Dynamic crack propagation in layered transparent materials studied using digital gradient sensing method: Part-ii

Abstract

Dynamic fracture behavior of bi-layered PMMA samples are studied using Digital Gradient Sensing (DGS) in conjunction with high-speed photography. DGS exploits elasto-optic effect exhibited by transparent solids subjected to a non-uniform state of stress causing deflection of light rays propagating through the material. The current work builds on authors’ previous report concerning crack trapping, interfacial bifurcation, and mixed-mode penetration into the second layer when a dynamically growing mode-I crack in the first layer encounters a normally oriented interface of different strengths. The current work specifically focuses on the role of the interface location within the bi-layered specimen relative to the initial crack tip on fracture behavior with an intention of examining the effect of the incident crack speed and the associated stress intensity factors for select interfacial fracture toughness. The location of the interface is varied sequentially from ‘near’ to ‘far’ from the initial notch tip to accomplish this task. Preliminary results suggest that crack growth in both the interface and the second layer are greatly affected by the location of the interface. That is, the velocity and stress intensity factors of the incident crack affect the outcome of the overall fracture behavior of bi-layered samples including interfacial trapping and penetration into the second layer.