MIE’s Lee and Liu Obtain Major NSF Grant to Explore Ballistic Metamaterials Steering Fast-Moving Microparticles

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Jae-Hwang Lee and T. Leo Liu

Associate Professor Jae-Hwang Lee (principal investigator) and Assistant Professor T. Leo Liu (co-principal investigator) of the Mechanical and Industrial Engineering (MIE) Department are collaborating on a momentous National Science Foundation (NSF) award of $517,000 to investigate the dynamics of planar microstructures responding to colliding microparticles. The three-year grant will start in September of 2023.

According to the NSF abstract, “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 [caused] by high-speed particles have been understood as a challenge to overcome.”

However, as the two MIE researchers explain about their proposed research for the NSF, they are studying these extreme collisions of hard particles as a groundbreaking new tool to explore fundamental science and many applications.

As the researchers describe the work they will conduct in their NSF proposal, “Rigid microparticles will be controlled to collide against a systematically (micro- and nano-) structured surface at various speeds. Energy exchanges between the speeding particles and the periodic (surface) structures will be observed with ultrafast imaging. The mechanical-interaction-characteristics research, varying with the particle’s energy and momentum, will extend the scope of traditional spectroscopy to mechanics.”

But all that basic research is far from the extent of this far-reaching NSF proposal. “In another aspect,” as Lee and Liu say, “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, as Lee and Liu state, “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.”

Beyond those applications, Lee and Liu expect the proposed mechanical meta-surfaces – based on rationally designed, two-dimensional, viscoelastic microstructures – to demonstrate various unexplored nonlinear dynamic phenomena, such as energy absorption resonance, anti-Stokes scattering, and geometrical quantization in the mechanical system.

As Lee and Liu conclude, “Thus, the research project will advance the fundamental understanding of how mechanical meta-surfaces dynamically create interfacial responses originating from viscoelasticity, geometrical-phase transformation, and the evolution of microstructural adhesion.”

As Lee says about his Nano-Engineering Research Laboratory, “Our lab has a unique experimental method, known as Laser Induced Projectile Impact Test (LIPIT), for investigating the high-strain-rate and high-strain-dynamic characteristics of materials primarily for additive manufacturing and protective materials. Using the LIPIT, we are quantitatively studying the structure-property relationship of nano- and micro-structured materials under extreme conditions and attempting to extend the use of LIPIT to soft materials, including fluids and biological substances.”

Liu says that his lab specializes in developing advanced microelectromechanical systems (MEMS) fabrication techniques to create unique material interfaces with micro- and nano-scale features. These techniques have enabled a wide range of interdisciplinary fundamental studies and engineering applications, including super-repellent surfaces, soft and stretchable electronics, microfluidics, heat transfer, and biomimetics.

(July 2023)