Material data ordering in Solid Mechanics simulations: Voigt vs. Standard

Posted 09.01.2026, 15:56 GMT-5 Materials, Structural Mechanics Version 6.4 2 Replies

Noam Amozeg

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I'm simulating mechanical resonators made of anisotropic materials and am struggling to understand COMSOL's expected input for the material's elasticity tensor.

Under the Linear Elastic Material node, there's a dropdown to choose "Material data ordering" and can be toggled to select either "Standard" or "Voigt". Under the Materials node, you can either specify a material's "Elasticity matrix", or its "Elasticity matrix, Voigt notation."

I ran the same study on the same component 4 times with all possible permutations of the toggles above, and I'm not understanding how to interpret the results.

Study 1: "Standard" ordering and "Elasticity matrix." Study 2: "Standard" ordering and "Elasticity matrix, Voigt notation." Study 3: "Voigt" ordering and "Elasticity matrix." Study 4: "Voigt" ordering and "Elasticity matrix, Voigt notation."

Studies 1 and 3 gave identical results, while studies 2 and 4 also gave identical results. This makes it seem like the "Material data ordering" toggle has no effect on simulations, so what does it do? I understand that changing between "Elasticity matrix" and "Elasticity matrix, Voigt notation" while inputting the same tensor values changes the order of the shear terms, so seeing different results between those studies was expected.

In each case, I set the elasticity matrix to be assigned from the material rather than choosing "User defined." Is the toggle really only necessary when inputting "User defined" material properties?

I compared these 4 studies with a study where the "Material symmetry" was set to "Crystal" and inputted the c_ij values for the elasticity tensor (in Voigt notation); and this study gave identical results to studies 2 and 4.

What is the "proper" way to set the "Material data ordering" and input elasticity tensors in these simulations?

Thanks!

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2 Replies Last Post 12.01.2026, 09:37 GMT-5

Henrik Sönnerlind COMSOL Employee

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Posted: 8 hours ago

Your observation that the setting in the Linear Elastic Material does not matter as long as the data is given under the Material node is correct.

This behavior is a legacy thing. In earlier versions of COMSOL, these two settings had to match; if not an error would be thrown. But since several versions back, there is a silent conversion if the data in the Material node can be mapped to what is requested in the Linear Elastic Material. In your case, the conversion (obviously) can go in both directions, so all four combinations are valid.

There are other examples where the conversion is unidirectional. You can for, for example, use material data given for an isotropic material as a material that is formally orthotropic or anisotropic.

If you add an Elasticity matrix under Material, and then select Voigt ordering in Linear Elastic Material, you can see a special icon in the Material Contents section in the Material node indicating the conversion, and even how the conversion is done.

-------------------
Henrik Sönnerlind
COMSOL

Noam Amozeg

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Posted: 3 hours ago

Thanks for the answer! I appreciate your time and help!

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