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1、*STEADY STATE DYNAMICSSteady-state dynamic response based on harmonic excitation.This option is used to calculate the systems linearized steady-state response to harmonic excitation.Product: Abaqus/StandardType: History dataLevel: StepReferences: “Direct-solution steadystate dynamic analysis, ”Secti
2、on 6.3.4 of the Abaqus Analysis Users Manual “Mode-based st eady-s tate dynamic analysis,” Sec tion 6.3.8 of the Abaqus Analysis Users Manual “Subspace-based steady-state dynamic analysis, ”Section 6.3.9 of the Abaqus Analysis Users ManualOptional and mutually exclusive parameters (used only if thed
3、ynamic response is not based on modal superposition):DIRECTInclude this parameter to compute the steady-state harmonic response directly in terms of the physical degrees of freedom of the model. This usually makes the procedure significantly more expensive, but it can be used if model parameters dep
4、end on frequency, if the stiffness of the systemisunsymmetricandtheunsymmetrictermsareimportant,orifthe system contains discrete damping (such as dashpot elements).SUBSPACE PROJECTIONInclude this parameter to compute the steady-state harmonic response on thebasisofthesubspaceprojectionmethod.Inthisc
5、aseadirectsolution isobtainedforthemodelprojectedontotheeigenvectorsobtainedinthe preceding * FREQUENCY st ep. This is a cos t-effec tive approach to including consideration of unsymmetric stiffness and frequency-dependent model parameters. It is more expensive than the modal superposition method bu
6、t less expensive than the direct-solution method.Set SUBSPACE PROJECTION=ALL FREQUENCIES (default) if the projection of the dynamic equations onto the modal subspace is to be performed at each frequency requested on the data lines.Set SUBSPACE PROJECTION=CONSTANT if a single projection of the dynami
7、c equations onto the modal subspace is to be used for all frequencies requested on the data lines. The projection is performed using model properties evaluated at the center frequency determined on a logarithmic or linear scale depending on the value of the FREQUENCY SCALE parameter.Set SUBSPACE PRO
8、JECTION=EIGENFREQUENCY if the projections onto the modal subspace of the dynamic equations are to be performed at each eigenfrequency within the requested ranges and at the eigenfrequencies immediately outside these ranges. The projections are then interpolated at each frequency requested on the dat
9、a lines. The interpolation is done on a logarithmic or linear scale depending on the value of the FREQUENCY SCALE parameter.Set SUBSPACE PROJECTION=PROPERTY CHANGE to select how often subspace projections onto the modal subspace are performed based on material property changes as a function of frequ
10、ency. The interpolation is done on a logarithmic or linear scale depending on the value of the FREQUENCY SCALE parameter.Set SUBSPACE PROJECTION=RANGE if the projections onto the modal subspace of the dynamic equations are to be performed at the lower limit of each frequency range and at the upper l
11、imit of the last frequency range. The interpolation is done on a linear scale. This value can be used only with the SIM architecture.Optional parameters:DAMPING CHANGEThis parameter is relevant only for SUBSPACE PROJECTION=PROPERTY CHANGE.Set this parameter equal to the maximum relative change in da
12、mping material properties before a new projection is to be performed. The default value is 0.1.FREQUENCY SCALESet this parameter equal to LOGARITHMIC (default) or LINEAR to determine whether a logarithmic or linear scale is used for output. If the SUBSPACE PROJECTION parameter is included and is set
13、 equal to either EIGENFREQUENCY or PROPERTY CHANGE, the same scale will be used for the interpolation of the subspace projections.FRICTION DAMPINGThis parameter is relevant only if the DIRECT or the SUBSPACE PROJECTION parameter is included.Set FRICTION DAMPING=NO (default) or YES to ignore or to in
14、clude friction-induced damping effects at the slipping contact interface for which a velocity differential is imposed.INTERVALSet INTERVAL=EIGENFREQUENCY if the frequency ranges specified on each data line are to be subdivided using the systems eigenfrequencies. This option requires a preceding *FRE
15、QUENCY step and is the default if the DIRECT parameter is omitted.Set INTERVAL=RANGE if the frequency range specified on each data line is to be used directly. This option is the default if the DIRECT parameter is included.REAL ONLYThisparameterisrelevantonly iftheDIRECTortheSUBSPACEPROJECTION param
16、eter is included.Include this parameter if damping terms are to be ignored so that a real, rather than a complex, system matrix is factored. This option can reduce computationaltimesignificantlyfortheDIRECTprocedureand,toalesser extent, for the SUBSPACE PROJECTION procedure.STIFFNESS CHANGETh i s parame t er i s re l evant on ly for SUBSPACE PROJECTION=PROPERTY CHANGE.Set this parameter equal to the maximum rela
