Evaluation of the Deformation Behavior of Nylon Materials Used in Ballistic Applications
BATTELLE PACIFIC NORTHWEST LABS RICHLAND WA
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Extruded and centrifugally cast nylon, representative of current projectile obturator band materials, were tested in compression at static and dynamic loading rates. The high strain rates associated with the dynamic compression test 2600 in.in.min resulted in significantly higher yield and compressive strengths, but only a minimal 8 increase in elastic modulus. Elastic constants for both materials were measured using the ultrasonic pulse- echo method, and the results show good agreement with mechanical test values. However, the experimentally determined elastic modulus values for both materials were found to be considerably higher than published book values. The effects of an elevated confining pressure on compressive deformation behavior were evaluated using a compressive load frame equipped with a hydrostatic fluid chamber. Although test results obtained at a confining pressure of 7000 psi indicate that the extruded nylon yield behavior approaches that predicted by Von Mises yield criterion, improvements in displacement instrumentation should be necessary before these data could be compared directly with other mechanical test results. It is concluded that a dynamic compression test in which the specimen is exposed to a hydrostatic confining pressure would be require to fully simulate the deformation response of obturator materials under ballistic launch conditions.