Mixed-Mode Dynamic Fracture Behavior of Soda-Lime Glass Studied using Digital Gradient Sensing Method

Abstract

Structures often fail under combined tension and shear loads, and hence, it is critical to understand the mixed-mode fracture behavior of materials. In this work, the dynamic mixed-mode fracture of soda-lime glass (SLG) was experimentally investigated using the full-field optical method—digital gradient sensing (DGS). Freestanding single-edge notched specimens were subjected to reverse impact loading using a modified Hopkinson pressure bar. By eccentrically loading the specimens parallel to the initial notch, various mode mixities, from pure mode-I to nearly pure mode-II conditions, were achieved by changing the amount of eccentricity. Ultrahigh-speed photography was utilized in conjunction with DGS methodology to measure the angular deflection of light rays that are proportional to in-plane stress gradients in two orthogonal directions. In this ongoing research, mode-I and mode-II stress intensity factor histories prior to and at crack initiation will be evaluated in the next phase by performing an over-deterministic least squares analysis on optically measured full-field data. From the critical stress intensity factors at crack initiation, a fracture envelope for SLG encompassing different mode mixities will be developed. From the fractured samples, kink angles will be measured and compared with established fracture criteria.