Understanding the Dynamics of Periodic Planar Microstructures Responding to Colliding Micro-Particles

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Speeding airborne particles often result in severe physical erosion damage in aircraft, for example damage to jet engine turbine blades caused by ice or sand particles. This award supports research to understand the mechanics of collisions of high-speed particles on surfaces. Controlled collisions of rigid microparticles against surfaces with precisely manufactured microstructures will be conducted at various speeds and angles. 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. Modeling the ordered surface structures as planar metamaterials wil further contribute to the fundamental understanding of these interactions. The impact of this research has the potential to facilitate the development of novel industrial processes, such as particle sorting and selection, in industrial and public health sectors.Implementing functional microscopic textures in soft materials has shown exceptional adhesion and friction properties, as evidenced by the gripping abilities of Gecko feet and bio-inspired synthetic adhesives. This ballistic mechanical metamaterials 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). Furthermore, the researched mechanical metamaterials based on rationally designed planar viscoelastic microstructures, which serve as 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. This 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 researched mechanical metamaterials capable of manipulating the scattering cross-section of the incoming microparticles will extend the knowledge of the transient rheological and tribological behaviors of deformable solid materials and structures when subjected to ultrahigh-strain-rate mechanical stimuli.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.