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This method involve an explicit relationship between increments of stress and strains. Thus, elasto-plasticty is described by:

 

                                       

where Eep represents the generalized tangent constitutive matrix.

 

For perfect plasticity in the absence of hardening or softening the tangent consitutive matrix can be obtained particularizing the equation 51:

 

                                                 

The body loads Fbi in the stress redistribution process are reformed at each iteration by summing the following integral for all elements that posses yielding Gauss integration points:

 

                                       

This method is used in conjunction with the forward Euler approach to integrating the elasto-plastic rate equation, extrapolating from the point at which the yield surface is crossed.

 

 

 

 

 

 

 

 

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