A Multiscale Characterization and Analysis Methodology for Ductile Fracture in Heterogeneous Metallic Materials

A Multiscale Characterization and Analysis Methodology for Ductile Fracture in Heterogeneous Metallic Materials

Abstract

Heterogeneous metallic materials e.g. cast aluminum alloys or metal matrix composites arewidely used in automotive, aerospace, nuclear and other engineering systems. The presence ofprecipitates and particulates in the microstructure often affect their failure properties like fracturetoughness or ductility in an adverse manner. Important micromechanical damage modes that areresponsible for deterring the overall properties include particulate fragmentation, debonding atinterfaces and ductile matrix failure due to void initiation, growth and coalescence, culminating inlocal ductile failure. The complex interaction between competing damage modes in the presenceof multiple phases makes failure and ductility prediction for these materials quite challenging.While phenomenological and straightforward micromechanics models have predicted stress-strainbehavior and strength of multi-phase materials with reasonable accuracy, their competence inpredicting ductility and strain-to-failure, which depends on the extreme values of distribution, isfar from mature. To address the needs of a robust methodology for ductility, the work will discussa comprehensive multi-scale characterization based domain decomposition method followed by amulti-scale model for deformation and ductile failure. Adaptive multi-scale models are developedfor quantitative predictions at critical length scales, establishing functional links betweenmicrostructure and response, and following the path of failure from initiation to rupture. Thework is divided into three modules. (i) Multi-scale morphology based domain partitioning todevelop a pre-processor for multiscale modeling, (ii) Enriched Voronoi Cell FEM for particle andmatrix cracking leading to ductile fracture and (iii) Macroscopic homogenization continuumdamage model for ductile fracture. Finally a robust framework for two-way multi-scale analysismodule is the coupling of different with different inter-scale transfer operators and interfaces isdeveloped.