The behaviour of the polymer polyether ether ketone (PEEK) has been investigated under conditions of one-dimensional shock loading. This has involved measurement of the Hugoniot in terms of stress, shock velocity and particle velocity, and measurements of the lateral stress, which have been used to determine the shear strength, and its variation with shock stress. Analysis of the relationship between shock velocity and particle velocity shows a simple linear response, in common with many other materials. Shear strength has also been shown to increase with shock stress, with a break in slope at ca 1.0 GPa. Below this stress, the material appears to behave in a simple elastic manner, which suggests a Hugoniot elastic limit of 1 GPa. Shear strength has also been observed to increase significantly behind the shock front both above and below 1 GPa. This behaviour has been observed in other polymeric materials, where it was suggested that these materials were responding by a viscoplastic mechanism.
We present a series of experiments on the response of additive manufactured (AM) tantalum to dynamic loading, specifically the spall strength. Rectangular plates of AM tantalum were produced, with subsequent characterization revealing a highly anisotropic microstructure. Samples were taken from these plates to investigate the effect of anisotropy on the spall strength: the resistance to high strain-rate tensile damage. A conventional, wrought tantalum sample, possessing an equiaxed microstructure, was also tested to serve as a control. Shock loading was performed via light gas-gun flyer-plate impact experiments, with laser velocimetry on the rear of the samples to record the shock wave profiles and soft-recovery techniques to allow post-mortem analysis. In general, the AM samples were found to have a higher Hugoniot elastic limit, the dynamic yield strength under shock loading, while having a reduced spall strength, when compared to the wrought tantalum samples.
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