Abstracts

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…

The strong and highly anisotropic influence of grain boundary (GB) character on the plasticity of crystalline materials motivates an overarching goal of developing a bicrystallography-sensitive GB model applicable across all misorientations, inclinations, and crystal systems. Here, we focus on the shear coupling factor of…

Helium bubbles impact mechanical properties of nuclear materials. An Fe-Ni-Cr-H-He potential has been developed to enable molecular dynamics simulations of helium bubble nucleation and growth. This is accomplished by addressing three challenging paradoxes: (a) helium forms tightly bound dimers and clusters in the lattice…

Reverse Monte Carlo (RMC) is a technique to interpret experimental diffraction data by applying the Metropolis Monte Carlo algorithm to derive an atomistic model that fits the data. This optimization method is inherently stochastic and underconstrained, so it tends to yield highly disordered and…

Machine learning (ML) interatomic potentials offer new opportunities to accurately simulate larger material systems for longer periods of time. In the past decade, a large number of ML potential models have been proposed, but the assessment of their reliability and the quality of the…