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Rigid motion suppression [and eigenfrequency analysis] issue
Posted Dec 2, 2021, 2:04 p.m. EST Low-Frequency Electromagnetics, Structural & Acoustics, Structural Mechanics Version 5.6 0 Replies
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Hi,
I have a 3D model with materials of different CTEs stacked together and I'm analyzing the thermal expansion of some metal structures inside them over a range of temperatures.
From the blog below - I see that the Rigid motion suppression domain constraint is a better one to use - than a 'fixed' constraint' : https://www.comsol.com/blogs/how-to-provide-structural-stability-in-thermal-expansion-simulations/ . My model structure is similar to this - though in 3D and having many stacked layers.
To choose the domains on which to set the 'Rigid motion', I ran a quick eigenfrequency analysis [with a coarse mesh and the bottom-most surface 'fixed'] as suggested - but that didn't yield any eigenfrequencies close to 0. In fact they all were in the order of E7.
In the end, I had to manually pick a couple of the domains to run this through - but the run times were pretty huge [6.5hrs] - compared to a run [with the exact same model] that had a 'fixed' constraint on the bottom surface [1hr] .
I'm still new to COMSOL - and my model only involves a Solid-mechanical + electrostatics multiphysics, so any pointers on what to check for would be good - particularly the eigenfrequency analysis. I looked through the forum for anything similar posted on eigenfrequency - but couldn't find any.
Thanks Anand
Hello Anand Chandrashekar
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