Discussion Forum

My model consist of a plate, PZT 5A as piezopatch attached to plate surface, output resistace between the electrodes of PZT and point force applied to certain location to plate surface. Model has point force as harmonic input. I am trying to use model solver to get the voltage frequency response on resistive load.

I can simulate my model with Frequency Domain study without any problem. But I am facing problem when I want to use model solver as it uses Eigenfrequency analyses first and then Step 2: Frequency Domain, Modal analysis. When I set my output resistance (between piezo electrodes) to certain value like 10k ohm I am having extra imaginary modes and my real eigenfrequencies become complex due to coupling. Since Model Solver in *Frequency Domain, Modal * uses eigenvalue information from Eigenfrequency analyses, the response having unexpected modes due to the output resistance .

I was thinking that I can solve this issue with model configuration since comsol allow me to configure my model for Eigenfrequency and Frequency Domain, Modal steps separetly. So I use very low resistance value like 1 ohm for Eigenfrequency analyses and 10k ohm for Frequency Domain, Modal analyses. It seems that Frequency Domain, Modal analyses does not recognise 10k ohm resistance and it gives result as if it was 1 ohm. Is this a bug from COMSOL side or is there any other point that I am missing.

Thank you