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Commercial manganin gauges were calibrated in a series of plane shock wave experiments. The calibration curve obtained is linear in the O-1.5-GPa range and curves for higher stresses (1.5-18.1 G Pa). The linear portion is attributed to the elastic behavior of the gauge. This was confirmed by experiments which included rarefactions from free surfaces. The onset of hysteresis was found to be at 1.5 GPa. The experiments demonstrated that the gauge's response does not depend on the target material in which the gauge is embedded. Also the thickness of the insulating layer which surrounds the gauge does not have any influence on its relative resistance changes.

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We present an analytical model for the calibration of lateral piezoresistance stress gauges in shock-wave experiments. This calibration is based on our experimental data with transverse Manganin gauges in shock-loaded polymethylmethacrylate targets. The experiments included lateral stress measurements under shock loading in the 1–30-kbar range and under complete unloading from stresses in the 5–9-kbar range. These unloading measurements resulted in a negative resistance change for the transverse Manganin gauge which implies that a hydrodynamic tension exists in it. The validity of our analytical calibration is demonstrated by comparing measured and predicted lateral stresses in glass targets.

The importance of understanding the variation of shear strength with pressure in the formulation of constitutive models has long been recognized. Previously, this had been deduced by measurements of the offset of the Hugoniot curve for a material from the calculated hydrostat. In recent papers, a direct measurement technique has been suggested in which both principal components of stress are measured using piezoresistive gauges. The reduction of the data collected from transverse stress gauges has attracted some debate and is reviewed here. In particular, the stress and strain states experienced by the gauge must be considered. The hardening of the gauge with longitudinal stress or pressure was investigated. Examples from experiments in metals and ceramics are given. The effect of gauge geometry was assessed and results show that the measured stresses from either gauge were within 0.5% of each other when subjected to identical impact conditions. An investigation was also performed on the effect of insulation thickness around the gauge and again no effect on the measured stress was found.

Glass bars and plates were subjected to impact loading. Failure waves were observed to propagate behind the compression waves. Material traversed by the failure wave suffers total loss of tensile strength and substantial drop in shear strength. Failure wave propagation velocities exceed the maximum crack propagation speed, but are not constant. In bars, failure wave speed range from 2.3 to 5.2 mm/μs, increasing with increasing impact velocity; in plates, the wave speed is about 2 mm/μs. The failure is ‘‘explosive’’ in nature, leading to radial expansion in bars and an increase in mean stress in plates.