runge-kutta

Hello everyone,

I'm currently doing an analysis on the convergence rate of an incremental model that I have implemented in ABAQUS using a UMAT. Here's the BIG lines of the problem:

1)In UMAT : Solution of a differential equation using explicit Runge-Kutta 4 (RK4), which has a 4th order convergence rate, yields the stress state "S". (In my problem, stresses are applied)