A FINITE-ELEMENT APPROACH TO ANISOTROPIC DAMAGE OF DUCTILE MATERIALS IN LARGE DEFORMATIONS .1. AN ANISOTROPIC DUCTILE ELASTIC-PLASTIC-DAMAGE MODEL

During past decades, many material models using the continuum damage m echanics (CDM) approach have been proposed successfully in the small d eformation regime to describe inelastic behaviors and fracturing pheno mena of a material. For ductile materials, large deformation takes pla ce at the level of damage appearance. Damage is anisotropic in nature. In this paper, the ductile damage at finite deformations is modeled a s an anisotropic tensor quantity. Then, a fourth-order symmetric stres s correction tensor is proposed for computationally efficient and easy implementation in the finite element formulations. Consequently, an e xplicit form of the fourth-order constitutive equations of the propose d elastic-plastic-damage model is derived. Both isotropic and kinemati c hardening effects are included in the formulation. The new constitut ive model can predict not only the elastic-plastic behaviors, but also the sequential stiffness variations of ductile materials. An evaluati on of the constitutive and damage evolution equations is presented.