[Feature]: Verlet Time step

[CWillberg]

What are you trying to do and how would you want to do it differently?

I would like to have a step width prediction for anisotropic material.

Is it something you currently cannot do? Is this related to an issue/problem?

You assume isotropic material to predict the step width. It can lead to to large time steps and instable computations.

Implementation details

No response

Would you be willing to submit a PR?

Yes

[JTHesse]

Do you know a paper on this topic? Currently, we are using this as a bulk modulus for the calculation:

s11 = 1 / E_x
s22 = 1 / E_y
s33 = 1 / E_z
s12 = -nu_xy / E_x
s23 = -nu_yz / E_z
s13 = -nu_xz / E_z
bulk_modulus = 1 / (s11 + s22 + s33 + 2 * (s12 + s23 + s13))