>General Postproc>Options for Outp# dictates hich

component of the forces is bein% re&ieed:

' $otal "default#

' (tatic component' )ampin% component

' Inertia component

For a body in equilibrium, the total load "usin% all FORCEcomponents# is zero at all nodes

except here an applied load or reaction load exists.

!!"!# Option$ %ine Element Results

!ommand"s#:

ET&'%E

GUI:

Main Menu>General Postproc>Element Ta(le>)efine Ta(le

For line elements, such as beams, spars, and pipes, use this option to %ain access to deri&ed data"stresses, strains, etc.#. *esults data are identified by a combination of a label and a sequence

number or component name on the ET&'%Ecommand. (ee (ection +..-, !reatin% an

/lement $able, in theANSYS Basic Analysis Procedures Guidefor details.

!!"!*+ Option$ Print Error Estimation

!ommand"s#:

PRERR

GUI:

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Main Menu>General Postproc>List Results>Percent Error

For linear static analyses using solid or shell elements, use the PRERRcommand to list theestimated solution error due to mesh discretization. This command calculates and lists thepercent error in structural energy norm (SEPC), which represents the error relative to a

particular mesh discretization.

5.5.4.11 Option: Display Contour of Error Estimation

Command(s)

PLEOL,SE!!

"#$

Main Menu>General Postproc>Plot Results>!Contour Plot!Element olu

#se PLEOL,SE!! to contour the element%&y%elementstructural energy error(SE!!).

!egions o' high SE!! on the contour display are good candidates 'or mesh re'inement. SeeSection .., "Estimating Solution Error,* in theANSYS Basic Analysis Procedures Guide'or

more details a&out error estimation.

5.5.4.1" Option: Contour Displays

Command(s)

PL#OLor PLEOL

"#$

Main Menu>General Postproc>Plot Results>!Contour Plot!#o$al olu or Element olu

#se these options to contour almost any result item, such as stresses (S+, S, S-...), strains

(EPE+, EPE, EPE-...), and displacements (#+, #, #-...).

TheKUND'ield on PL#OLand PLEOLgives you the option o' overlaying the

unde'ormed shape on the display.

ou can also contour element ta&le data and line element data

Command(s)

PLE%&', PLL

"#$

Main Menu>General Postproc>Element %a(le>Plot Element %a(le

Main Menu>General Postproc>Plot Results>!Contour Plot!Line Elem Res

Caution:/erived data, such as stresses and strains, are averaged at the nodes &y the PL#OLcommand. This averaging results in *smeared* values at nodes where elements o' di''erent materials,

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different shell thicknesses, or other discontinuities meet. To avoid the smearing effect, use selecting(described in Chapter 7of theANSYS Basic Analysis Procedures Guide) to select elements of the

same material, same shell thickness, etc. before issuing PLNSOL. Alternatively, use Poer!raphicsith the AVREScommand (Main Menu>General Postproc>Options for Outp) to not average

results across different materials and"or different shell thicknesses.

5.5.4.13 Option Vector !ispla"s

Command(s)#

PLVE#$(vector displays), PRVE#$(vector listings)

!$%#

Main Menu>General Postproc>Plot Results>%Vector Plot%Pre&efine&

Main Menu>General Postproc>List Results>Vector !ata

&ector displays (not to be confused ith vector mode) are an effective ay of vieing vector

'uantities, such as displacement (%P), rotation (*+T), and principal stresses (, -, ).

5.5.4.14 Option $a'ular Listin(s

Command(s)#

PRNSOL(nodal results)

PRESOL(element/by/element results)

PRRSOL(reaction data), etc.

NSOR$, ESOR$

!$%#

Main Menu>General Postproc>List Results>solution option

Main Menu>General Postproc>List Results>%Sorte& Listtin(%Sort No&es or Sort Ele)s

$se the NSOR$and ESOR$commands to sort the data before listing them.

5.5.4.15 Ot*er #apa'ilities

0any other postprocessing functions/mapping results onto a path, load case combinations, etc./are

available in P+T. ee Chapter 1of theANSYS Basic Analysis Procedures Guidefor details.

5.5.5 Sa)ple +nput

A sample input listing for a full transient analysis is shon belo#

! Build the Model

/FILNAM,... ! Jobname

/TITLE,... ! Title

/PREP7 ! Enter PREP7

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--- ! Generate model

---

FINISH

! Apply Loads and Obtain the Solution

/SOLU ! Enter SOLUION

AN"E#$ANS ! ransient analysis

$NO"#FULL ! Full method

%#&&& ! 'onstraintsF#&&& ! Loads

SF#&&&

AL"HA%#&&& ! (ass dampin)

*EA%#&&& ! Sti++ness dampin)

,*'#&&& ! $amped or stepped loads

I(E#&&& ! ime at end o+ load step

AUOS#ON ! Auto time steppin)

%ELI(#&&& ! ime step sie

OU$ES#&&& ! $esults +ile data options

LS.$IE ! .rite +irst load step

---

--- ! Loads# time# et& +or 0nd load step

---

LS.$IE ! .rite 0nd load stepSA1E

LSSOL1E#2#0 ! Initiate multiple load step solution

FINISH

!

