Abstract
This study presents a thermodynamically consistent coupled damage-inelasticity model for epoxy. It introduces an asymmetric von Mises yield criterion for varying hydrostatic stress dependence in tension and compression. Damage in the material is defined as a three-dimensional entity, that is, the damage is assumed as a spherical void in a cubical representative volume element (RVE). An explicit stiffness reduction model is presented using micromechanical analysis of void-based RVE. A two-step radial return method with an associative flow rule, coupled with damage growth, is developed for the evolution of inelastic strains. The proposed model is implemented in a user material UMAT subroutine and integrated into the commercial solver ABAQUSTM. The effectiveness of the model is evaluated by comparing its predictions with the material data available in the literature. Further, an experimental investigation is carried out on an in-house epoxy, and the proposed model is used to capture the tensile and compressive behavior. Eventually, the model is applied to a micromechanical analysis of a unit cell RVE with fibers packed in a diamond arrangement to demonstrate its efficacy in predicting the macro-response of a unidirectional composite.
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