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I am using exponent Drucker-Prager model at the moment, is there anyone can tell me where the follow exponent D-P eqation comes from originally?

(σ e)(σ e)=λ(σ_t)(σ_t)-3(λ-1)σ_mσ_t

Where λ= is hydrostatic stress sensitivity parameter and equal to σ_c/σ_t, σe is effective stress, σ_m is hydrostatic stress, σ_c, σ_t are stresses under compression and tension, respectively.

I am doing my master thesis on crash simulation of plywood (7 layers-orthotropic material) structures in buses using explicit LS-DYNA FE program. I would like to include failure in my model. Right now I am working on Mat_054_55 (MAT_ENHANCED_COMPOSITE_DAMAGE…..material model from LS-DYNA material library).

Mat_054_55 allows me to get failure by defining anyone of the following parameters,

In a recent rapid communication (see attached paper), using principles of pattern formation, we expose some simple stategies to reliably produce perfect long range order in self-assembling systems. Most self-assembling systems exhibit short ranged order. This imperfection is detrimental to several practical applications. It is almost always possible to produce perfect patterns in small domain sizes but self-assembly over a larger areal span results in defects.

I'm trying to model a composite structure with shell 99 element in Ansys.

I set the thickness and material no. in real constant and prepare an orthotropic material property for that. While ploting the result, as I expect to get the stresses among layers different from other points, but the result is a kind of uniform isotropic graph.

I don't know if any setting other than real constant and material property should be done to get a true result or not. and if I'm true then how can I read the true result.

I will appreciate any help.

I would like to know the difference between Effective Strain, Effective Plastic Strain and Effective Failure Strain.

Hi,

     Thanks for the earlier feedback. I was able execute the user subroutine (UMAT) along with *.inp file only to land into new type of error message:

fatal error lnk1112: module machine type 'IA64' conflicts with target machine type 'X86'

Can somebody please help me to understand what this error means and how to overcome this monster.

I have already installed intel fortran compiler, and microsoft visual studio for windows. 

As always thanks for the much needed help.