MMAE Seminar by Alireza Amirkhizi: Stress Waves Interacting with Micro-Structured Media: Overall Response, Scattering, and Novel Applications

Armour College of Engineering’s Department of Mechanical, Materials, and Aerospace Engineering will welcome Alireza Amirkhizi, an associate professor of mechanical engineering at the University of Massachusetts, Lowell, on Wednesday, September 23, 2020, to present a lecture on "Stress Waves Interacting with Micro-Structured Media: Overall Response, Scattering, and Novel Applications."

Abstract:

It is not unexpected that periodic micro-structured media demonstrate behavior that are distinct from homogeneous media, especially when the length scale of the phenomena of interest is comparable to the periodicity of the medium. However, when the periodicity length scale is at least an order of magnitude smaller than that of the phenomenon of interest, one might seek to represent the response of such structures with overall constitutive laws of a fictitious homogenous medium. In these cases, especially when the overall observed response is not what one usually expects from natural or traditional engineering materials, the term metamaterials has been (over)used to signify such media. In this talk, we look at examples of dynamic mechanical metamaterials, with particular attention to stress wave propagation and scattering. Overall constitutive descriptions based on scattering and field averaging will be evaluated. More interestingly, some ideas for design of devices and media with desired response, effect of discretization on such design problem, and newer exciting potential applications of the micro-structured media in source localization will be presented.

Biography:

Alireza Amirkhizi is an associate professor of mechanical engineering at the University of Massachusetts, Lowell with focus on dynamic characterization of materials, composites, and structures. He was previously a research scientist at UC San Diego, where he also received his Ph.D. Amirkhizi’s research interests include conceptual and computational design, fabrication, and experimental characterization of low-frequency 3D printed mechanical metamaterials with focus on acoustic mitigation as well as high loadings and rates of deformation. His laboratory is equipped with a suite of material characterization facilities including gas guns and recovery split Hopkinson bars that are used for high strain-rate and impact characterization and can also be modified to allow for low frequency stress wave scattering measurements. Amirkhizi has also contributed extensively to the constitutive characterization of elastomeric polymers, foams, and polymer-based particulate composites in extreme conditions, including high strain-rate loadings, very high pressures, and very low temperatures. Additionally, he has worked on reliability of flexible-hybrid electronics with particular attention to characterization of multi-axial toughness at interfaces between rigid and soft films.