Elastic Plastic Model (1D)

Elastic plastic model in 1D problems

Elastic plastic model in 1D problems with example.

function [Material_State2,D]=Elastic_Plastic_Model_1D(Material,Material_State,e)

Input:

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Material: A variable containing material properties Material.E (modulus of elasticity), Material.f_y (yield stress), and Material.Ep (slope after yield stress)

Material_State: A history variable containing material state variables at previous increment or iteration. it includes Material_State.s (stress vector) , Material_State.e (strain vector) and Material_State.k (hardening parameter)

Initial values for these history variables should be zeros

IMPORTANT: for this model, this variable should be called from the last converged state of material ((i.e. end of previous increment not from the last iteration) in order to avoid spurious unloading. See Section 6.2 in Crisfrield book [1]

e: Strain vector in the current iteration.

Output:

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Material_State2: A history variable containing material state variables at current iteration

D: Tangent constitutive stiffness

References:

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[1] Crisfield, Michael A. Non-linear finite element analysis of solids and structures. Vol. 1. Wiley, 1993.