Inconsistent results between full 3D (360 deg.) and one-quadrant (90 deg.) models in dynamic 3D

The model is a circular flat-panel with rubber surround. The panel is driven by a force through a former. This is effectively modelling part of a speaker.

The driving force of one-quadrant model is scaled proportionally. Displacement in z is nearly five times that of the full 3D model. Is there anything wrong in the models?

Thank you.
liml
liml
Panel Surround 90deg.liml
1M
liml
liml
Panel Surround 360deg.liml
1008K
picture4.png
1497 x 1002 - 93K
picture5.png
1643 x 1002 - 78K

Comments

  • Two reasons:

    1) The thickness of the voice_coil part is different on the two models - 2 mm and 5 mm. That accounts for some of the difference but not all of it. To find this, I compared their volumes using Tools -> Volume and that showed the full model didn't have 4 times the volume of the segment.

    2) The 360 degree model uses tet4 elements and the 90 degree one uses tet10 which will have very different stiffnesses and this is reflected in the very different fundamental frequencies (39 Hz vs 135 Hz) - after adjusting the Aluminium density for 1). I would try making the 360 degree model by using Mesh tools -> Rotate/copy on the 90 degree one to eliminate any differences due to the mesh. Of course, a correct solution should be independent of the element type, but you'd get that with refinement later on.




  • Thanks a lot Victor.
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