Experimental mechanics at the extremes
High strain rate experiments
As one of the primary directions of our group, we develop specialized experiments to probe the high strain rate, high pressure response of materials. Currently established infrastructure allows us to study materials under compression, tension and torsion at quasi-static strain rates, and compression at strain rates on the order of 1000/s. We are in the process of developing a larger repertoire of dynamic compression, tension and torsional experiments using miniature Kolsky bars (achievable strain rates ~ 10^5/s). To investigate high pressure (and shock) response of materials we are designing experiments with the Laboratoire pour l'Utilisation des Lasers Intenses (LULI) to perform laser-driven dynamic compression. Future directions of the lab involve pressure-shear plate impact to systematically investigate the shear response of materials under high pressure dynamic compression. We develop electronic and optical instrumentation in house to measure material response under complex stress states and short time scales.
Probing elastic waves in materials and structures
Synopsis...
Coupling mechanics and multi-physics in experiments
During high strain rate loading, the thermodynamic state of a material deviates from isothermal towards nearly adiabatic. Hence, temperature rise during dynamic loading can seldom be ignored, especially when considering the micro-mechanics of deformation. Another major focus area of the group is in the dynamic response of multi-functional e.g., ferroelectric, ferromagnetic materials. These materials exhibit direct multi-physical coupling between thermo-mechanical and electro-magnetic fields, due to local structural transformations at the atomic scale.
We are developing novel experiments and instrumentation that enable in-situ control and measurement of mechanical, thermal, electrical and magnetic fields. Such experiments are crucial towards understanding complex multi-physical coupling in materials, more so at short time scales and high pressures. We use these methods to understand domain wall kinetics in ferroelectric materials, phase transformations in ferromagnetic media, and plastic deformation in metallic systems.