Experimental study of the development of plastic solitary waves in one-dimensional granular media

In this work, a modified split Hopkinson pressure bar (SHPB) is used to impact one-dimensional granular chain of spheres. These homogeneous chains used here comprise of brass, aluminum, or stainless steel spherical beads, ranging from a single sphere to a chain of fourteen, and are of interest because of their unique wave propagation characteristics, as seen in earlier efforts. Loading magnitudes spanning from 9 kN to 40 kN – considerably higher than most previous works on these systems which have been conducted in the elastic regime – cause the granular chains to deform plastically. These conditions allow for solitary waves, which propagate in the one-dimensional array of elastic spheres, to be studied in the plastic regime. The propagating pulse assumes a distinctive shape after travelling through five beads, and can consequently be realized as a plastic solitary wave. The wave speed of this pulse was seen to depend on maximum force, as in the elastic as, although it was measured to be less than the elastic wave speed. In addition, the plastic velocity varied with the 1/9th power instead of the 1/6th power for the elastic speed. For the case of brass, the plastic wave propagates at 50% to 80% the speed of the elastic wave, depending on whether the incident or transmitted force is compared. It was found that there is also decreasing plasticity along the chain length except at the end beads in contact with the SHPB, which rebounds into the bar and are hit again. This research is the first to investigate in detail the development and evolution of a plastic solitary wave and will form the basis of future work in this area.

Name thesis:degree_name

M.S.

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Aerospace Engineering

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2011

Author dc:creator

• On, Tommy

Contributors dc:contributor

• Lambros, John

• Kolsy bar
• split Hopkinson pressure bar (SHPB)
• granular media
• granular chain
• solitary wave
• plastic wave
• plasticity

Statement dc:rights

• Copyright 2011 Tommy On

Language dc:language

en

Handle dc:identifier

http://hdl.handle.net/2142/26118

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/26118