Initial stress method
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This method involve an explicit relationship between increments of stress and strains. Thus, elastoplasticty is described by:

(187) 
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:

(188) 
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:

(189) 
This method is used in conjunction with the forward Euler approach to integrating the elastoplastic rate equation, extrapolating from the point at which the yield surface is crossed.

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