Over the years for several demanding engineering applications such as armor, automobile body components, re-entry vehicles and hypersonic vehicles, materials such as ceramics and metallic alloys are preferred because of their excellent mechanical strength and durability. In such harsh applications, the materials typically experience high forces in a matter of few microseconds and the resultant strain rates could be of the order of 10³ to 10⁷ s⁻¹. The sudden increase in energy experienced by these materials due to such high strain rates is accommodated by unique deformation mechanisms such as dynamic recrystallization. Therefore, understanding the dynamic strength and failure behavior of the materials at such high strain rates is pivotal for better design and processing of materials for such extreme applications. In the macroscale (milli- to centi- meter scale) dynamic testing, the Kolsky bar and Split Hopkinson Pressure bar are the predominantly used experimental methods. But such techniques cannot be used to investigate the dynamic micro- and nano- scale material properties typically ascertained using nanoindentation and microcompression.

In this work, we developed instrumentation, methodology and protocols to extract the dynamic strength, flow stress and hardness of micro-/nano- scale materials at high strain rates using an in situ nanomechanical tester capable of indentation and microcompression. Using this state-of-the-art nanomechanical tester it is now possible to achieve constant strain rates of up to 100000 s⁻¹ in indentation and 10000 s⁻¹ in microcompression. In addition, the advanced electrical hardware such as piezoelectric sensors/actuators, gigahertz oscilloscopes and laser interferometer based calibrations necessary for acquiring high fidelity load-displacement data at such microsecond timescales and the challenges associated with data analysis will be discussed in detail. Finally, as a proof of concept, the results from nanoindentation experiments carried out on fused silica and nanocrystalline nickel and microcompression experiments on fused silica and silicon micropillars will be presented.