YIELD SURFACES OF MATERIAL COMPOSED OF POROUS AND HETEROGENEOUS MICROSTRUCTURES CONSIDERING PHASE DEBONDING

Abstract

THIS WORK DEALS WITH NUMERICAL SIMULATION OF THE MECHANICAL BEHAV-IOR OF MATERIALS COMPOSED OF HETEROGENEOUS DUCTILE MICROSTRUCTURES USING A MULTI-SCALE APPROACH CONSIDERING PLASTICITY PROCESSES AND PHASE DEBONDING. DUE TO FEW STUDIES ABOUT YIELD SURFACES OF METAL MATRIX COMPOSITES (MMC) WITH WEAK INTERFACES PRESENTED IN THE LITERATURE, THE MAJOR GOAL OF THIS WORK IS TO PROPOSE YIELD SURFACES FOR METAL MATRIX COMPOSITES REINFORCED BY RIGID INCLUSIONS. THE YIELD SURFACES ARE OBTAINED FOR REPRESENTATIVE VOLUME ELEMENTS (RVES) OF MATERIALS PRESENTING PERFECTLY BONDED INCLUSIONS AND PHASE DEBONDING IN THE INTERFACE ZONE. THE MATRIX IS CONSIDERED AN IDEALLY PLASTIC MATERIAL GOVERNED BY VON MISES MODEL, WHEREBY THE INTERFACE ZONE IS MODELED BY MEANS CONTACT AND FRACTURE CONSTITUTIVE MODELS INCORPORATED IN A FINITE ELEMENT DEVELOPED FOR THIS PROPOSAL. ALSO, RVES CONTAINING DIFFERENT VOLUME RATIOS OF VOIDS FOLLOWING DIFFERENT DISTRIBUTIONS ARE ANALYZED. CONSIDERING THE PHASE DEBONDING, FOR COMPRESSIVE LOADINGS THE RVE BEHAVES LIKE RVE WITH PERFECTLY BONDED INCLUSIONS WHEREAS FOR TENSION LOADINGS THE RVE PRESENTS A BEHAVIOR QUITE SIMILAR TO THE ONE WITH VOIDS. IN THE OTHER HAND, THE CONCENTRATION OF VOIDS IN THE RVE DECREASES ITS MECHANICAL STRENGTH.