April 3, 2023
Email office@phys.ksu.edu for the Zoom address
Abstract
Meta-structures are artificially engineered structures designed to exhibit properties not found in conventional materials. By careful design, one can obtain unprecedented control over various physical properties. Examples in mechanics includes structures having unique static and dynamic properties like negative Poisson’s ratio, zero shear modulus and non-reciprocal wave propagation.
Waveguides transporting energy and information are widely used in bulk and surface acoustic wave devices. They have stringent requirements of a dispersion bandgap and suffer from losses due to localization and scattering at defects or imperfections. In this talk, I will illustrate how these limitations can be overcome by a new class of symmetry protected meta-structures. Inspired by recent developments in topological physics, such meta-structures guarantee wave phenomena along an interface or boundary, immune to the presence of structural defects. I will present two examples of different classes of such meta-structures. The first example will show a general design paradigm to localize elastic wave energy in a structure at a desired frequency, while the second example will illustrate wave guiding along a channel in structures without any frequency bandgaps. Such waveguides have potential applications in acoustic signal processing, non-destructive evaluation and vibration isolation.
Brief Bio:Raj Kumar Pal received his bachelor’s degree in mechanical engineering from the National Institute of Technology, Trichy, India, followed by his master’s degree in the same field from the Indian Institute of Science, Bangalore, India. He then worked in industry for a year before starting doctoral graduate studies at the University of Illinois, Urbana Champaign. He earned a Ph.D. in Theoretical and Applied Mechanics, followed by postdoctoral appointments in the School of Aerospace Engineering, Georgia Institute of Technology, and in the mechanical and civil engineering department at the California Institute of Technology. Since 2019, he is an Assistant Professor in the mechanical and nuclear engineering department at Kansas State University. He works broadly at the intersection of solid mechanics and dynamics, investigating wave propagation phenomena with the goal of novel engineering applications.