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How to obtain the same result using user-defined hyperelastic material
Posted Jul 26, 2023, 10:26 a.m. EDT Studies & Solvers, Structural Mechanics, Physics Interfaces Version 6.0 0 Replies
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Dear Comsol Professionals:
I am currently facing difficulties obtaining consistent results using a user-defined function. My simulation involves modeling the torsion of a cylinder within a 3D Solid Mechanics model, using a nearly incompressible hyperelastic material (St Venant–Kirchhoff). The objective is to study the nondimensionalized normal stress (normal stress divided by shear modulus) on the upper face of the cylinder.
Initially, I utilized a built-in material model, which yielded an output of 10^-12 when the radial parameter (rad) was set to 4*10^-4. This result closely aligns with our estimations. However, when I applied the St Venant–Kirchhoff model as a user-defined function, the output increased to 39. It is important to note that I did not make any other changes to the simulation settings.
I am looking for the reasons causing this difference, and I would greatly appreciate any guidance on how to resolve this issue. For your reference, I have attached the mph file.
Here is my current setup: Hyperelastic material - user-defined - nearly incompressible. The user-defined model is defined in local variables (energy function). Fixed constraint- boundary 3 Rigid Connector - boundary 4 Connection type (Rigid) - center of rotation (centroid) - prescribed displacement (0,0,0)
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Hello Zack Pan
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