ansys 1

Hi,
you are right, there are 5 types of damping. But ALPHA and BETHA belongs to one type of damping, i.e Rayleigh damping. One that you don't name is constant damping (DMPRAT). They could (must not) be used in the following analyses:

Rayleigh : damped modal, harmonic, trancient, spectrum,
substudture
Material : damped modal, harmonic, trancient, spectrum
excluding PSD, substructure
Modal : harmonic, trancient with mode superposition,
spectrum
Element : damped modal, full & reduced harmonic, full &
reduced trancient, substucture
constant : harmonic, spectrum, trancient with mode
superposition

May be someone has successfully implemented damping in analysis not mentioned above, so please correct it.

cheers

thanks for the above information zuardy.

what values should be associated with the following damping types and how to get these values. Can u suggest me any book or any other source which can give me information?

regards,
visitor123

Hi visitor123,
let § be damping factor and f be eigenfrequency, then
Rayleigh factor are :
BETHA = (1/PHI)* (f1*§1 - f2*§2) / (f1^2 - f2^2)
ALPHA = 4*PHI*f1*(§1-PHI*BETHA*f1)
You can yield the damping factor from literatur or from experiment, e.g for steel § = 0.001

Constant damping :
BETHA = § / PHI * f

Material damping can be yielded from hysteric damping diagram, that gives us the dissipation energy per cyclic.

You can study the ANSYS help for futhure information

cheers