Visualisation of Wave Propagation in Impulse-Loaded Bars

Abstract

Various experimental techniques which can be used for the visualisation of stress waves are considered and their applicability to the study of wave propagation in bars is discussed. Some experimental results which were obtained by means of shadow photography are given. These were obtained with bars immersed in water and show the existence of precursor waves which travel with the velocity of propagation in an unbounded medium. A qualitative theory of the wave system is outlined and it is shown that the concept of group velocity in terms of the Pochhammer-Chree treatment leads to some difficulties in this problem.

A second investigation using a different method of visualisation, namely flash radiography is also described. This technique has here been used for studying the passage of intense plastic waves in rods.