CAREER: New Polarizations of Elastic Waves in Architected Materials

This Faculty Early Career Development (CAREER) grant will fund research that enables the design of dynamic systems to sustain targeted functionalities such as vibration mitigation, ultrasonic imaging, and thermal phononic manipulation, thereby promoting the progress of science, and advancing national prosperity and welfare. The project will build the analytical, computational, and experimental foundations for the knowledge associated with three novel polarizations of elastic waves: non-paraxial spins, tensorial plane waves, and knotted modes via a new family of architected mechanical metamaterials. These are brand-new wave polarizations that so far cannot exist in any materials, natural or man-made. These next-generation metamaterials are expected to have strong societal impacts, such as saving human lives, buildings, and bridges during earthquakes, as well as saving billions of dollars of medical costs via accurate diagnostics. This CAREER project integrates research and education to form innovative strategies for knowledge dissemination that showcase the societal benefits of the field of wave mechanics and metamaterials and spark interest among Native American students to pursue studies and careers in science and engineering. This research aims to exploit the unique possibilities inherent in mechanical metamaterials to realize wave phenomena that transcend the boundaries defined by the current scientific knowledge. These new metamaterials will support exotic polarizations that are not yet predicted by any theory or observed in any experiment. Specific targets include intrinsic spin angular momentum that is not paraxial to the propagation direction, tensorially polarized elastic plane waves that are analogous to the gravitational waves, and propagation of multi-frequency waves with generalized polarizations that are specified by mathematical knots. The overall goal is to find new horizons in metamaterials research while significantly expanding our tool sets in wave manipulation. This research has the potential to enable the complete and detailed tailoring of the mechanical/phononic transfer of information and energy. The expected outcomes will seed and fertilize a new research field of unconventional wave polarizations. 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.