In-Situ Imaging of Spall Fracture

Spall fracture is a critical failure mode that occurs during highly impulsive loading in application areas such as ballistics and spacecraft shielding. During spall fracture, the interaction of shockwave rarefaction fans creates a region of high dynamic tensile stress inside the material and produces cracks and/or voids. Interrogation of the fracture process is traditionally limited to free surface velocity measurements during testing or post-mortem observations of the damage morphology. However, these methods provide indirect information on damage evolution, knowledge of which is critical for model development. Here, we present a technique for directly imaging the development of cracks during the spall fracture of polycarbonate, which will help guide our understanding of spall fracture development as well as provide invaluable input for spall models.