Solitary waves in the granular chain

We report the first experimental observation of impulse confinement and the disintegration of shock and solitary waves in one-dimensional strongly nonlinear composite granular materials. The chains consist of alternating ensembles of beads with high and low elastic moduli (more than 2 orders of magnitude difference) of different masses. The trapped energy is contained within the "softer" sections of the composite chain and is slowly released in the form of weak, separated pulses over an extended period of time. This effect is enhanced by using a specific group assembly and precompression.

/pdf/energy-trapping-and-shock-disintegration-in-a-composite-2jwrli4h0x.pdf

Energy trapping and shock disintegration in a composite granular medium.

http://maeresearch.ucsd.edu/nesterenko/PUB_PDFS/A1/88,%20A%20I,%202002.pdf

Self-organization of shear bands in titanium and Ti–6Al–4V alloy

Phononic crystals (PCs) and metamaterials (MMs) can exhibit abnormal properties, even far beyond those found in nature, through artificial design of the topology or ordered structure of unit cells. This emerging class of materials has diverse application potentials in many fields. Recently, the concept of tunable PCs or MMs has been proposed to manipulate a variety of wave functions on demand. In this review, we survey recent developments in tunable and active PCs and MMs, including bandgap and bandgap engineering, anomalous behaviors of wave propagation, as well as tunable manipulation of waves based on different regulation mechanisms: tunable mechanical reconfiguration and materials with multifield coupling. We conclude by outlining future directions in the emerging field.

Tunable and Active Phononic Crystals and Metamaterials

Granular materials exhibit a strongly nonlinear behavior affecting the propagation of energy and information. Dynamically self-organized strongly nonlinear solitary waves are the main information carriers in granular chains. We report the first experimental observation of the dramatic change of solitary wave reflectivity from the interface of two granular media triggered by a magnetically induced precompression. It may be appropriate to name this phenomenon the "acoustic diode" effect. We explain this effect by the high gradient of particle velocity near the interface.

/pdf/anomalous-wave-reflection-at-the-interface-of-two-strongly-2vbydynm09.pdf

Anomalous wave reflection at the interface of two strongly nonlinear granular media.

Observation of a new type of solitary waves in a one-dimensional granular medium

The decay of soliton at the contact of two “acoustic vacuums”

Two deformation regimes, namely, quasi-static and dynamic ones, can occur in the process of shock wave deformation of granular powders. The dynamic regime is shown to be necessary for obtaining str...

A. N. Lazaridi

Papers

Observation of a new type of solitary waves in a one-dimensional granular medium

The decay of soliton at the contact of two “acoustic vacuums”

Regimes of shock-wave compaction of granular materials

Microstructure after heat treatment for explosive compacts made from granules of rapidly quenched titanium alloys

Shock-wave compaction of mechanically activated powder of the system Fe−Nd−B