How to define Secant and Tangential Stiffness Matrices for Nonlinear analysis using 3-node axial (rod) finite elements?

I am trying to program a Newton-Raphson Nonlinear solver for Material nonlinearities (i.e. bilinear material) and i don't know how to define Tangential and Secant Young Moduli since the 3-node...

15 February 2020 6,544 4 View