Evaluation of Stochastic Microfracture Process of Particle Dispersed Composites

Abstract

Fracture of glass and ceramics is essentially brittle and a probabilistic phenomenon. Acoustic emission (AE) is a phenomenon due to microfractures before the final fracture. We have considered the models for microfracture process and proposed the method to analyze the obtained experimental data from AE measurement. We consider two models for microfracture, (1) microfracture occurs independently before the final fracture, and (2) a crack propagates from a microfracture as an origin. We obtain the probability distribution functions for microfracture stress and for microfracture location. The borosilicte glass composites were used in experiments, which have participated anorsite around Al2O3, particles. The four point bending tests were carried out in both air and vacuum by using the specimens of 3 by 4 by 40 mm. AE sensors were attached at the both ends of specimen and AE waveforms of two channels were recorded. One dimensional locations of AE signals were analyzed. Microfracture process of borosilicte glass composites was analyzed by these models. The analysis of microfracture stress and location from AE data demonstrates that the increase of humidity changes the microfracture process of the materials from the independent microfracture type to crack growth type. The experimental results of microfracture stress and location could be explained by the proposed models.