Hi,
I want to change the friction angle with the plastic strain in Abaqus following mohr coulomb model.
Vermeer and de Borst (1984) proposed an equation for frictional hardening and I want to use that. In their equation, the shear hardening parameter obtains from below equation(first picture) and then the friction angle changes with the shear hardening parameter.
So I have to use the usdfld code in my model.
I code that to calculate the shear hardening parameter, and then I put it equal to FIELD1. I attached the usdfld code(second picture) to this post.
can anybody tell me what is wrong in my code?
Do everybody have Vermeer equation code in Fortran for using in Abaqus?

12-0.JPG 13-1.JPG

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1 Comment
  1. Arie Koot
    Arie Koot 4 months ago

    Use total plastic strain and Cauchy for 3D
    strain=sqrt(0.5*(pe11-pem)^2+0.5*(pe22-pem)^2+0.5*(pe33-pem)^2+pe12^2+pe23^2+pe13^2)
    pem=(pe11+pe22+pe33)/3
    for explixit pe23=array(5) and pe13=array(6)
    for implicit pe23=array(6!) and pe13=array(5!)*
    for plainstrain: pe13 and pe23 do not exist

    *
    for explicit vgetvrm gives you e12,e23,e13
    for implicit you maybe get y12,y13,y23: you have to check this

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