Tensile Strain as a Criterion for Spallation in Metals.
EFFECTS TECHNOLOGY INC SANTA BARBARA CALIF
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Spallation data has, for the most part, been obtained from plate impact experiments. Recently, spallation data for metals has become available using a high energy electron beam to generate stress waves by rapid uniform heating of the material. In this case the stress waves are produced by the expansion at the free surfaces of the specimen relieving the thermally induced high pressure. The crossing of the waves produces tensile stresses and strains near the center of the specimen that may result in mid-plane spall. The stress-strain response of the material is different for the uniform heating and plate impact cases. This difference is the critical information needed to show that spallation in metals is best described by a criterion based on strain rather than stress. Spallation results for three metals, 6061-T6 aluminum, OFHC copper and alpha titanium, are presented in terms of the critical strain necessary to produce incipient fracture. Author
- Metallurgy and Metallography