Characterization of the shock response of heterogenous polymer foams using multi-point PDV measurements

SX358 is a cross-linked polydimethylsiloxane (PDMS) that can be synthesized in a range of densities (0-65% porous). When porous, it is a stochastic, open cell heterogenous foam with varying pore sizes (10-1000s µm). To model SX358, experimental data is needed to inform equation of state (EOS) models over the range of initial densities. Gas gun planar impact was used to measure high pressure, high temperature material response and shock compression with traditional configurations and diagnostics. The results vary widely, which we attribute to the heterogenous structure of the foam. The diagnostics may interrogate areas where the local density is less than (e.g., a large pore) or greater than the average density. To explore pore variability, we interrogated a large sample area with many velocimetry probes, and then combined the data to obtain an ‘average’ material response. As with past experiments the individual probes showed a varied response. When the data are combined, the ‘average’ response provides a better measure of the continuum response of the stochastic foam with a reduced uncertainty. Phase contrast imaging of the propagating shock front and velocimetry diagnostics with interrogation areas larger than the pore sizes are under investigation to better constrain the EOS.