Manipulating Elastic Wave Propagation in Non-Linear Flexible Materials via External Stimuli

Pavel Galich
Work towards PhD Degree under the supervision of Asst. Prof. Stephan Rudykh
Department of Aerospace Engineering
Technion – Israel Institute of Technology

Ranging from the aerospace to the health industries, understanding of wave propagation phenomenon in solids is pivotal to a large number of practical applications, e.g., reduction or elimination of undesirable noise and vibrations in aerospace structures, nondestructive material testing, or noninvasive medical diagnostic procedures. Although wave propagation in continuum media has been investigated extensively in past decades, there is still a big venue for research. For example, the ability of flexible materials to sustain large deformations opens rich prospects for manipulating elastic wave characteristics by deformation. Moreover, elastic waves can be tuned through designing micro- or macro-structures, which can be further actively controlled by external stimuli, such as mechanical loading, electric or magnetic fields. However, before switching to complex architectured materials undergoing large deformations, we first need to understand how large deformations affect relatively simple isotropic and more complex anisotropic materials.

In this talk, we will start with the discussion of the acoustic properties of the relatively simple initially isotropic non-linear materials and proceed with the periodic layered and fiber composites made of these materials. Firstly, we will elaborate on the influence of the deformation induced stiffening (intrinsic feature of most soft materials) on the propagation of small-amplitude elastic plane waves. Secondly, we will illustrate that electroelastic isotropic materials (i.e. dielectric elastomers) can be utilized to achieve acoustic functionalities such as decoupling of pressure and shear waves by application of an electric field. Thirdly, we will analyse wave propagation in non-linear elastic and electroelastic laminates. In particular, we will present the long wave estimates of the phase and group velocities for the waves propagating in the laminates subject to external mechanical or electrical stimuli. Moreover, we will introduce the material compositions and loading conditions producing wide complete band gaps (frequency ranges where neither pressure nor shear waves can propagate) at low frequency ranges. Finally, we will discuss the anisotropy of elastic wave propagation in finitely deformed fiber composites (FCs) of different periodicity. Specifically, we will investigate the influence of fiber arrangements on shear wave propagation in these FCs. Additionally, we will show how shear waves propagating along fibers relate to the elastic instabilities in FCs and reveal how fiber periodicity influences elastic instabilities in FCs.

The talk will be given in English

Wed, 11-04-2018, 16:30 (Gathering at 16:00)

Classroom 165, ground floor, Library, Aerospace Eng.

Light refreshments will be served before the lecture

Manipulating Elastic Wave Propagation in Non-Linear Flexible Materials via External Stimuli