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[helen.durand]

Hello,

For transient structural simulations, I have heard that it is bad decision to represent the mesh of an object with only a single layer of elements through the thickness. Can this be a cause of high element distortions?

If everything above is true, I am particularly interested in understanding why (mathematically or algorithmically) this is the case. Is there a mathematical or algorithmic explanation as to why having a single layer of elements would cause element distortions?

As an example mesh in case my description above is not clear, consider a plate with a mesh that looks something like this (please forgive my drawing):

Thank you!

[Nanda]

Hi helen,

When a thin part is modelled with solid elements, and the mesh is “large” so that there is only one element through the thickness, the results can be inaccurate.

The theory for this is solid elements have a limited ability to calculate large gradients Think of a thin fixed beam with a load acting vertically down at the centre. Bottom face is in tension, and the top face is in compression. A single solid element through the thickness may not calculate such a large change from tension to compression. Solid elements approximate the bending by elongation and contraction. They do not calculate a bending moment.

You can opt for shell elements here, by using midsurfacing technique. If you want to use solid elements only, it is better to create a mesh that has multiple elements through the thickness. However, if the part is in pure tension or compression, the number of elements through the thickness has no affect on the results.

If you want to have a better understanding of best practices for FEA analysis, have a look at this Ansys innovation course here:

Best Practices and Results Validation - ANSYS Innovation Courses

Thanks and Regards,

Nanda.

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