! $e3ie4 the $esults

/"OS05

SOLU#&&& ! Store solution summary data

NSOL#&&& ! Store nodal result as a 3ariable

ESOL#### ! Store element result as a 3ariable

$FO$'E#&&& ! Store reation as a 3ariable

"L1A$#&&& ! "lot 3ariables

"$1A$#&&& ! List 3ariables

FINISH

/"OS2

SE#&&& ! $ead desired set o+ results into database

"L%IS"#&&& ! %e+ormed shape

"$$SOL#&&& ! $eation loads

"LNSOL#&&& ! 'ontour plot o+ nodal results

"$E$$ ! Global perent error 6a measure o+ mesh ade7uay8

---

--- ! Other postproessin) as desired

---

FINISH

See theANSYS Commands Reference for a discussion of the ANTYPE, TRNOPT, ALPHAD,

BETAD, KBC, TIME, AUTOTS, DELTIM, OUTRES, LSWRITE, LSSOLVE, SOLU, NSOL,

ESOL, RFORCE, PLVAR, PRVAR, PLDISP, PRRSOL, PLNSOLand PRERRcommands.

5.6 Reduced Tra!"e# D$a%"c Aa&$!"!

The reduced method, as its name implies, uses reducedmatrices to calculate the dynamic response. Itis available in the ANSYS/Multiphysics, ANSYS/Mechanical, and ANSYS/Structural products. You

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should consider using this method if you don't want to include nonlinearities (other than simple node-to-node contact) in the analysis.

The procedure for a reduced transient dynamic analysis consists of five main steps:

1. Build the model.

2. !tain the reduced solution.

". #eview the results of the reduced solution.

$. %&pand the solution (e&pansion pass).

. #eview the results of the e&panded solution.

f these the first step is the same as for the full method e&cept that no nonlinearities are allowed

(other than simple node-to-node contact which is specified in the form of agap conditioninstead of

an element type). etails of the other steps are e&plained !elow.

5.6.1 Obtain the Reduced Solution

By reduced solution we mean the degree of freedom solution calculated at the master *. The tas+s

re,uired to o!tain the reduced solution are as follows:

1. %nter /T0.

ommand(s):

/SOLU

3/0:

Main Menu>Solution

2. efine the analysis type and analysis options. These are the same as descri!ed for the full method

e&cept for the following differences:

4 hoose the reducedmethod of solution 5TRNOPT6.

4 onlinear options 5NLGEOM SSTI NROPT6 are not availa!le.

4 7ou may include prestress effects 5PSTRES6. This re,uires element files from a previous static(or transient) analysis8 see ection .119restressed Transient ynamic ;nalysis9 for details.

4 #estarts are not availa!le 5!NT"PE6.

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M

MGEN

TOTAL

MLIST

MDELE

3/0:

Main Menu>Solution>Master DOFs>Define/Copy/Progra Sele!te"

Main Menu>Solution>Master DOF>List All

Main Menu>Solution>Master DOFs>Delete

$. efine gap conditions if any.

ommand(s):

GP

3/0:

Main Menu>Solution>Dynai! Gap Con">Define

7ou can also list the defined gaps and delete gaps.

ommand(s):

GPLIST

GPDELE

3/0:

Main Menu>Solutions>Dynai! Gap Con">List All

Main Menu>Solutions>Dynai! Gap Con">Delete

Gap Con"itions

3ap conditions can only !e defined !etween two master nodes or !etween master nodes andground as shown in the following figure.

Figure #$% E&aples of gap !on"itions

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Gap conditions are similar to gap elements and are specified between surfaces that are expectedto contact (impact) each other during the transient. The ANSYS program accounts for the gap

force, which deelops when the gap closes, b! using an e"uialent nodal load ector.

Some guidelines to define gap conditions are presented below#

$ %se enough gap conditions to obtain a smooth contact stress distribution between the contacting

surfaces.$ &efine a reasonable gap stiffness. 'f the stiffness is too low, the contacting surfaces ma!

oerlap too much. 'f the stiffness is too high, a er! small time step will be re"uired duringimpact. A general recommendation is to specif! a gap stiffness that is one or two orders of

magnitude higher than the adacent element stiffness. You can estimate the adacent element

stiffness using A*+, where A is the contributing area around the gap condition, is the elasticmodulus of the softer material at the interface, and + is the depth of the first la!er of elements at

the interface.

. Appl! initial conditions to the model. The following loading restrictions appl! in a reduced

transient d!namic anal!sis#

$ -nl! displacements, forces, and translational accelerations (such as grait!) are alid.

Acceleration loading is not allowed if the model contains an! master &- at an! nodes withrotated nodal coordinate s!stems.

$ orces and non/0ero displacements must be applied onl! at master &-.

As mentioned for the full method, multiple load steps are usuall! re"uired to specif! the load

histor! in a transient anal!sis. The first load step is used to establish initial conditions, and

second and subse"uent load steps are used for the transient loading, as explained next.

$ stablish initial conditions. The onl! initial condition that ma! be explicitl! established is the

initial displacement ( )1 that is, initial elocit! and acceleration must be 0ero ( 2 3, 2 3).&isplacements cannot be deleted in subse"uent load steps, therefore the! cannot be used to

specif! an initial elocit!. 'n a reduced transient anal!sis, a static solution is alwa!s performed

as the first solution, using the loads gien, to determine .$ Specif! load step options for the first load step. The following options are aailable for the first

load step.

Table 5-5 Options for the first load step

Option Command GUI Path

Dynamics Options

Transient 'ntegration4arameters

TINTPMain Menu!olution-"oad !tep Opts-

Time#$re%uencTime Inte&ration

&amping '"P('D

)*T'D

MP+

D'MP

Main Menu!olution-"oad !tep Opts-Time#$re%uenc

Dampin&

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General Options

Integration Time Step DELTIMMain Menu>Solution>-Load Step Opts-

Time/Frequenc>Time& Time Step

Output Control Options

Printed Output OT!"Main Menu>Solution>-Load Step Opts-Output

Ctrls>Solu !rintout

#$%$$ D'namics Options

Dynamic options include the following:

Transient Integration Parameters[TI(T!]

