Classification of Microfracture Process Type in Glass Matrix Composites by Quantitative Acoustic Emission Method

Abstract

Particle dispersed glass matrix composites have been developed in order to increase the strength of glass, and microfracture before the final fracture during bend test has been observed in many ceramics and glass composites as acoustic emission (AE) signals. Stochastic process treatment for microfracture of these composites was performed to understand the mechanical properties of these materials. Bending strength of these materials was measured as various conditions in loading rate and atomoshere. AE behavior during these tests was also detected with two transducers and a two-channel waveform acquisition system to evaluate the microfracture location in the materials. Microfracture processes during bending tests were clealy classified into four major types from the results of source location of AE, that is, (i) unstable fracture type, (ii) crack propagation type, (iii) transition type from random microfracture to crack propagation and (iv) competition type between random microfracture and crack propagation. The effect of loading rate, atmosphere and volume fraction of reinforcing particles on microfracture process was discussed.