Frequency Domain

[Eser]

Hi All!

I wanna solve a simple cantilever-beam problem using a mode-based steady state dynamic analyses in Abaqus. I have a force at the end of the beam F=sin(freq). I want to make a verification with the theoretical model. We know the maximum displacement as Ymax=F*l^3/(3EI) using the theoretical calculations.
I have the results from Abaqus already for the selected frequencies of number 200 between 0-20000Hz. In the results we have displacements solved for each frequency. If we put the equation F=sin(freq) in the theoretical equation Ymax=F*l^3/(3EI) we dont have the correct result comparing with the theoretical results although the beam model is already verified by a static analyses. So I think we need to transfer the function using inverse fourier transformation to time domain and then will be the results correct?
I am a little bit confused so did someone know how to interpret and compare the result of a mode-based steady state dynamic analyses of a simple cantilever beam with the theoretical result?

Thanks in advance,

Eser

 

[EricZhao]

I thought you might confusing between static analysis and dynamic analysis. The Ymax=F*l^3/(3EI) is only valid for static case, which means a constant load is applied very slowly to the structure.

I think you are using Abaqus to take a frequency spectrum (sweep sine) analysis. The results would be a curve with some peak at some frequency point. These peaks are the resonance frequencies of your beam. The frequency spectrum has nothing to do with Ymax=F*l^3/(3EI).