Implicit integration of constitutive equations in computational plasticity

ABSTRACT

The paper discusses an extension of the now standard Generalized Backward Euler (GBE) algorithm to a general class of elastoplastic constitutive equations for geomaterials, characterized by mechanical and non-mechanical hardening mechanisms. The resulting integration scheme is well suited for the application to relatively complex, three-invariant yield surface and plastic potential functions. A closed form expression for the consistent tangent stiffness matrix is derived for the general case, extending the work of [TAM 02a] for isotropic- hardening models. The application of the numerical procedure is discussed with reference to a constitutive model for chemical weathering of bonded geomaterials recently proposed by [TAM 02b]. Results from a series of numerical experiments are given to illustrate the accuracy and convergence properties of the algorithm.

RÉSUMÉ

KEYWORDS:

• Stress-point algorithm
• implicit integration
• consistent tangent stiffness

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