Transient integration parameters control the nature of the Newmar time integration techni!ue"The default is to use the constant a#erage acceleration scheme$ see theANSYS TheoryReference for further details"

Damping

Damping in some form is present in most structures and should %e included in your analysis"&ou can specify four forms of damping in a reduced transient dynamic analysis:

'lpha (mass) damping [)L!*)D]

*eta (stiffness) damping [+ET)D]

+aterial,dependent %eta damping [M!-D'+P] .lement damping (/O+*IN0- etc")

See Section 1"23"4- 5Damping-5 for further details"

#$%$$, General Options

6eneral options include the following:

Integration Time Step[DELTIM]

The integration time step is assumed to %e constant throughout the transient"

Note,If you do issue the TIMEcommand for the first load step- it will %e ignored" The first

solution is always a static solution at TI+. 7 8"

#$%$$ Output Control Options

Output control options include the following:

Printed Output[OT!"]

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Use this option to output the displacement solution at the master DOF.

6. Write the first load step to a load step file (Jobname.S01).

Command(s):

LSWRITE

U!:

Main Menu>Solution>-Solve-Write LS File

". Specif# loads and load step options for the transient loadin$ portion% &ritin$ each load step to aload step file 'LSWRITE.

he follo&in$ load step options are *alid for the transient load steps:

enera! Options

+ ime (specifies the time at the end of the load step) 'TIME+ Stepped 'KBC%1 or ramped loads 'KBC

Output "ontro!s

+ ,rinted output 'OUTPR+ -educed displacement file 'OUTRES

he onl# *alid lael on these commands is /SO (nodal solution). he default for OUTRESis

to &rite the solution for e*er# fourth timepoint to the reduced displacement file (unless there

are $ap conditions defined% in &hich case the default is to &rite e*er# solution).

2. Sa*e a ac3up cop# of the dataase to a named file.

Command(s):

SAVE

U!:

Utility Menu>File>Save a

4. Start the transient solution. For additional &a#s to create and sol*e multiple load steps (the arra#

parameter method and the multiple SOLVEmethod)% see Section 5.10.5of theANSYS #asic Ana!ysisProcedures uide.

Command(s):

LSSOLVE

U!:

Main Menu>Solution>-Solve-Fro! LS File

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10. Leave SOLUTION.

Command(s):

FINISH

GUI:

Close the Solution menu.

5.6.2 Step 3: Review the Results of the Reduced Solution

Results from the redued trans!ent d"nam! solut!on are #r!tten to the redued d!s$laement f!le%

Jobname.R&S'. The" ons!st of t!mevar"!n d!s$laements at the master &O*. +ou an rev!e# the

master &O* d!s$laements as a funt!on of t!me us!n 'OST,-. ('OST1 annot e used% eause theom$lete solut!on at all &O* !s not ava!lale.)

The $roedure to use 'OST,- !s the same as desr!ed for the full method% e/e$t for the follo#!n

d!fferenes:

efore def!n!n the 'OST,- var!ales% use the FILommand (!"in !enu#$imeHist

%ostp&o#Settin's#File) to s$e!f" that data are to e read from Jobname.R&S'. *or e/am$le%

!f the 2oname !s TR3NS% the FILommand #ould e: *IL4%TR3NS%R&S'. (" default%'OST,- loo5s for a results f!le% #h!h !s not#r!tten " a redued trans!ent solut!on.)

Onl" nodal deree of freedom data (at master &O*) are ava!lale for $roess!n% so "ou an use

onl" the NS(Lommand to def!ne var!ales.

5.6.3 )p"nd the Solution *)p"nsion %"ss+

The e/$ans!on $ass starts #!th the redued solut!on and alulates the om$lete d!s$laement% stress%and fore solut!on at all derees of freedom. These alulat!ons are done onl" at t!me$o!nts that "ous$e!f". efore "ou e!n the e/$ans!on $ass% therefore% "ou should rev!e# the results of the redued

solut!on (us!n 'OST,-) and !dent!f" the r!t!al t!me$o!nts.

Note3n e/$ans!on $ass !s not al#a"s re6u!red. *or !nstane% !f "ou are !nterested ma!nl" !n

d!s$laements at s$e!f! $o!nts on the struture% then the redued solut!on ould sat!sf" "ourre6u!rements. 7o#ever% !f "ou #ant to determ!ne d!s$laements at nonmaster &O*% or !f "ou are

!nterested !n the stress or fore solut!on% then "ou must $erform an e/$ans!on $ass.

5.6.3., %oints to Remem-e&

The .R&S'% .483T% .4S39% .&% and .TRI f!les from the redued solut!on must e ava!lale.

The dataase must onta!n the same model for #h!h the redued solut!on #as alulated.

The $roedure for the e/$ans!on $ass !s e/$la!ned elo#.

'ae , of ;;STRUCTUR3L: Cha$ter ;: Trans!ent &"nam! 3nal"s!s (U'1


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5.6.3.2 Expanding the Solution

1. Re-enter SOLUTION.

Command(s):

/SOLU

GUI:

Main Menu>Solution

Note$You must expl!tl" lea#e SOLUTION (usn$ t%e FINISH!ommand) and re-enter

(/SOLUION) &e'ore per'ormn$ t%e expanson pass.

