Push it to the limit: Investigating the Material Response of Nano- and Micro-materials under Extreme Mechanical Environments

Abstract

High velocity impact phenomena range in scale from catastrophic events such as impact of aircraft and missiles into large infrastructures to impact of micron– and sub–micron–sized micrometeorite particles into spacecraft and satellites. Although, events of this nature are not a popular topic in the public community, they play a large role in the material development to meet the technological and protective needs of today. Materials with length scales in the nanometer range are known to exhibit superior mechanical properties as their unique structure-property relations are drastically different than many macroscopic materials, some examples include: graphene, carbon nanotubes, polymer nanocomposites, and gradient nano-grained metals. When utilized at the macroscale, the unique nanomaterial properties do not always translate due to impurities, defects and inherent flaws in the scaled-up bulk material. Additionally, certain materials may only exhibit unique properties during transformations requiring extremely high pressures. In this thesis, I employ a micro-ballistic impact test to study the very high strain rate behavior of one-dimensional (1-D) carbon nanotubes in a non-woven mat, two-dimensional (2-D) assemblies of polymer grafted nanoparticles, and three-dimensional (3-D) silver metallic micro-cubes, to understand the structure-property relations of these nanomaterials and micromaterials, with nanoscale features, at the nano- to microscale. The micro-ballistics technique will provide a better pathway for researchers to scale these materials to the macroscale with tailored properties for different applications, like fracture resistant coatings, impact mitigating protection systems, and reinforcement for large infrastructures.