Composite Modal Damping
Composite modal damping allows the definition of the damping as a material
property. Material damping ratio MDAMP
is defined in the Properties tab
of the Material dialog box. The
program uses this property to calculate equivalent modal damping ratio
for each mode.
The composite modal damping is defined in terms of equivalent modal
damping ratios as:

where:
bj =
equivalent modal damping ratio of the jth
mode
{f}jT
= jth
normalized modal eigenvector
[M]
= modified global mass matrix constructed from the product of the element's
damping coefficient and its mass matrix.
If you specify material damping ratio MDAMP to be m for all materials in the
model, the equivalent modal damping ratio will be m for all modes.
For a list of viscous damping ratios for different materials click here.
Related topics
Global
Damping