Dynamic mechanical response of damaged alumina AD995

Abstract

This paper explores the compressive responses of alumina ceramics subjected to various levels of pre-damage via internal cracking. Pre-damage is achieved by subjecting the samples to thermal shock. Mechanical loading is performed using a load frame for quasi-static strain rates and a Kolsky bar for dynamic strain rates. Digital image correlation is used to obtain two-dimensional strains alongside independently measured applied stresses. Data acquisition used in this study allows for the calculation of apparent elastic moduli as a function of strain. This allows for the study of change in mechanical response with strain, strain-rate, and level of pre-damage. There is a complex interaction between pre-damage and compressive loading, leading to mechanical damage accumulation being divided into three stages rather than a single damage accumulation function. It was also found that shear modulus change was more indicative of physical failure phenomena during loading than Young’s modulus or Poisson’s ratio changes.