11 - Energy analyses in Kolsky bar experiments

Abstract

The Kolsky bar technique is based on one-dimensional stress wave propagation theory where mass and momentum are conserved such that force and displacement of a specimen are measured to obtain the stress-strain response of a material. Energy analysis in Kolsky bar experiments has not been systematically investigated despite potential insights into how materials dissipate or absorb energy during impact events. In this chapter, energy analysis in methods are presented in both the time and frequency domains, using a NiTi shape memory alloy as an example. Energy dissipation ratio is a useful means of quantifying the energy absorption capability of a material in the time domain. Energy analysis in the frequency domain provides additional information about how energy is distributed over a range of frequencies, which can inform better shock mitigation design. Interpretation of energy analysis in both domains is discussed for PMDI foam and TufFoam, silicone foam and rubber, as examples. The analysis techniques are used to investigate dissipation through a threaded joint interface as an example, though the analysis method is general and could be extended to any interface.