Element Weakening Method (EWM) in ABAQUS 6.12/6.13

Hello All,

Currently,I am modeling elasto-plastic buckling of laminated composites. I started with 3 layers (fiber-matrix-fiber) respresenting unit cell of composite. The model is made with material non linearity and incremental approach - Modified Riks Algorithm has been used for buckling analysis. My try would be to get plastic buckling in the model. For this I need to introduce "Element Weakening Method" (EWM) which allows user's choice to assign weak properties or reduced stiffness to the selected elements. Consequently, this helps in propagating damage.

In the past, many people have done this with writing subroutines, but I am particulary interested in doing by ABAQUS/CAE. 

Does any one knows how to include EWM - element weakening method in ABAQUS 6.12/6.13?  

Thanks,

Jay Patel