Spall-Fracture Physics and Spallation-Resistance-Based Material Selection
ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD SURVIVABILITY MATERIALS BRANCH
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Spallation is a fracture mode commonly observed in ballisticallyblast-wave-loaded structures. The interaction between decompression waves generated within the target structure produces tensile stresses which, if of a sufficient magnitude, may cause material damage and ultimate fracture spallation. In this study, the phenomenon of spall-fracture is analyzed within a one-dimensional Lagrangian framework. Two distinct analyses are carried out. Within the first analysis, decompression waves are treated as decompression shocks, which simplified the analysis and enabled the formation of spallation-strength-based material index. In the second analysis, decompression waves are treated as smooth centered simple waves. This increased the fidelity of the computational analysis, but the material-selection procedure could be done only numerically and an explicit formulation of the spallation-strength-based material-selection index could not be carried out. Overall, the two analyses yielded similar results for the spallation-strength-based material-selection criterion suggesting that the simpler decompression shock based one is still adequate for use in the material-selection process.