Hi,

I’m working on validating my code with Ansys. As you can see in this topic, the displacements are quite close with only minor differences. However, for the von Mises stress, the discrepancy is larger:

I’ve been following this tutorial by @dokken. However, since I need the von Mises stress at the nodes and I’m using a serendipity family, I’ve interpolated it as follows:

```
V_von_mises = fem.FunctionSpace(domain, ("S", 1))
stress_expr = fem.Expression(von_Mises, V_von_mises.element.interpolation_points())
stresses = fem.Function(V_von_mises)
stresses.interpolate(stress_expr)
```

I suspect that the error might be in this interpolation.

Does this method calculate the von Mises stress at the Gauss points? I’m asking because Ansys calculates it at the Gauss points and then interpolates to the nodes.

Any suggestions or insights would be greatly appreciated.

Thanks,

João