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Modelling Metallic Diaphragm
Posted Feb 11, 2013, 9:39 a.m. EST Geometry, Materials, Mesh, Structural Mechanics Version 4.2 1 Reply
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I am a novice COMSOL user using the software for a student project so apologies if my problem below seems simple.
I have a 2D axisymetric model of a thin metallic diaphragm (approx 25mm di and 0.025mm in thickness).
The diaphragm is deformed by a uniform pressure load and fixed around its perimeter.
To begin I have used a simple flat diaphragm and the model produces deflection results that agree well with theory for small deflections (up to approx 2xthickness)
When a greater pressure differential is applied the model appears to become over "stiff" and the predicted deflection is significantly below that given by theoretical results.
Currently I have tried varying the mesh size and shape (quad/tri) with no significant change in the result. I have also trialled both linear and quadratic elements with no significant improvement (the element quality is always extremely high due to the simple geometry).
I am using a linear elastic model with non-linear geometry enabled. Is this Ok to use when there is considerable strain in the model?
I would be great full if anybody has any feedback on how to improve the model / experience with a similar model or ideas on why it may be differing from theory?
Thanks in advance!
Matt
I have a 2D axisymetric model of a thin metallic diaphragm (approx 25mm di and 0.025mm in thickness).
The diaphragm is deformed by a uniform pressure load and fixed around its perimeter.
To begin I have used a simple flat diaphragm and the model produces deflection results that agree well with theory for small deflections (up to approx 2xthickness)
When a greater pressure differential is applied the model appears to become over "stiff" and the predicted deflection is significantly below that given by theoretical results.
Currently I have tried varying the mesh size and shape (quad/tri) with no significant change in the result. I have also trialled both linear and quadratic elements with no significant improvement (the element quality is always extremely high due to the simple geometry).
I am using a linear elastic model with non-linear geometry enabled. Is this Ok to use when there is considerable strain in the model?
I would be great full if anybody has any feedback on how to improve the model / experience with a similar model or ideas on why it may be differing from theory?
Thanks in advance!
Matt
1 Reply Last Post Feb 12, 2013, 11:15 a.m. EST
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Posted:
1 decade ago
Hi
so far I have always got very good agrement between COMSOL and analytical values, but sometimes one go outside the linear regime, then you should turn on the "solver - Geometrical non-linearities" to get better results, perhaps that is your case ?
--
Good luck
Ivar
so far I have always got very good agrement between COMSOL and analytical values, but sometimes one go outside the linear regime, then you should turn on the "solver - Geometrical non-linearities" to get better results, perhaps that is your case ?
--
Good luck
Ivar