finite element modeling of isolator
finite element modeling of isolator
(OP)
I'm performing a harmonic vibration analysis (FEA) on a structure. There is a component mounted to this structure via isolators. I have the specifications for the isolator, which includes a static load rating at a give deflection and a ratio of dynamic and static spring rates.
How can I use this information to model the isolators with finite elements?
Thanks.
How can I use this information to model the isolators with finite elements?
Thanks.





RE: finite element modeling of isolator
dynamic rate =static rate*ratio
so put the dynamic rate calculated above into your stiffness matrix, in the correct units
Cheers
Greg Locock
RE: finite element modeling of isolator
RE: finite element modeling of isolator
Rather than using a dashpot, you can enter "modal damping" into the FEA software
A typical value for an isolated system might be Q=5, which is equivalent to 10% damping.
Tom Irvine
www.vibrationdata.com
RE: finite element modeling of isolator
You can't put a damper into a conventional FE model.
The reason is that the standard formulation assumes that the damping is proportional to the stiffness or mass matrix (I can't remember which).
Tom's workaround is the usual solution, or else you export your undamped results to a program which can handle non proportional damping.
Cheers
Greg Locock
RE: finite element modeling of isolator
RE: finite element modeling of isolator
It's proportional to the stiffness for "stiffness-proportional damping", and proportional to the mass for "mass-proportional damping".
(sorry, I couldn't resist
Brad
RE: finite element modeling of isolator
Cheers
Greg Locock