Learning Forum

[jojimat33]

I am trying to perform a shock analysis with preload on a system with non linear spring stiffness. As it is computationally expensive to solve non linear transient, is there any way to do a linear perturbation shock analysis, where prestress effects are included in the stiffness matrix.

[peteroznewman]

In Workbench bring out a Static Structural analysis block to apply the preload. Turn on Large Deflection.

Drag out a Modal analysis and drop it on the Solution cell of Static Structural. That feeds the prestressed stiffness matrix into the Modal analysis. Configure the Modal with a sufficient number of modes to capture at least 80% of the mass participation in each direction.

Drag out a Response Spectrum analysis and drop it on the Solution cell of Modal. Convert the shock acceleration-time data into a Shock Response Spectrum (SRS) to use as a load in the Response Spectrum analysis.

After you have solved all three systems, the results in the Response Spectrum analysis represent the peak stress, deformation, acceleration, etc that is predicted over the duration of the shock. This method is computationally efficient compared with solving the non-linear transient solution.