Full‐field measurement of contact‐point and crack‐tip deformations in soda‐lime glass. Part‐II: Stress wave loading

Abstract

AbstractTransparent brittle ceramics such as soda‐lime glass pose unique challenges for performing full‐field optical measurement of deformations and stresses to characterize fracture and failure behaviors. Low fracture toughness coupled with high stiffness and elastic wave speeds are among the factors responsible for some of these challenges as deformations tend to be confined to an extremely small region near an almost mathematically sharp growing crack. Need for strong birefringence, elaborate optics, or lack of sufficient measurement sensitivity are some of the factors against legacy techniques such as photoelasticity, optical interferometry, and speckle methods, respectively, to study soda‐lime glass. Motivated by these factors, the feasibility of digital gradient sensing (DGS) method to measure impact induced deformations near a contact‐point and a dynamically growing crack‐tip in soda‐lime glass are demonstrated in this work. This second of a two‐part paper demonstrates the applicability of DGS for the problems under stress wave loading conditions. Ultrahigh‐speed photography (1 million frames per sec) in conjunction with DGS and a Hopkinson pressure bar to load soda‐lime glass specimens are employed. The optical measurements are postprocessed to obtain relevant engineering parameters and stress field near dynamically loaded crack‐tip, both while stationary and during propagation.