Mechanical Engineering seminar “Nonlinear mechanical metamaterials for stress wave manipulation”

Jinkyu Yang, an Assistant Professor in Aeronautics & Astronautics at University of Washington, Seattle, presents “Nonlinear mechanical metamaterials for stress wave manipulation.”

Recent advancement of acoustic/mechanical metamaterials opens new routes to achieving unique mechanical properties of material systems unprecedented in nature. While these metamaterials promise an enhanced degree of freedom in controlling their static and dynamic responses, previous studies focused mainly on the linear responses of the artificially fabricated metamaterials. In this presentation, I will talk about the novel wave dynamics and potential engineering applications of nonlinear mechanical metamaterials. Unlike conventional linear ones, these nonlinear metamaterials are capable of forming and supporting new types of nonlinear wave structures. First, I will talk about turbulence-like energy cascades of nonlinear stress waves propagating in woodpile mechanical metamaterials. These systems enable controllable manipulation and redistribution of stress waves over time and space domains, which can lead to the efficient attenuation of mechanical waves without resorting to material damping. Then, I will discuss the feasibility of using origami-based metamaterials for nonlinear wave mixing and sculpting effects. These origami-based metamaterials leverage the formation of nonlinear rarefaction waves, which are characterized by tensile wave fronts despite the application of compressive impact. While the studies in this presentation are built on the theoretical foundation of nonlinear wave dynamics and its numerical/experimental verifications via simple prototypes, the potential applications of these nonlinear mechanical metamaterials are abundant, ranging from energy harvesting devices and reconfigurable impact absorbers.

Jinkyu “JK” Yang is an Assistant Professor in Aeronautics & Astronautics at the University of Washington (UW). Before he joined UW in 2013, he was an Assistant Professor in Mechanical Engineering at the University of South Carolina (2011~2013) and was a postdoctoral research scholar at Caltech between (2009~2011). Dr. Yang also has industrial experience in product development as a senior engineer at Samsung Electronics between 2006 and 2009. Dr. Yang received masters and doctoral degrees in Aeronautics and Astronautics at Stanford University in 2001 and 2005, respectively. His research is directed towards developing advanced structures for aerospace, mechanical, and biomedical applications. To achieve this goal, he explores nonlinear dynamics of novel engineered material systems, e.g., metamaterials and phononic crystals.