2025-04-09 09:00:00
Prolonged space travel is becoming an increasingly intriguing possibility but has many challenges across multiple scientific fields. The question that must be asked of every component within the spacecraft is whether the materials can provide the expected performance despite the harsh thermal and radiation…
The strength of Polymethyl Methacrylate (PMMA) depends on temperature and rate of loading (strain rate), according to published literature. PMMA becomes brittle at low temperatures, ductile at higher temperatures, and exhibits a brittle behavior at elevated strain rates from strain hardening. We are exploring…
Dynamic collapse of voids plays a key role in hot spot formation and the shock-to-detonation transition (SDT) in energetic materials. To better understand the dynamic material response which leads to hot spot formation, here we quantitatively characterize the kinematic fields around collapsing cylindrical holes…
Time-resolved, synchrotron X-ray diffraction methods coupled to gas and powder gun shock experiments are used to study twinning, detwinning, and melting in magnesium alloy AZ31B-H24. The X-ray diffraction data shows that when this cold-rolled polycrystalline metal is shock-compressed to ~9 GPa in the rolling…
Three-dimensional (3D) tomography using focused-ion beam (FIB) microscopy is a powerful technique to generate sub-micron resolution volumes that can expand upon the information acquired two-dimensionally with scanning electron microscopy (SEM). This is critical for contextualized phenomena that need to be captured in 3D to…
An experimental apparatus designed to measure the dynamic behavior of materials under strain rates around 10³ s⁻¹ and temperatures up to 800°C is developed in this study. The system builds upon the traditional Kolsky (split-Hopkinson pressure) bar setup, incorporating an external furnace to heat…
The specific energy absorption (Ep*) by a protective shield during projectile impacts depends on many factors, including material’s constitutive response, density, and layer thickness, deformation and failure mechanisms, and projectile’s shape, mass, and velocity. Laser-induced projectile impact test (LIPIT) allows testing sub-micron-thick materials with…
elaxation dynamics, as a key to understand glass formation and glassy properties, remains an elusive and challenging issue in condensed matter physics. In this presentation, I will introduce our recent development of in situ high-pressure synchrotron high-energy x-ray photon correlation spectroscopy, which enable us…
High-energy X-rays (HEX) above 60 keV are quite valuable, especially for partially or fully disordered materials, because they allow structural studies in both real and reciprocal space, while the moderate X-rays (e.g., 30 keV) can only be used to study the long-range periodic structure…
Tamrakar et al. conducted strain rate-dependent experiments in which a microdroplet of epoxy resin was bonded to a single glass fiber and then that bond was broken by mode II shear loading [1]. With that data, Tamrakar et al. used finite element modeling to…
