Symmetrization and applications of tangent stiffness matrix for UH model

Several common three-dimensional generalized methods for constitutive models and the superiority of the transformed stress (TS) method are analyzed in this paper. The non-associated flow of constitutive model based on the TS method is analyzed in detail. The symmetrization method of tangential stiffness matrix for the constitutive models is proposed. The essence of the constitutive models with non-associated flow of tangential stiffness matrix is the same as original one using the symmetrization method. The finite element analysis to some triaxial extension tests is carried out. Based on the analysis and the comparison, it is found that the symmetrization method of tangential stiffness matrix can improve the convergence of finite element analysis and reduce simulation time obviously.