. !t#ate t%e expanson pass and ts optons.

a!le 5"6 Expan#ion pa## option#

Option $o%%and &UI 'ath

*xpanson +assOn,O''

E(')SS Main Menu>Solution>")nal*#i# *pe"Expan#ion'a##

No. o' Solutons to &e*xpanded

NUME('Main Menu>Solution>"Load Step Opt#"

Expan#ion'a##>+ange o, Solu-#

Sn$le Soluton to*xpand

E('SOLMain Menu>Solution>"Load Step Opt#"Expan#ion'a##>

"Single Expand"* i%e/Fe0

5.6.3.3 Option1 Expan#ion 'a## On/O,, E(')SS

C%oose ON.

5.6.3.4 Option1 Nu%!e o, Solution# to !e Expanded NUME('

Spe!'" t%e num&er. T%s num&er o' e#enl" spa!ed solutons ll &e expanded o#er t%e spe!'ed tmeran$e. T%e solutons nearest t%ese tmes ll &e expanded. lso spe!'" %et%er to !al!ulate stresses

and 'or!es (de'ault s to !al!ulate &ot%).

5.6.3.5 Option1 Single Solution to Expand E('SOL

Use t%s opton to dent'" a sn$le soluton 'or expanson ' "ou dont need to expand multple

solutons n a ran$e. You !an spe!'" t et%er &" load step and su&step num&er or &" tme. lso

spe!'" %et%er to !al!ulate stresses and 'or!es (de'ault s to !al!ulate &ot%).

/. Spe!'" load step optons. T%e onl" optons #ald 'or a transent d"nam! expanson pass are output!ontrols:

+a$e /0 o' STRUCTURL: C%apter : Transent 2"nam! nal"ss (U+13340414)

1,,01%ttp:,,mostreal.s5,%tml,$ude6,$-str,GSTR.%tm


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5.6.3.6 Output Controls

Printed Output [OUTPR]

Use this option to include any results data on the output file (Jobname.OUT).

Database and Results File Output[OUTRES]

This option controls the data on the results file (Jobname.RST).

Extrapolation of Results [ERESX]

Use this option to review element interation point results !y copyin them to the nodes instead

of e"trapolatin them (default).

Note-The #R$% field on OUTPRand OUTREScan only !e &'' or O$. ERESXallows

you to review element interation point results !y copyin them to the nodes instead of

e"trapolatin them (default).

. Start e"pansion pass calculations.

*ommand(s)+

SOLVE

,U-+

Main Menu>Solution>-Solve-Current LS

. Repeat steps /0 10 and for additional solutions to !e e"panded. $ach e"pansion pass is stored as a

separate load step on the results file.

2. 'eave SO'UT-O.

*ommand(s)+

!"!S#

,U-+

Close t$e Solution %in&o%.

5.6.' Revie% t$e Results o( t$e E)pan&e& Solution

Results from the e"pansion pass are written to the structural results file0Jobname.RST. They consistof the followin data0 calculated at each time3point for which the reduced solution was e"panded+

4rimary data5 odal displacements (U60 U70 U80 ROT60 ROT70 ROT8)

9erived data+

5 odal and element stresses

4ae 1: of STRU*TUR&'+ *hapter + Transient 9ynamic &nalysis (U4:;;>mostreal.s?>html>uide@>3str>,STR.htm


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Nodal and element strains Element forces Nodal reaction forces etc.

You can review these results using POST1. (If ou e!"anded solutions at several time#"oints$ ou canalso use POST%& to o'tain gra"hs of stress versus time$ strain versus time$ etc. The "rocedure to use

POST1 (or POST%& is the same as descri'ed for the full method.

5.7 Sample Transient Dynamic Analysis (GUI

Method)

In this e!am"le$ ou will "erform a transient dnamic analsis using the reduced method to determinethe transient res"onse to a constant force with a finite rise in time. In this "ro'lem$ a steel 'eamsu""orting a concentrated mass is su')ected to a dnamic load.

5.7.1 Prolem Description

* steel 'eam of length +,(, and geometric "ro"erties shown in Pro'lem S"ecifications is su""ortinga concentrated mass$ m. The 'eam is su')ected to a dnamic load -(t with a rise time trand a

ma!imum value -1. If the weight of the 'eam is considered to 'e negligi'le$ determine the time of

ma!imum dis"lacement res"onse tma!and the res"onse ma!. *lso determine the ma!imum 'ending

stress 'endin the 'eam.

The 'eam is not used in this solution and its area is ar'itraril in"ut as unit. The final time of .1 secallows the mass to reach its largest deflection. One master degree of freedom is selected at the mass in

the lateral direction. * static solution is done at the first load ste". Smmetr could have 'een used inthis model. The time of ma!imum res"onse (./% sec is selected for the e!"ansion "ass calculation.

5.7.! Prolem Speci"ications

The following material "ro"erties are used for this "ro'lem0

E 2 ! 123si

m .%4/&5 3i"s#sec%6in

The following geometric "ro"erties are used for this "ro'lem0

l 7.& in8

h 17 in+,(, % ft %8 in.

9oading for this "ro'lem is0

-1 % 3i"s

tr .54 sec

Page 2% of 44ST:;446g#str6?ST:4.htm


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5.7.3 Problem Sketch

Figure 5-3 Model of a Steel Beam Supporting a Concentrated Mass

5.7.3. Specif! the "itle

1. Choose menu path #tilit! Menu$File$Change "itle.

2. Enter the text "Transient response to a constant force with a finite rise time."

3. Click on OK.

5.7.3.% &efine 'lement "!pes

1. Choose menu path Main Menu$Preprocessor$'lement "!pe$ (dd)'dit)&elete. The Element

Types dialo !ox appears.

2. Click on dd. The #i!rary of Element Types dialo !ox appears.

3. $n the left scroll !ox% click on "&tructural 'eam."

