Quantification of increasing fracture toughness of glass matrix reinforced by alumina platelets composite

Abstract

A borosilicate glass matrix composite containing alumina platelets was considered to investigate toughening mechanisms and crack tip behaviour in dispersion reinforced brittle matrix composites. Fracture toughness was determined applying the chevron notched specimen technique and fractographic analysis was employed to reveal the active toughening mechanisms with increasing content of reinforcement. A roughness-induced shielding effect has been quantified to prove the relation between fracture toughness and fracture surface roughness. Theoretical calculations of the fracture toughness enhancement based on a modified crack deflection model developed by Faber and Evans, combined with the influence of the increase in Young’s modulus, were found to be in good agreement with experimental data. The crack deflection model was further extended to capture a synergy between crack deflection and the contribution of residual stresses to toughening in the investigated composites