2023-04-05 08:00:00
Due to recent unprecedented innovations in computing power, data-driven methods like Machine Learning (ML) have risen in popularity in the field of solid mechanics. Specifically, ML models have been fit to material potential energy surfaces (PES) due to their ability to reach ab initio…
Hopkinson pressure bars can achieve the same mechanical pressures as falling-weight machines and have an additional advantage in that they represent a closed mechanical system that is relatively easily describable in quantitative terms. The compressive force incident on the sample can be expressed in…
During the VIPIR (Viscoplastic flow Ignition and Propagation Imaging of Reactions) experiment, the kinetic energy of falling weight is transferred into the sample resting on the anvil. The sample consisting of particles of explosive crystals experiences compaction and large scale plastic deformation, followed by…
Plastic-bonded explosive (PBX) 9502 is produced as a molding powder comprised of 95wt% 2,4,6-triamino-1,3,5-trinitrobenzene (TATB) and 5wt% Kel-F-800TM. Three-dimensional (3D) microstructures can be achieved by varying compaction and sintering approaches on the powder. However, studies have suggested that the PBX9502 3D microstructure and shock…
Raman thermometry (RT) provides an attractive route for measuring the dynamic temperatures of shocked materials given its high time resolution, optical coupling, and its exclusion of material-dependent parameters. In this work, we plan to couple two shock drive sources- laser driven flyer plates and…
When polycrystalline energetic materials are shocked, recompression and rarefaction waves form inside the material due to crystal anisotropy. These waves interact with one another and with material defects (e.g., grain boundaries and cracks), localizing temperature in regions known as hotspots. Hotspots increase the ignition…
While plastic deformation of high symmetry crystals, such as metallic crystals, is well-studied, plasticity in low symmetry molecular crystals received much less attention. We investigate the physical basis of plastic deformation in the energetic molecular crystal HMX. We use atomistic simulations to evaluate the…
The ignition threshold of an energetic material (EM) quantifies the macroscopic conditions for the onset of self-sustaining chemical reactions. The threshold is an important theoretical and practical measure of material attributes that relate to safety and reliability in response to a wide range of…
Non-shock mechanical loading can induce reaction of explosive materials, and may result in the failure of munitions to perform as intended in impact scenarios. To characterize the ability of Air Force explosive materials to successfully withstand impact conditions, the High Explosive Survivability Test (HEST)…
Predicting the initiation properties of explosives is challenging due to the complexities inherent in their chemical structure and thermomechanical properties, combined with variations in the testing conditions utilized for measuring reaction ignition and propagation. In this presentation, we will discuss techniques for ranking explosive…
