The construction and calibration of an inexpensive PVDF stress gauge for fast pressure measurements

Commercial polyvinylidene difluoride (PVDF) piezoelectric film was used to produce an inexpensive stress sensor with good spatial accuracy to measure the stress state behind a shock wave. The PVDF gauge was found to respond within approximately 100 ns to fast-rising pulses. Since the gauge is piezoelectric no power supply or amplifier was required for the gauge. In order to measure fast signals the gauge was found to perform best in the current mode in which the derivative of the stress was measured; the signal was then numerically integrated. Signals were recorded on a fast (100 MS s^-1) storage oscilloscope. The gauges were calibrated against thin-foil manganin stress gauges to approximately 2%. An application in which the gauges were used to measure the response of an alumina to shock loading is described.