I suggest you use a Plasticity material model to prevent elements from carrying more stress than some limiting value. This is much simpler than using EKILL. The simplest plasticity material model is Bilinear Isotropic Hardening. Only two inputs are required: Yield Strength and Tangent Modulus. If you set the Tangent Modulus to 0, then the element will never carry more stress than the Yield Strength.

When you use Plasticity, you have to turn on some things under Analysis Settings. Turn on Auto Time Stepping and set the Initial and Minimum Substeps to 100, and the Maximum Substeps to 1000. Turn on Large Deflection.