Additively Manufactured Materials

Additive manufacturing introduces heterogeneities at the macro-scale, such as periodic and aperiodic voids and hierarchical layers, as well as particle aggregation and micro-voids on the meso-scale. These heterogeneities affect the shock compression response and influence the sensitivity of energetic materials. In order to use additive manufacturing to produce energetic and structural materials subjected to extreme environments, the role of process-inherent heterogeneities on the shock compression response needs to be investigated.

In the present work, additively manufactured mock energetic materials (mock-AMEMs) fabricated using direct write extrusion are investigated to study the role of AM process-inherent heterogeneities on their shock compression response. Additionally, bimetallic layered structures (BLS) fabricated using Selective Laser Melting and Electron Beam Freeform Fabrication are investigated for the role of the heterogeneous interface and microstructure on dynamic mechanical properties. Samples obtained from sections cut from AM fabricated blocks of mock-AMEMs and BLS are shock-compressed using gas gun plate-impact and spall experiments with Photon Doppler Velocimetry used to measure shock and particle velocities, and 1-D photonic crystal multilayer optomechanical sensors to measure spectral shifts associated with shock pressure. The measured PDV particle velocity profiles and pressure distributions obtained from spectral changes are correlated to deduce the role of heterogeneities.

Figure 1. Streak image using optical microcavity as opto-mechanical pressure sensor.