(. $n the riht scroll !ox% click on "2) elastic 3%" and click on pply.

*. $n the left scroll !ox% click on "&tructural +ass."

,. $n the riht scroll !ox% click on "3) mass 21%" and click on OK.

-. $n the Element Types dialo !ox% click once on "Type 2%" and click on Options.

. $n the scroll !ox for /otary inertia options% scroll to "20) wo rot iner" and select it.

. Click on OK and click on Close in the Element Types dialo !ox.

ae 33 of **&T/4CT4/#5 Chapter *5 Transient )ynamic nalysis 641718

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5.7.3.3 &efine *eal Constants

1. Choose menu path Main Menu$Preprocessor$*eal Constants. The Real Constants dialog boxappears.

2. Click on Add. The Element Type for Real Constant dialog box appears.

3. Click on !. The Real Constants for "EA#3dialog box appears.

$. Enter 1 for Area% &''.( for )**% and 1& for +eight.

,. Click on !.

(. )n the Real Constants dialog box% click on Add.

-. Click on Type 2 #A21and click on !. The Real Constants for #A21dialog box appears.

&. Enter .'2,/'(- in the 20 mass field and click on !.

/. Click on Close in the Real Constant dialog box.

5.7.3.+ &efine Material Properties

1. Choose menu path Main Menu$Preprocessor$Material Props$ -Constant-,sotropic. The)sotropic #aterial roperties dialog box appears.

2. Click on !. A second dialog box appears.

3. Enter 3'e3 for E 45oung6s modulus7 and click on !.

5.7.3.5 &efine odes

1. Choose menu path Main Menu$Preprocessor$-Modeling-Create$ odes$,n (ctie CS. TheCreate 8odes in Acti9e Coordinate ystem dialog box appears.

2. Enter 1 for node number and click on Apply to define node 1 at '%'%'.

3. Enter 3 for node number.

$. Enter 2$'%'%' for %5%* coordinates and click on !.

,. Choose menu path Main Menu$Preprocessor$-Modeling-Create$ odes$Fill bet/een ds.The :ill bet;een 8ds. menu appears.

(. Click once on nodes 1 and 3% and click on !. The Create 8odes "et;een 2 8odes dialog boxappears.

-. Click on ! to accept the default settings.

age 3$ of ,,TR Transient ynamic Analysis 4??mostreal.sk?html?guide@,,?g0str?TR,.htm


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5.7.3.6 Define Elements

1. Choose menu path Main Menu>Preprocessor>-Modeling-Create> Elements>-Auto Numered-

!"ru Nodes. The Elements from 8odes picking menu appears.

2. Click once on nodes 1 and 2% and click on Apply.

3. Click once on nodes 2 and 3% and click on !.

$. Choose menu path Main Menu>Preprocessor>-Modeling-Create> Elements>Elem Attriutes.The Element Attributes dialog box appears.

,. elect 2 for the #ass 21 Element type number.

(. elect 2 for Real constant set no. and click on !.

-. Choose menu path Main Menu>Preprocessor>-Modeling-Create> Elements>-Auto Numered-

!"ru Nodes. The Elements from 8odes picking menu appears.

&. Click once on node 2 and click !.

5.7.3.7 Define Anal#sis !#pe and Anal#sis $ptions

1. Choose menu path Main Menu>%olution>-Anal#sis !#pe-Ne& Anal#sis.

2. Click on BTransientB to select it% and click on !.

3. Choose menu path Main Menu>%olution>Anal#sis $ptions. The Transient Analysis dialog box

appears.

$. Click on BReducedB and click on !. The Reduced Transient Analysis dialog box appears.

,. )n the drop do;n menu for amping effects% select B)gnore.B

(. Click on !.

5.7.3.' Define Master Degrees of (reedom

1. Choose menu path Main Menu>%olution>Master D$(s>-)ser %elected-Define. The efine

#aster :s picking menu appears.

2. Click on node 2 and click on !. The efine #aster :s dialog box appears.

3. )n the drop do;n menu for 1st degree of freedom% select B??mostreal.sk?html?guide@,,?g0str?TR,.htm


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5.7.3.9 Set Load Step Options

1. Choose the menu path Main Menu>Solution>-Load Step Opts- Time/Frequenc>Time - Time

Step. The Time and Time Step Options dialog box appears.

2. Enter .004 for Time step size and clic on O!.

5.7.3.1 !ppl" Loads #or t$e First Load Step

1. Choose menu path Main Menu>Solution>-Loads-!ppl">-Structural- %isplacement>On

&odes. The "ppl# $%&OT on 'odes picing menu appears.

2. Clic on node 1% and clic on "ppl#. The "ppl# $%&OT on 'odes dialog box appears.

(. Clic on )$*) to select it and clic on "ppl#.

4. Clic on node (% and clic on O!. The "ppl# $%&OT on 'odes dialog box appears.

+. Clic on )$,) to select it. )$*) should remain selected. Clic on O!.

-. Choose menu path Main Menu>Solution>-Loads-!ppl">-Structural- Force/Moment>On&odes. The "ppl# / on 'odes picing menu appears.

. Clic on node 2 and clic on O!. The "ppl# / on 'odes dialog box appears.

. 3n the drop don menu for 5irection of force/mom% select )*.) 6ea7e the 7alue as blan 8zero9

for the initial static solution.

:. Clic on O!% and clic on S";ESolution>-Load Step Opts-Output 'trls>%(/)esults File. TheControls for 5atabase and &esults ile >riting dialog box appears.

