Structural Dynamics

Structural Dynamics

In a random-vibration (PSD) analysis, why do one-sigma displacements change when element results are requested? Requesting element results should not affect the calculated displacements.

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      This behavior can occur if the model contains material-dependent damping, which is only used when element results are requested. Material-dependent damping is proportioned to the different materials based on the element strain energy. Thus, an analysis with element results requested can be more-heavily damped and calculate smaller displacements.