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Hi all,

        I wrote VUMAT subroutine using fortran 77 for perfect plasticity unisng von mises plasticity..when analysed it using unidirectional tensile simulation for a simple cube model...it seems to me that it only goes through elastic deformation and not plastic...i tried to find out what is the error..but could not find it..could anyone please find what is the error in this code..i have attached the VUMAT code for the reference...thank you very much...

subroutine vumat(

Hi every one...



I finished my master in mechanical engineearing about eight month ago ... and in my Master career, I wrote a Fortran Finte element code with capabality of  mortar cantact analysis[1,2] and rate independent plasticity with kinematic and isotropic hardening and with large deformation capabilty for isotropic materials[3,4]. My code converges very well and I achieved quadratic convergence and I didn't use any comercial Fe packages like ansys and abaqus .....

The oral program is now available for you to view online: http://www.fatiguedamageconference.com/conference-programme.html

Help needed!! in Abaqus

I have UMAT written to update stress and material tangent components for a user defined material model. I need stretch ratio as an input for my material model. For this I am using deformation gradient from UMAT. Problem is, when there is constant strain (strain rate = 0), for example when material stretched to 100% strain (rubber) and then held at that strain for certain time to see stress relaxation, the deformation gradient should give the same value of 100% strain, but to my surprise this is changing. Can any one help me with this.   

dear all

 do anyone know how to simulate the plasticity of orthotropic material in abaqus cae?

  your help will be highly appreciated.

 best wish

kenneth