2. Clic on the )E7er# substep) radio button and clic on O!.

5.7.3.1* Sol+e t$e First Load Step

1. Choose menu path Main Menu>Solution>-Sol+e-'urrent LS.

2. &e7ie the information in the status indo% and clic on Close.

(. Clic on O! on the Sol7e Current 6oad Step dialog box to begin the solution.

4. Clic on Close hen the solution is done indo appears.

?age (- of ++ST&$CT$&"6@ Chapter +@ Transient 5#namic "nal#sis 8$?1::019

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5.7.3.13 Apply Loads for the Next Load Step

1. Choose menu path Main Menu>Solution>-Load Step Opts- Tie!"re#uen$>Tie - Tie Step.The Time and Time Step Options dialog box appears.

2. Enter .075 for Time at end of load step and clic on O!.

". Choose menu path Main Menu>Solution>-Loads-Apply>-Stru$tural- "or$e!Moent>OnNodes. The #ppl$ %&' on (odes picing menu appears.

). Clic on node 2 and clic on O!. The #ppl$ %&' on (odes dialog box appears.

5. Enter 20 for %orce&moment *alue and clic on O!.

5.7.% Sol&e the Next Load Step

1. Choose menu path Main Menu>Solution>-Sol&e-'urrent LS.

2. +e*ie, the information in the status ,indo,- and clic on Close.

". Clic on O! on the Sol*e Current oad Step dialog box to begin the solution.

). Clic on Close ,hen the solution is done ,indo, appears

5.7.%.1 Set the Next Tie Step and Sol&e

1. Choose menu path Main Menu>Solution>-Load Step Opts- Tie!"re#uen$>Tie - Tie Step.

The Time and Time Step Options dialog box appears.

2. Enter .1 for Time at end of load step and clic on O!.

". Choose menu path Main Menu>Solution>-Sol&e-'urrent LS.

). +e*ie, the information in the status ,indo,- and clic on Close.

5. Clic on O! on the Sol*e Current oad Step dialog box to begin the solution.

/. Clic on Close ,hen the solution is done ,indo, appears.

7. Choose menu path Main Menu>"inish.

5.7.%.( )un the *xpansion +ass and Sol&e

1. Choose menu path Main Menu>Solution>-Analysis Type- *xpansion+ass. Set the Expansionpass radio button to On and clic on O!.

2. Choose menu path Main Menu>Solution>-Load Step Opts- *xpansion+ass>-Sin,le *xpand-y

Tie!"re#. The Expand Single Solution b$ Time&%reuenc$ dialog box appears.

". Enter 0.02 for Timepoint&%reuenc$ and clic on O!.

3age "7 of 55ST+4CT4+# Chapter 5 Transient 6$namic #nal$sis 431808189

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4. Choose menu path Main Menu>Solution>-Solve-Current LS.

5. Review the information in the status window, and click on Close.

6. Click on OK on the Solve Current Load Step dialo !o" to !ein the solution.

#. Click on Close when the solution is finished.

5.7.4.3 Review the Results in POST26

$. Choose menu path Main Menu>Tie!ist Post"ro>Settin#s>$ile. %he &ile Settins dialo !o"

appears.

'. (n the &iles scroll !o", scroll to and select )file.rdsp) and click on OK.

*. Choose menu pathMain Menu>Tie!ist Post"ro>%e&ine 'aria(les. %he +efined %ime-istor

/aria!les dialo !o" appears.

4. Click on 0dd. %he 0dd %ime-istor /aria!le dialo !o" appears.

5. Click on OK to accept the default of 1odal +O& result. %he +efine 1odal +ata dialo !o" appears.

6. 0ccept the default of ' for the reference num!er of the varia!le.

#. 2nter ' for node num!er.

3. 2nter 1SOL for userspecified la!el.

. (n the riht scroll !o", click on )%ranslation ) to select it.

$7. Click on OK, then click on Close in the +efined %ime-istor /aria!le dialo !o".

$$. Choose menu path Main Menu>Tie!ist Post"ro>)ra"h 'aria(les.

$'. 2nter ' for $st varia!le to raph and click on OK. %he raph appears on the 01SS 8raphics

window.

$*. Choose menu path Main Menu>Tie!ist Post"ro>List 'aria(les.

$4. 2nter ' for $st varia!le to list and click on OK.

$5. Review the information in the status window and click on Close.

5.7.4.4 Review the Results in POST*

$. Choose menu path Main Menu>)eneral Post"ro+>-Rea, Results-$irst Set.

'. Choose menu path Main Menu>)eneral Post"ro+>Plot Results>%e&ore, Sha"e. %he 9lot

+eformed Shape dialo !o" appears.

*. Click on )+ef : undeformed) and click on OK.

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5.7.4.5 Exit ANSYS

1. Choose QUIT from the ANSYS Toolbar.

2. Click on the save option yo !ant" an# click on $%.

5.8 A Sample Transient Dynamic Analysis(Command or Batc !etod"

Yo can perform the e&ample transient #ynamic analysis of a bracket sin' the ANSYS comman#s

sho!n belo! instea# of (UI choices. Items preface# !ith an e&clamation point )*+ are comments.

