Search

This paper develops an adaptive concurrent multi-level computational model for multi-scale analysis of composite structures undergoing damage initiation and growth due to microstructural damage induced by debonding at the fiber-matrix interface. The model combines macroscopic computations using a continuum damage model with explicit micromechanical computations of stresses and strain, including explicit debonding at the fiber-matrix interface. The macroscopic computations are done by conventional FEM models while the Voronoi cell FEM is used for micromechanical analysis. Three hierarchical levels of different resolution adaptively evolve in this to improve the accuracy of solutions by reducing modeling and discretization errors. There levels include: (a) level-0 of pure macroscopic analysis using a continuum damage mechanics (CDM) model; (b) level-1 of asymptotic homogenization based macroscopic-microscopic RVE modeling to monitor the breakdown of continuum laws and signal the need for microscopic analyses; and (c) level-2 regions of pure micromechanical modeling with explicit depiction of the local microstructure. Numerical examples are solved to demonstrate the effectiveness and accuracy of the multi-scale model.To use the framework of this multi-scale computational model for ductile fracture analysis, This paper develops an accurate and computationally efficient homogenization based continuum plasticity-damage or HCPD model for macroscopic analysis of ductile failure in multi-phase porous ductile materials, such as cast aluminum alloys. The overall framework of the HCPD model follows the structure of an anisotropic Gurson-Tvergaard-Needleman (GTN) type elasto-plasticity model for porous ductile materials. To account for orientation dependence, the anisotropic HCPD model is expressed in the evolving material principal coordinate system and is assumed to remain orthotropic in it throughout the deformation history. Parameters in this model are calibrated from results of homogenization of microstructural variables obtained by LE-VCFEM analysis of the microstructural RVE containing inclusions, matrix and voids. Anisotropy parameters are found to evolve with plastic deformation in the microstructure. The model also incorporates a novel void nucleation criterion obtained by homogenizing micromechanical damage evolution by inclusion and matrix cracking. The overall model also incorporates realistic estimates of RVE length scales in the microstructure, as well as non-local characteristic length scales in the macrostructure. Comparison of the anisotropic HCPD model results with homogenized micromechanics results shows excellent agreement. On the other hand, the HCPD model has a huge efficiency advantage over the micromechanics models and is hence a very effective tool in making macroscopic damage predictions in structures with explicit reference to the microstructural composition.