Impact induced solitary wave propagation through a woodpile structure

Abstract

In this paper, we investigate solitary wave propagation through a one-dimensional woodpile structure excited by low and high velocity impact. Woodpile structures are a sub-class of granular metamaterial, which supports propagation of nonlinear waves. Hertz contact law governs the behavior of the solitary wave propagation through the granular media. Towards an experimental study, a woodpile structure was fabricated by orthogonally stacking cylindrical rods. A shock tube facility has been developed to launch an impactor on the woodpile structure at a velocity of 30 m s −1 . Embedded granular chain sensors were fabricated to study the behavior of the solitary wave. The impact induced stress wave is studied to investigate solitary wave parameters, i.e. contact force, contact time, and solitary wave velocity. With the aid of the experimental setup, numerical simulations, and a theoretical solution based on the long wavelength approximation, formation of the solitary wave in the woodpile structure is validated to a reasonable degree of accuracy. The nondispersive and compact supported solitary waves traveling at sonic wave velocity offer unique properties that could be leveraged for application in nondestructive testing and structural health monitoring.

Review: Wave propagation in granular metamaterials

“…Thus the properties of particles and their contact interactions dominantly affect the mechanism of wave propagation. To understand the wave dynamics in granular structures, extensive studies have been performed in the setting of granular crystals, which are defined as closely packed periodic arrays of particles such as sphere, ellipsoid [15], cylinder [4,[16][17][18][19][20][21][22][23][24] and their combinations [25][26][27]. Also, various materials have been tested ranging from metals to polymers.…”

Demonstration of accelerating and decelerating nonlinear impulse waves in functionally graded granular chains

“…In linear regimes, these have been used for creating tunable bandgaps [22][23][24], topological defects [25], a mechanical non-reciprocal device [26,27] and Wannier-Stark ladders [28]. In addition, these systems have been used to manipulate strongly nonlinear impulse waves [21,[29][30][31], along with possible extensions to three dimensions (3D) [32].…”

Extreme control of impulse transmission by cylinder-based nonlinear phononic crystals

“…These have several unique features, including -but not limited to -the control of contact stiffness based on the stacking angles of cylinders (Khatri et al, 2012), and the utilization of cylinder lengths to induce local resonance effects due to bending (Kim and Yang, 2014;Kim et al, 2015a,b). Consequently, such systems can support a wide range of wave tailoring functionality, encompassing from filtering linear elastic waves by the formation of frequency band-gaps (Kim and Yang, 2014;Li et al, 2012;Meidani et al, 2015;Chaunsali et al, 2016) to manipulating highly nonlinear waves (Khatri et al, 2012;Kim et al, 2015a,b;Kore et al, 2016).…”