A prestressed transient dynamic analysis calculates the dynamic response of a prestressed structure, such as a heat-treated part with residual thermal stresses. Prestressed-analysis procedures vary, depending on the type of transient dynamic analysis being performed.
You can include prestressing effects in a full transient dynamic analysis by applying the prestressing loads in a preliminary static load step. (Do not remove these loads in subsequent load steps.) The procedure consists of two steps:
Build your model, enter SOLUTION, and define a transient analysis type (ANTYPE,TRANS).
If prestressing effects develop because of nonlinear behavior (as in the case of residual thermal stresses in a casting), several load steps might be required to complete the static prestressing phase of your analysis. In the case of geometric nonlinearities (large deformation effects), you can capture the prestressing effect by issuing NLGEOM,ON.
For all subsequent load steps, turn time-integration effects on (TIMINT,ON), and proceed using the full transient dynamic analysis procedures described previously. Once all load steps are written to files (LSWRITE), you can initiate the multiple load step solution (LSSOLVE).
Note: If you intend to define initial conditions (IC), perform the static prestress solution as a separate solution. To activate the gyroscopic damping matrix in a prestressed transient analysis, perform a separate static solution with Coriolis effects activated (CORIOLIS,ON,,,ON) in a stationary reference frame.
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The IC command is valid only in the first load step.
In order to include prestress effects in a mode-superposition analysis, you must first do a prestressed modal analysis. See Modal Analysis for details. Once prestressed modal analysis results are available, proceed as for any other mode-superposition analysis.