High-Speed Transmission Shadowgraphic and Dynamic Photoelasticity Study of Stress Wave and Impact Damage Propagation in Transparent Materials and Laminates using the Edge-On Impact (EOI) Method; Conference paper with briefing charts

摘要

Operation Iraqi Freedom has clearly demonstrated the criticality of transparent armor in many army systems. As the threats have escalated and become more varied, the challenges for rapidly developing optimized threat specific transparent armor packages have become extremely complex. In order to accelerate the development of validated design and predictive performance models, the Army Research Laboratory, the U.S. Army Tank Automotive Research Development and Engineering Center, and the Material Center of Excellence at Johns Hopkins University have entered into a collaboration with The Ernst-Mach Institute (EMI) of Efringen-Kirchen, Germany. The unique, fully instrumented Edge-on Impact facility at EMI, modified for dynamic photoelasticity, is being used to quantify stress wave propagation, damage nucleation and propagation during high velocity impacts. Summarized in this paper are a selection of results on monolithic and laminated glass (Starphire trademark) and AlON, a polycrystalline transparent ceramic. Crack, damage and stress wave velocities have been determined directly. In addition, the stress wave and damage retardation by various thickness bonding interfaces has been measured: for a 5.08 mm interlayer, a delay of 1.7 microsec was determined. A computational model was constructed using ABAQUS Explicit to simulate the elastic wave propagation within AlON. The simulations show that the damaged region observed in the experiments corresponds essentially to the region that has observed shear as a result of the wave propagation. These results are a critical tool to corroborate and refine existing materials and transparent armor package models by providing insight and critical data into the role of different materials and interfaces that can eventually guide materials and laminate design.