Mass Model (LUMPED/CONSISTENT) - CAESAR II - Help

CAESAR II Users Guide

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English
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CAESAR II
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CAESAR II Version
13

(Available for: Modal, Harmonic, Spectrum, and Time History)

Specifies a mass model type. Select CONSISTENT or LUMPED.

A lumped mass model makes very coarse simplifications that often result in correspondingly coarse results. The benefit is that it does not require a lot of memory for data storage.

The consistent mass model is well documented. Most texts on the subject, such as Structural Dynamics - Theory and Computation by Mario Paz, describe how to build the mass matrix. The consistent mass matrix takes into consideration the effects of bending and other rotational effects of the beam on its mass distribution, gives a more realistic result, but requires much more data storage.

  • If mass is added at a degree of freedom, CAESAR II assumes that it is a concentrated mass, and puts it on the on-diagonal term, effectively treating it as a lumped mass.

  • If mass is zeroed at a degree of freedom, CAESAR II assumes that you want to eliminate consideration of that DOF and zero out all elements on that row/column.