Role of material properties and mesostructure on dynamic deformation and shear instability in Al-W granular composites

TL;DR

This study investigates how material properties and mesostructure influence dynamic deformation and shear instability in Al-W granular composites, combining experiments and numerical modeling to reveal mechanisms of shear localization.

Contribution

It provides new insights into the role of particle bonding, size, and arrangement in shear localization in Al-W composites through combined experimental and numerical analysis.

Findings

Bonding between Al particles facilitates shear localization.

Shear localization is driven by high strain flow of soft Al around rigid W particles.

W particles influence the initiation and growth of shear bands.

Abstract

Dynamic experiments with Al-W granular/porous composites revealed qualitatively different behavior with respect to shear localization depending on bonding between Al particles. Two-dimensional numerical modeling was used to explore the mesomechanics of the large strain dynamic deformation in Al-W granular/porous composites and explain the experimentally observed differences in shear localization between composites with various mesostructures. Specifically, the bonding between the Al particles, the porosity, the roles of the relative particle sizes of Al and W, the arrangements of the W particles, and the material properties of Al were investigated using numerical calculations. It was demonstrated in simulations that the bonding between the "soft" Al particles facilitated shear localization as seen in the experiments. Numerical calculations and experiments revealed that the mechanism of the shear localization in granular composites is mainly due to the local high strain flow of "soft" Al around the "rigid" W particles causing localized damage accumulation and subsequent growth of the meso/macro shear bands/cracks. The "rigid" W particles were the major geometrical factor determining the initiation and propagation of "kinked" shear bands in the matrix of "soft" Al particles, leaving some areas free of extensive plastic deformation as observed in experiments and numerical calculations.