Discussion Forum

hello,

I'm doing my Diploma thesis on vibrating structures for Energy Harvesting. Actually, I'm trying to simulate the structures in Comsol, but i face several problems that i cannot solve without help :)

First of all, I am trying to simulate a clamped-clamped cantilever (let's say 750 um length and 60 um width) which is made of different thin layers (all in all 845 nm thick) and has the PDE of motion as following:

kl*u+kn*u^2+c*du/dt +m*d^2u/dt^2=F*sin(w*t)

So this is the so called Duffing oscillator, but I have no clue how to proceed with this nonlinear problem in Comsol. I know that i cannot use the frequency response because it's just for linear problems (at least this is what the support told me). I am also not sure, which application modes fit best for this problem. Actually I'm using the piezo solid application mode, because there is also a piezo layer included in my cantilever.
I have tried the transient analysis, but i do not reach sufficient convergence, especially near the eigenfrequency.

I really hope that someone can help me, because i'm almost desperate :) Maybe someone who has already experience with nonlinear vibrations?

Best regards,

Benedikt