Full correction of first-mode Pochammer–Chree dispersion effects in experimental pressure bar signals

Abstract

Frequency domain analysis of dispersed strain signals in pressure bars has been an active area of study for many years. Over the last two decades, methods have been developed for the correction of dispersed signals, by adjustment of the phase angles of the Fourier components of the signal. Recent work has shown that, theoretically, dispersion correction should be significantly improved by the application of additional correction factors to the amplitude of the Fourier components. This paper describes a study using experimental and related numerical work to further test these proposals.

Effect of Moisture Content on High Strain Rate Compressibility and Particle Breakage in Loose Sand

“…Strain data was recorded using semiconductor strain gauges and a TiePie Handyscope oscilloscope as described by Barr et al [5]. Axial stresses were calculated using a frequency-domain dispersion correction algorithm using the stresses from both pressure bars, and so represent the mean axial stress in the specimen [9,10].…”

A review of Pochhammer–Chree dispersion in the Hopkinson bar

“…In addition to the traditional phase shift correction, the magnitude of each frequency component need only be multiplied by the corresponding values of M 1 and M 2 to achieve full amplitude and phase correction. The method was verified numerically in the original paper, and later experimentally validated (Tyas and Pope, 2005).…”

On backward dispersion correction of Hopkinson pressure bar signals

“…A similar approach was presented more recently by Merle & Zhao [17]. Both Safford [14] and Tyas & Pope [18] demonstrated that the addition of this amplitude modification could lead to significant improvements in the accuracy of frequency domain dispersion correction when the aim was to recreate the loading on the impact face of a single HPB. An important consequence of these investigations is to highlight an issue that was very much apparent to Davies, but which has received little subsequent attention.…”