Damping simulation

[greyspace1]

I have a whole vehicle chassis model (wheels,links, subframes etc) currently the bushes are linear and performing small displacement/strain, modal transient analyses in NASTRAN, with modal damping. I need to introduce better damping of the subframe hydramounts. The only data I have from the manufacturer is a curve of dynamic stiffness and loss angle at 3 different levels of rig displacement (.1, .5, 1mm) against frequency (1-60Hz).

I have a number of tire contact patch events to evaluate the transfer function from the TCP to the body. I have currently selected damping based on subframe frequency and velocity. Problem is that velocity changes for every event.

Can anyone tell me the alternative methods of introducing damping within a modal transient analysis.

All ideas / suggestion appreciated.

Thanks

 

[GregLocock]

You need to get out of NASTRAN and into a program that is not modally based. I think that PiUS PiRATE and Motran are the sort of program that we use to do what you are after - I am pretty sure they are proprietary programs.

A non linear FE package /may/ work for you, but I have no experience with them.

The other option would be to export your structures as flex models and then do the whole job in ADAMS.







Cheers

Greg Locock