Nastran calculation questions: Dynamic release (???)

[caelywh]

Dear All,
I am using nastran to calculate the stress in a structure under g-force. I am new in this area. Someone told me that
I should apply "dynamic release" (maybe I did not get the
term right) to the constraints.

One example is a structure connecting to the vehicle frame.
I was told that I should apply this kind of operation to
the connection between the structure and frame.

Can anyone educate me about this?

Thanks a lot!

H.W.