April 1, 2020 at 4:41 pm
Wenlong
Ansys Employee

Hi,


1. You can define the frequency range to be maybe 29~31Hz, then you can find the response at 30Hz.


2. Nonlinearity can be introduced by nonlinear material (softening or cracking or plasticity, etc.), contact (frictionless or frictional contact, etc.), large deformation, and so on. 


Regards,


Wenlong