/PREP7

/TITLE, Transient Response to a Constant Force with a Finite Rise Time

ET,1,BEAM3 ! Twoimensiona" #eam

ET,$,MA%%$1,,,& ! Twoimensiona" mass

R,1,1,'(()*,1' ! Beam area + 1, I + '(()*, h + 1'R,$,)($-(*7 ! Mass

MP,E.,1,3(e3

,1

,3,$&(

FILL

E,1,$ ! Beam e"ements

E0E,$,1,1

TPE,$

REAL,$

E,$ ! T2pe $ e"ement with rea" constant $

M,$, ! Master 45F in irection at mi"e o6 #eam

FII%

/%5LATPE,TRA% ! Transient 2namic ana"2sis

TR5PT,RE4C,,54AMP ! Re8ce transient ana"2sis, i9nore ampin9

4ELTIM,)((& ! Inte9ration time step si:e

4,1,

4,3,.,,,,,

5TPR,BA%IC,1

5TRE%,ALL,1

F,$,F,( ! Force + ( at Time + (

%5L;E

TIME,)(7 ! Time at en o6 "oa step

F,$,F,$( ! Force is rampe to $(

%5L;E

TIME,)1 ! Constant 6orce 8nti" time + ()1%5L;E

FII%

/%5L

! The 6o""owin9 is the e


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NUMVAR,0

FILE,file,rdsp

NSOL,2,2,U,Y,NSOL ! Define the vriles

"LVAR,2 ! #rph the vriles

"RVAR,2 ! List the vriles

FINIS$

%"OS&'

SE&,FIRS& ! Red in res(lts"LDIS",' ! Displ) def*r+ed nd (ndef*r+ed shpe

FINIS$

5.9 Where to Find Other Examples

Several ANSYS publications, particularly theANSYS Verification Manual, describe additional

transient dynamic analyses.

TheANSYS Verification Manualconsists of test case analyses demonstrating the analysis capabilities

of the ANSYS program. While these test cases demonstrate solutions to realistic analysis problems,theANSYS Verification Manualdoes not present them as step-by-step examples ith lengthy data

input instructions and printouts. !oever, most ANSYS users ho have at least limited finite element

experience should be able to fill in the missing details by revieing each test case"s finite elementmodel and input data ith accompanying comments.

The folloing list shos you the variety of transient dynamic analysis test cases that theANSYSVerification Manual includes#

$%& 'arge 'ateral (eflection of )ne*ual Stiffness Springs

$%+ 'arge (eflection and otation of a eam /inned at 0ne 1nd

$%23 Transient esponse of a all 4mpacting a 5lexible Surface

$%67 Transient esponse of a Spring, %ass, (amping System

$%68 'ogarithmic (ecrement

$%69 5ree $ibration ith :oulomb (amping

$%6+ Transient esponse to an 4mpulsive 1xcitation

$%63 Transient esponse to a Step 1xcitation

$%66 Transient esponse to a :onstant 5orce ith a 5inite ise Time

$%6& Transient esponse of a i-'inear Spring Assembly

$%; /lastic esponse to a Suddenly Applied :onstant 5orce

$%;7 Transient esponse of a (rop :ontainer

$%;8 Simply Supported 'aminated /late )nder /ressure

/age + of 33ST):T)A'# :hapter 3# Transient (ynamic Analysis 88>873http#>>mostreal.s?>html>guide@33>g-str>ST3.htm


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VM84 Displacement Propagation along a Bar with Free Ends

VM85 Transient Displacements in a Suddenly Stopped Moing Bar

VM!" #arge $otation o% a Swinging Pendulum

VM"5& 'atural Fre(uency o% 'onlinear Spring)Mass System

VM"58 Motion o% a Bo**ing Buoy

VM"+! Dynamic Dou*le $otation o% a ,ointed Beam

VM"8- Transient $esponse o% a Spring)Mass System

5.10 Mode Superposition Transient Dynamic

Analysis

The mode superposition method sums %actored mode shapes .o*tained %rom a modal analysis/ to

calculate the dynamic response0 This method is aaila*le in the 1'S2S3Multiphysics1'S2S3Mechanical 1'S2S3Structural and 1'S2S3#inearPlus products0 The procedure to use the

method consists o% %ie main steps

"0 Build the model0

-0 6*tain the modal solution0

70 6*tain the mode superposition transient solution0

40 Epand the mode superposition solution0

50 $eiew the results0

6% these the %irst step is the same as descri*ed %or the %ull method0 The remaining steps are descri*ed*elow0

5.10.1 Obtain the Modal Solution

9hapter 7descri*es how to o*tain a modal solution0 2ou should :eep in mind the %ollowingadditional points

; The mode etraction method should *e either reduced Bloc: #anc"5http33mostreal0s:3html3guide?553g)str3@ST$50htm


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Specify displacement constraints, if any. These constraints will be ignored if they are specifiedin the mode superposition transient solution instead of in the modal solution.

If you need to apply element loads(pressures, temperatures, accelerations, etc.) in the transientdynamic analysis, you must specify them in the modal analysis. The loads are ignored for the

modal solution, but a load vector will be calculated and written to the mode shape file(Jobname.M!"). #ou can then use this load vector for the transient solution.

The modes need not be e$panded for the mode superposition solution. (If you want to review

mode shapes from a reduced modal solution, however, you must e$pand the mode shapes.) The model data (e.g., nodal rotations) should not be changed between the modal and transient

analyses.

5.10.2 Obtain the Mode Superposition Transient Solution

In this step, the program uses mode shapes e$tracted by the modal solution to calculate the transient

response.


The mode shape file (Jobname.M!") must be available.

The database must contain the same model for which the modal solution was obtained.

5.10.2.2 Obtaining the Solution

The procedure to obtain the mode superposition transient solution is described below%

&. "nter S'TI.

*ommand(s)%

/SOLU

+I%

Main MenuSolution

. !efine the analysis type and analysis options. These are the same as described for the full method,e$cept for the following differences%

*hoose the mode superposition method of solution -TR!OPT.

