Effects of Non-Uniform Particle Distributions on Damage Evolution in Pre-Cracked, Particulate Composite Specimens

Abstract

Particle distribution in a particulate composite, in general, cannot be controlled so that a composite specimen can have a non-uniform particle distribution. This study examines the effects of non-uniform particle distributions in particulate composite specimens made of hard particles embedded in a soft rubbery binder on the crack tip behaviour, using a numerical technique called a micro/macro-approach. This technique couples the micro-level and macro-level analyses. The micro-level analysis uses a three-dimensional unit-cell model and a continuum damage theory at the constituent material level (the particles and the binder) while the macro-level analysis utilizes the finite element method at the smeared composite specimen level. Both analyses are conducted in tandem as damage evolves in the specimens. The study investigates the damage evolution around the crack tip, the resulting stress variation near the crack tip, and the crack opening displacement for several specimens with different particle distributions. All the specimens have the same average particle volume fraction so that all of them have the same average effective elastic modulus. Every specimen has multiple zones, each of which has a uniform particle distribution. A crack is located in a single zone. The numerical results indicate a possible wide variation of crack tip behaviours, for example, with respect to fracture strength from specimen to specimen, depending on the state of particle volume distribution and the location of the crack.