Note: This discussion is about an older version of the COMSOL Multiphysics® software. The information provided may be out of date.
Discussion Closed This discussion was created more than 6 months ago and has been closed. To start a new discussion with a link back to this one, click here.
Frequency Domain Calculation regarding a thin steel plate with piezos
Posted 15 gen 2013, 11:08 GMT-5 Studies & Solvers, Structural Mechanics Version 4.2a 3 Replies
Please login with a confirmed email address before reporting spam
I did some eigenfrequency simulations regarding a thin steel plate with two piezos attached. (PiezoA and PiezoDUT)
I placed the piezos at the maximums of a mode shape at about 122Hz.
For the eigenfrequency calculations I did a parameter sweep with respect to the thickness of PiezoDUT. The other one, PiezoA has a thickness of 0.5mm for every simulation.
So, what I got are the eigenfrequencies of the structure for the different thicknesses of PiezoDUT.
I think the results from the eigenfrequency calculation are correct, aren't they?
In the next step I want to do a frequency domain calculation where I want to excite PiezoA with a voltage with the calculated eigenfrequency of the structure in respect of the thickness of PiezoDUT. The voltage at PiezoDUT is what i want to calculate.
The problem i got here: When I excite the PiezoA with the eigenfrequency of the structure i got the following error:
----------------------------------------------------------------------------------------------
Failed to find a solution.
The relative residual (0.0028) is greater than the relative tolerance.
Returned solution is not converged.
----------------------------------------------------------------------------------------------
Please, could somebody help me with this problem?
Kind regards,
Christoph
Attachments:
Please login with a confirmed email address before reporting spam
Use free triangular mesh to mesh boundaries 4, 8, 14 first,
then use Swept mesh with three elements through the thickness.
Click Solve button. Converged solution is obtained with 2 steps.
Regards,
Sergei
Attachments:
Please login with a confirmed email address before reporting spam
thanks a lot for your help with the mesh. Creating more than one mesh element through the thickness would be much better.
Meanwhile I found out that in the frequency domain no damping of the system is considered.
Don't I have to add some damping to the system too, to calculate solutions for excitations at the eigenfrequencies?
Best regards,
Christoph
Please login with a confirmed email address before reporting spam
To add piezoelectric damping, right-click Piezoelectric Material Model node and select Damping and Loss.
To add damping to elastic material, right-click Linear Elastic Material node and select Damping.
You can specify damping in terms of Rayleigh damping or Loss factor. It is always difficult to decide what specific value for damping to choose. This topic was discussed in the forum extensively – try “damping” search.
Regards,
Sergei