Modal analysis (impact hammer test) ABAQUS simulation

[yikyeh]

Hi,

Currently I am doing an experimental modal analysis (free-free boundary condition) using impact hammer. The test specimen is a mild steel plate. I have force-time graph from force transducer, acceleration-time graph from accelerometer and frequency response function (|Acceleration/Force| vs Frequency).

So now I want to do a free-free modal analysis simulation in ABAQUS. I am new to ABAQUS. So I dont know which analysis step should I use. Modal dynamics, steady-state dynamics or dynamics explicit? My main objective is to input hammer force time-history into abaqus, obtain acceleration-time graph and finally plot frequency response function (|Acceleration/Force| vs Frequency).


Is anyone has experience on this? It would be helpful if anyone has any suggestion. Thanks.

 

[Mustaine3]

With that load you have to work in time domain. In A/Standard it means *Modal Dynamic if you assume linear behavior or *Dynamic if it can be nonlinear.
Or you use A/Explicit with *Dynamic, Explicit.

Your results will also be in time domain.

 

[yikyeh]

Thanks for your reply.

If I use Modal Dynamics, with the acceleration-time graph that I obtain, how to plot frequency response function (|Acceleration/Force| vs Frequency)for all the modes in the frequency range of interest in ABAQUS? I'm gonna obtain a FRF graph like the image attached below. Anyone know how to do that?

Thanks.

 

[Mustaine3]

Make a FFT.

https://en.wikipedia.org/wiki/Fast_Fourier_transform