Ballistic Metasurface (NSF)

Understanding the dynamics of two-dimensional microstructures responding to colliding micro-particles

Speeding airborne particles result in severe physical erosion damage, as observed in the jet engine turbine blade’s damage caused by ice or sand particles. Thus, except for a few exceptions in engineering processes, such as shot blasting and sandblasting, the damage processes by high-speed particles have been understood as a challenge to overcome. However, the extreme collisions of hard particles are proposed as a new tool to explore fundamental science in the proposed research. Rigid microparticles will be controlled to collide against a systematically structured surface at various speeds. Energy exchanges between the speeding particles and the periodic structures will be observed with ultrafast imaging. The mechanical interaction characteristics varying with the particle’s energy and momentum will extend the scope of traditional spectroscopy to mechanics. In another aspect, the periodically structured surface can be understood as an artificially created two-dimensional material. Thus, the new material concept and phenomena explored in the research will help materials science education. Furthermore, the impact of the proposed research is not limited to fundamental science and education but facilitates the development of novel industrial processes such as particle sorting and selection in the industry and public health sectors.

Functional microscopic texturing of soft materials can create exceptional adhesion and friction properties, as observed in Gecko feet and bio-inspired synthetic adhesives. The proposed ballistic mechanical metasurface study will extend the scope of tribological characteristics of microstructured surfaces from the quasi-static (sub-second regime) to the high-strain-rate (sub-microsecond regime) regime. Furthermore, the proposed mechanical metasurfaces based on rationally designed two-dimensional viscoelastic microstructures, a collection of viscoelastic resonators, are expected to demonstrate various unexplored nonlinear dynamic phenomena, such as energy absorption resonance, anti-Stokes scattering, and geometrical quantization in the mechanical system. Thus, the research project will advance the fundamental understanding of how mechanical metasurfaces dynamically create interfacial responses originating from viscoelasticity, geometrical phase transformation, and the evolution of microstructural adhesion. Ultimately, the proposed mechanical metamaterials that can engineer the scattering cross-section of the influx of microparticles will extend the knowledge of the transient rheological and tribological responses of deformable solid materials and structures under ultrahigh-strain-rate mechanical stimuli.