Damping |
 
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Damping |
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Flexcom presents a range of options to apply structural damping to the finite element model. This section briefly outlines the background theory for structural damping.
The structure damping matrix C, which multiplies the vector of structure velocity on the left hand side of the equations of motion, is defined by:
where:
•K is the structure stiffness matrix (this includes contributions from both structural stiffness and geometric stiffness)
•M is the structure mass matrix
•λ is the stiffness proportional damping coefficient
•μ is the mass proportional damping coefficient
A small level of damping is beneficial in many dynamic analyses in dissipating the effects of transients and high frequency noise. However, what particular values of l and m represent a small level of damping is very much dependent on the structure under consideration. For this reason, and because it is obviously important to quantify the effect particular values are having on the response in a particular run, it would in general be recommended that you perform a dynamic analysis with no damping, either initially or as a check.
Further information on this topic is contained in the following sections:
•Damping Coefficients describes stiffness and mass proportional damping coefficients.
•Damping Ratio describes coefficients defined as a function of a damping ratio and period.
•Deformation Mode Damping describes deformation mode specific damping.
•Damping Formulation explains the formulation options, updated and constant.
•*DAMPING is used to incorporate damping into a dynamic analysis.
•*DAMPING FORMULATION is used to specify the damping formulation to be used in a time domain dynamic analysis.
•*DAMPING RATIO is used to specify stiffness damping coefficients as a function of a damping ratio and a damping period.
