elastic wave propagation

I have a few positions (funded by NSF, AFRL, and/or ARO) for MS or PhD (preferred) students at the University of Tennessee Space Institute (UTSI) and University of Tennessee Knoxville (UTK) in the following two topics:

1. Elastodynamic metamaterials: Characterization of dispersive constitutive equations and simulation of the material with overall properties in the time domain (TD), analysis of the effect of disorder and material nonlinearities (e.g. fracture) in their performance, etc.

In this paper, we study the dynamic flexural behaviour of a long bridge, modelled as an infinite periodic structure. The analysis is applied to the ‘Brabau’ bridge across the river Tirso in Italy. The approach reduces to a spectral problem leading to the analytical expression of the dispersion relation, which provides the ranges of frequencies for which waves do and do not propagate. The contributions of the bridge structural elements on the dispersive properties of the structure are investigated in detail.

For the first time, a design of a “deflecting elastic prism” is proposed and implemented for waves in a chiral medium. A novel model of an elastic lattice connected to a non-uniform system of gyroscopic spinners is designed to create a unidirectional wave pattern, which can be diverted by modifying the arrangement of the spinners within the medium.

A funded PhD position is open for summer or fall 2017 in the Mechanics and Dynamics Laboratory in the Department of Aerospace Engineering at Wichita State University. The research program will focus on the design and development of mechanical metamaterials, their application towards aerospace structures, and will involve a combination of analytical, numerical, and experimental methods. The candidate must have a MS in Aerospace or Mechanical Engineering and a strong background in structural mechanics and dynamics.

The paper presents a novel analysis of localisation and transmission properties of randomly-perturbed flexural systems. Attention is given to the study of propagation regimes and the connection with localised resonance modes in the context of Anderson's localisation. The analytical study is complemented with numerical simulations relevant to the design of efficient vibration isolation systems.

Eigenvalues, reflected and transmitted energy, localisation factors for the examined bi-coupled random system:

Recently we published a paper in Physical Review Applied. It can be downloaded from the link

 http://journals.aps.org/prapplied/abstract/10.1103/PhysRevApplied.3.064014

 Abstract of the article is below:

Hi everybody, I'm so interested in analysis of wave propagation in solid medias. and I've started by studying some books like "Ultrasonic wave propagation in solid media"(Rose). My question is about the importance of this analysis  (propagation of high frequency elastic waves) in the structures. I know that the major application is in the field of Nondestructive Testing(NDT). but I don't know if it is usefull in vibrational analysis of mechanical structures (elastic waves with frequencies around KHz or MHz). is this study important in "dynamic response analysis" of mechanical structures in some special kind of loading like impact? I'd be gratefull if you could introduce me some examples.