Hello,
I am trying to simulate penetration of a rubber membrane by a solid needle. This needs material failure to be simulated. Basically when the stress in a particular element in the rubber domain reaches the yield strength of the material, that element should be effectively deleted. As comsol doesnt have any such feature, I am trying to change the modulus of the element to a very low value. I use state variables feature introduced in COMSOL 5.5 to store the von Mises stress value in an element at the previous time step and use an if condition to set the young's modulus in the current time step. But the model is failing right after the switch happens in any one element.
Also this method is not completely correct as the von Mises stress in the element which has its modulus value reduced will also reduce due to which the modulus value in this element will switch back to its original value in the next time step.
It would really help if someone could help me out as to how I can pose this problem where the modulus in an element once changed to the new lower value stays at that same value.