Metal Melting and Dynamic Stress

I never wor in this program. But singulariti is because matrix is near by zero. You can do next, try to change sistem of solving. Method like gradient, Gauss, or some other. Also try to find to change numerical solving node.

In real life you never have a theoretically sharp corner. You could avoid it introducing a small 45° phase.

COMSOL is avery good soft so that you could obtain good results.

Assuming it is a round cake the piece is taken from use the circular interpolations to produce radius