Pulsed Speeds in Granular Material at Variable
Packing Fractions
Utah State University
On April 14th and 15th, 1997, an experiment from Utah State
University was flown aboard NASA's Microgravity Simulator KC-135 as part of
the first annual Student Reduced Gravity Flight Opportunities Program. The
purpose of this experiment was to measure the speed of a sound pulse as it
propagated through a chamber filled with glass beads. The results obtained
from this experiment represent a novel attempt to determine the
relationship between the speed of wave propagation, and packing density in
a microgravity granular system. Many studies have been carried out
previously to further our knowledge of the nature of solids, gases, and
liquids. In fact, we are quite used to classifying matter into these three
convenient groups. Granular materials, on the other hand, cut across the
boundaries that separate liquids from gases, and liquids. They behave in
ways totally different from those observed in other classifications of
matter. Much was learned about the propagation of sound through granular
materials from the experiment conducted in the 1997 Reduced Gravity
Program. The experiment also presented many new, and exciting questions
that remain unanswered. The pulse speeds in granular materials experiment
has been redesigned using the data obtained from 1997's flights, and the
objective of this years' flight is to more effectively research the
relationship between packing density, and the speed of wave propagation in
granular materials
