peteroznewman
Subscriber

Momidor,


This is not a crazy value, the stress is expected to be high at a crack tip. For simple geometries, there are even analytic equations to compute the stress. The linear elastic material model does not prevent the stress from exceeding yield. It's confusing that the Yield Strength is listed in the Engineering Data, but that is only there to compute Factor of Safety in post processing. It is not used during solving.


If you use large elements and ERESX, NO to prevent extrapolation, you can miss the true high value of stress for the linear elastic material. But as you use smaller and smaller elements and the mesh follows closely around that small curved crack tip, the result will converge on the true linear elastic material stress, which could be much higher even than you have shown.


To repeat what has been said before, these stresses cannot be achieved in a real material, or in a simulation that includes plasticity. Please add the bilinear isotropic hardening that includes the yield strength of the material and let plasticity distribute the stress around the crack tip.


Of course, there are convergence problems to solve once you do that, so you may have some new questions while resolving those problems.


Kind regards,


Peter