Specify the number of modes you want to use for the solution -TR!OPT. This determines the

accuracy of the transient solution. /t a minimum, you should use all modes that you thin0 willcontribute to the dynamic response. If you e$pect higher fre1uencies to be e$cited, for e$ample,

the number of modes specified should include the higher modes. The default is to use all modes

calculated in the modal solution. onlinear options -!L"#OM, SST$%, !ROPT are not available.

2estarts are not available -&!T'P#.

3. !efine gap conditions, if any. They can only be defined between two master nodes or between

master nodes and ground. More details about gap conditions are presented under the reduced method.

4age 5 of 66ST2*T2/'% *hapter 6% Transient !ynamic /nalysis (4&77898&8)

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Command(s):

GP

GUI:

Main Menu>Solution>Dynamic Gap Cond>Define

4. Apply loads to the model. The following loading restrictions apply in a mode superposition

transient dynamic analysis:

!nly forces" translational accelerations" and a load #ector created in the modal analysis are

#alid. Imposed non$%ero displacements are ignored. Use the LVSCALEcommand (Main

Menu>Solution>-Loads-Apply> Load Vector>For Mode Super) to apply the load #ectorfrom the modal solution.

If mode shapes from a reducedmodal solution are &eing used" forces may &e applied only at

master '!.

ultiple load steps are usually re*uired to specify the load history in a transient analysis. Thefirst load step is used to esta&lish initial conditions" and second and su&se*uent load steps are

used for the transient loading" as e+plained ne+t.

,sta&lish initial conditions. The only initial condition that may &e e+plicitly esta&lished is the

initial displacement. A static solution using the mode superposition method is always

performed as the first solution with the gi#en loads. If -ower'ynamics was used for the modalsolution" no loads or displacements are allowed (that is" only u/ is #alid as the initial

condition). or pseudo$static analyses" the mode superposition method may yield poor results at

TI,/.

The following load step options are a#aila&le for the first load step:

Tale !-" #ptions for t$e first load step

#ption Command G%& Pat$

Dynamics #ptions

Transient Integration-arameters

T&'TPMain Menu>Solution>-Load Step #pts-

Time(Fre)uenc>Time &nte*ration

0oad 1ector LVSCALEMain Menu>Solution>-Loads-Apply>Load Vector>For

Mode Super

'amping

ALP+AD

,ETAD

DMPAT

MP.

DAMP

Main Menu>Solution>-Load Step #pts-Time(Fre)uenc>

Dampin*

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General Options

Integration Time Step DELTIMMain Menu>Solution>-Load Step Opts-

Time/Frequenc>Time & Time Step

Output Control Options

Printed Output OT!"Main Menu>Solution>-Load Step Opts-Output

Ctrls>Solu !rintout

#$%$'$( D)namics Options

Dynamic options include the following:

Transient Integration Parameters[TI*T!]

Transient integration parameters control the nature of the Newmar time integration techni!ue"The default is to use the constant a#erage acceleration scheme$ see yourANSYS TheoryReferencefor further details"

Load Vector[L+SC,LE]

The load #ector option allows you to apply a load #ector created %y the modal solution as oneof the loads" &ou can use such a load #ector to apply element loads 'pressures( temperatures(

etc") on the model"

am!ing

Damping in some form is present in most structures and should %e included in your analysis"&ou can specify fi#e forms of damping in a mode superposition transient dynamic analysis:

*lpha 'mass) damping [,L!,D]

+eta 'stiffness) damping [.ET,D] ,onstant damping ratio [DM!",T]

-aterial.dependent %eta damping [M!(D*-P] -odal damping [MD,M!]

See Section /"01"2( 3Damping(3 later in this chapter for further details"

#$%$'$ General Options

4eneral options include the following:

Integration Time Ste![DELTIM]

The only #alid option for the first load step is the integration time step [DELTIM]( which is

assumed to %e constant throughout the transient" +y default( the integration time step is

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assumed to be 1/(20f), wherefis the highest frequency chosen for the solution. The DELTIM

command is valid only in the first load ste and is ignored in subsequent load stes.

Note"!f you do issue the TIMEcommand in the first load ste, it will be ignored. The firstsolution is always a static solution at T!"# $ 0.

5.10.2.5 Output Control Options

%utut control otions include the following&

' Printed #ut!utOUTPR

*se this otion to control rintout of the dislacement solution at the master +%.

-. rite the first load ste to a load ste file (Jobname.01) by issuing the LSWRITEcommand.

ommand(s)&

LSWRITE

*!&

Main Menu>Solution>Sol!eWrite LS "ile

. ecify loads and load ste otions for the transient loading ortion, writing each load ste to a

load ste file LSWRITE.

The following load ste otions are valid for the transient load stes&

5.10.2.# $eneral Options

eneral otions include the following&

' Time #!tionTIME

This otion secifies time at the end of the load ste.

' Load VectorL%SC&LE

The load vector otion allows you to aly a load vector created by the modal solution as one

of the loads.

' Ste!!ed or Ram!ed Loads'(C

This otion indicates whether to ram the load change over the load ste '(C or to ste3

aly the load change '(C,1. The default is ramed.

5.10.2.) Output Control Options

%utut control otions include the following&

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Printed Output[OUTPR]

Use this option to control printed output.

Database and Results File Output[OUTRES]

This option controls the data on the reduced displacement file.

The only valid label on these commands is NSOL (nodal solution. The default for OUTRESis

to !rite the solution for every fourth time"point to the reduced displacement file (unless there

are #ap conditions defined$ in !hich case the default is to !rite every solution.

%. &f you used either the subspace or the 'loc Lac)os option for the mo

transient dynamic analysis in ansys

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