Deformation around cavities from compressive loads

A test for survivability that has been applied to various scenarios involves compressively loading a confined cylindrical explosive sample to 100 MPa or higher levels in timeframes of 100 mus to 5 ms. There is a cylindrical cavity, either in the end of the sample next to the piston applying pressure or in the piston. The reaction threshold is obtained by varying the location of the cavity and its size as a function of loading rate. Axial stress is measured to confirm loading conditions and to provide time and pressure from reaction buildup, if any. Most recently, piston displacement is being measured for verifying the rate of cavity collapse calculated with LS-DYNA. Initial measurements were made on Teflon, for which there are reported Hopkinson bar data and a constitutive relation for high strain rate deformation. Model calculations for the stress-strain field in the deforming sample are an initial step toward predicting the onset of reaction in explosive samples.