Response of Materials to Various Shock Loading Conditions Generated by Plate Impact Experiments

The response of materials to shock loading has been investigated through use of a plate impact experimental technique. A single stage gas gun was utilized to drive projectiles to velocities between 50-500 m/s, facilitating investigations into low to moderate shock loading conditions. Temporal records of the dynamic events were captured with the use of commercial manganin stress gauges that were embedded within layers of test material. Within this thesis, there is a bimodal theme. The first portion of this thesis investigated the spall fracture of cast irons with varying microstructure. Although the study of the spall fracture of materials is a common theme in literature, there exists a noteworthy scarcity of research specific to cast iron. Given that cast iron is one of the most widely utilized materials in engineering structures, this research was pursued in an effort to characterize its strength and identify the fracture mechanisms and kinetics associated with its failure process. The second portion of this thesis involved the development of a new technique that could be utilized to generate multiple Hugoniot states in a single experiment. Generation of a material’s Hugoniot is a fundamental theme in shock wave studies because it allows researchers to determine all mechanical and thermodynamic properties associated with dynamic loading conditions. Traditionally, the locus of points necessary to construct a material’s Hugoniot is obtained through a rigorous series of experiments, where each test produces a single data set. By considering the shock wave processes associated with layered plates, a new method was developed that will significantly reduce the process of obtaining material Hugoniots. Within the study of the spall fracture of cast iron, experiments were designed to induce an extreme tensile state within test samples from the interaction of decompression waves. The dynamic fracture strength, known as spall strength, was determined from temporal records of the stress evolution inside the samples. In order to encompass a vast majority of castings typical to industry, five separate cast irons were tested. Four of these castings consisted of gray cast iron with graphite in flake form, where three were classified as Type VII A2 and the other contained a bimodal distribution of Type VII A4 and VII D8. The fifth casting consisted of ductile cast iron with graphite in nodular form, classified as Type I with an average of 200 nodules per square millimeter of size class 5. The spall strength for the Type VII