non convergence in hyperelastic model for heavy loads

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Thanks for the fruitful information.

I am facing an issue with nonconvergence of nearly bat 30kPa while applying compressive load up to 300kPa on ecoflex 0030 material. Nonlinear solid mechanics has been used with different hyperelastic models such as mooney rivlin 20 parameters, odgen, and neo Hookean. Can somebody help me with the issue of finding out the probable reason behind nonconvergence?

Note its a 2D block of 5mm by 2mm made of ecoflex 0030.

Also, do this problem need to be solved with moving mesh? I am facing a problem with moving the mesh as I am unable to describe/utilize it properly.



1 Reply Last Post 2024年8月1日 GMT-4 10:47
Henrik Sönnerlind COMSOL Employee

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Posted: 2 hours ago 2024年8月1日 GMT-4 10:47
Updated: 2 hours ago 2024年8月1日 GMT-4 10:49

I think the problem is that the singularity at the two ends of the fixed constraint causes extreme strains, and a very high biaxiality ratio. This throws the hyperelastic models out of the stability region. If you make a finer mesh there, the failure will come earlier, since the singular strains are then resolved into even higher values.

You may need a more realistic boundary condition.

You cannot use a moving mesh in a domain controlled by Solid Mechanics. Moving mesh would typically be used in a fluid domain which is deformed by an adjacent solid.

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Henrik Sönnerlind
COMSOL
I think the problem is that the singularity at the two ends of the fixed constraint causes extreme strains, and a very high biaxiality ratio. This throws the hyperelastic models out of the stability region. If you make a finer mesh there, the failure will come earlier, since the singular strains are then resolved into even higher values. You may need a more realistic boundary condition. You cannot use a moving mesh in a domain controlled by Solid Mechanics. Moving mesh would typically be used in a fluid domain which is deformed by an adjacent solid.

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