X-ray phase contrast imaging of the shock response of an additively manufactured high solids loaded polymer composite

The performance of additively manufactured (AM) composites subjected to dynamic loading significantly depends on their micro- and meso-scale structures. The versatility offered by AM opens new ways to control performance via design of structure. AM composites have a wide range of process-inherent heterogeneities with a hierarchy of length scales such as non-uniform constituent distribution, interfaces, and porosity. In this work, temporally- and spatially-resolved measurements of macro-, micro-, and meso-scale heterogeneities were performed to investigate the shock response of an AM-fabricated high-solids-loaded polymer composite. Samples with pre-identified heterogeneities in the form of pores were impacted in different orientations relative to the print direction of the filaments. X-ray phase contrast imaging (PCI) was used to study the void collapse process and determine the shock and particle velocities upon arrival of shock wave front(s) via feature tracking. Photon Doppler velocimetry (PDV) was simultaneously used to measure the sample free surface velocity to determine the effects of local directional porosity on the equation of state, which in previous work was found to be independent of orientation effects in a similar material with a more uniform porosity distribution.