Hi does anyone have a suggestion for how to model tool steel at failure. The structural materials I usually work with tend to fail plastically and so I would use a quasi-plastic approach to find the capacity but that doesn’t feel valid for something like 1.2379 at 59 hrc (That is D2 for Americans) it has a super high yield around 2000MPa, ultimate failure follows close to that obviously.
I am not sure calculix has an element for this? Many years ago I worked on an analysis for Boeing modeling seat track attachments and in Abaqus we used some sort of explicit analysis to model the metal disappearing as it failed. It correlated really nicely in testing but I don’t have the details (they didn’t like it when you took stuff like that home)
Abaqus offers various damage initiation and evolution criteria along with material deletion. One of the most common models for high speed explicit dynamics (such as impact analyses) is Johnson-Cook plasticity with strain rate dependence and failure. I’ve seen some work on that in CalculiX GitHub repository at the beginning of this year. Anyway, for now there’s not much you can do when it comes to such advanced material models apart from using subroutines like umat.
What about a bilinear plasticity with zero tangent Modulus?. If the problem is force driven it typically fail at the ultimate strength point.
Convergence failure, which is typically seen as a problem, can be an indicator of material rupture.
These material models is available trough MFront CalculiX integration, however it may have some limitation. For high strain rate effect due to impact load, Johnson Cook model can be use but no damage failure is consider. In case of ductile failure material models, Gurson–Tvergaard–Needleman is available but it seems limited to quasi static load only.