Carbon resistor gauges for measuring shock and detonation pressures. I. Principles of functioning and calibration

Abstract

The state of the art relative to the measurement of shock and detonation pressures of the magnitude generaled by condensed high explosives is reviewed. Carbon resistors have been shown to provide a relatively inexpensive and direct method for such measurements, provided adequate calibration data are available. The gauge is fabricated by heat‐sealing the carbon resistor (470 Ω, 0.125 W) into a suitable plastic material such as polystyrene; when subjected to a strong shock wave, the gauge undergoes compression and the conductivity increases in proprtion to the magnitude of the pressure. The present investigation was concerned with the experimental derivation of calibration equations relating the pressure (in gigapascal) as a function of the conductivity change ΔG (in siemens). The point of inflaction occurring at approximately 2.36 GPa, corresponding to 0.02082 S, is in agreement with previous observations in the literature. Additional experiments are being planned to resolve a problem concerning oscillatory ringing in the gauge voltage records.

More on commercial carbon resistors as low pressure gauges

“…We do not recommend the use of these gauges for triangular pressure pulses with a rise and fall times of less than 0.5 ms. Clearly, more work has to be done to fully characterize the resistive hysteresis of these resistors. 1.77 g/cm 3 2.21 g/cm 3 Fig. 11.…”

“…Their high piezoresistive response, especially in the low pressure range of 0-2 GPa, and their simple and robust nature, make them ideal for both inert and reactive environments (see [2][3][4][5][6][7][8]). On the other hand, their relatively large dimensions result in high response times under shock loading, as compared with foil gauges which are commonly used in this field (manganin, ytterbium or foil carbon gauges).…”

Review of experimental techniques for high rate deformation and shock studies

“…Manganin fits all of these requirements but ytterbium [166,167] and carbon [168,169] are used in low stress regimes and in some explosive work [170] even though they do not meet several of the requirements listed above. Piezoelectric gauges have been used for many years and a wealth of literature exists on their polarisation under shock.…”

Thermal cook-off of an HMX based explosive: Pressure gauge experiments and modeling

“…Carbon resistor gauges have been successfully used in two-dimensional shock wave experiments where time resolution was sacrificed for survival of the gauge. [1][2][3][4] The constant current power supply for the carbon resistor gauges were always on passing about 18 mA through the 470 ohm resistors. The constant current pulse power supply for the manganin gauges was the Dynasen CK2-50/0.050-300, driving the gauge with a constant current of 50A.…”