contact

[halleluja]

Hi everyone,

i am simulating a cutting process. I use a shape cutting tool which is a fixed rigid body and the workpiece moves towards it. I use node to segment strategy, workpiece is the slave body and the cutting tool is master body. Since the cutting tool consists of just two straight line (see pic) and is fixed and rigid, i only need to modify  the element residuum p and the element stiffness matrix of the subroutine elmt of workpiece. It works fine till the time step shown in the pic, but at the next time step, the computation will break up because some element have negative jacobian determinant. I think it is because at next time step two nodes of the pink element will both contact the cutting tool. But i don't know why if two nodes of one element contact the master body, it will cause problem. Can you give me some idea?

Best

[Prof. R.L. Taylor]

It is very hard to understand what might be going on without knowing which elements you are using and the material model used.

It could be that the load steps are too large as the contact evolves, however, I see some elements that have quite bad aspect ratios.  Maybe smoothing the mesh before solving will help.

Have you specified the tool as rigid or are you trying to use a high modulus?  If the latter, maybe making it rigid will help.

Always good to let us have a mesh to test.