Simulation > Creo Simulate > Reference Links > Account for Stiffness
Account for Stiffness
By default, when you specify a preload for a fastener, the preload value is the load that the fastener applies on the undeformed geometry of the model. When the model deforms, the compressive force of the fastener on the structure relaxes. Hence, the resulting preload is substantially lower than the specified value and is reported as the fastenerName_axial_force measure in the summary rpt file for a static analysis.
Alternatively, you can have Creo Simulate use the actual preload that you specified for the fastener. To do so, select the Account for Stiffness check box on the Fastener Definition dialog box and run a static analysis, and the following steps are executed:
A base analysis runs with only the specified preload and the constraints in the model. External loads are not applied in this analysis. All the other model entities are preserved.
For each fastener with the Account for Stiffness check box selected, the resulting preload from the base analysis is recorded in the summary rpt file as fastenerName_axial_force.
A second analysis runs with all the external loads and constraints and using the new scaled preloads. At the end of the second analysis the value of the fastenerName_axial_force measure will be close to the specified preload value.
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In the above steps it is assumed that the conditions in the vicinity of the fasteners are linear and that the tightening of one fastener does not affect the stress field of another.