CARBON RESISTOR GAUGES FOR MEASURING SHOCK AND DETONATION PRESSURES .3. REVISED CALIBRATION DATA AND RELATIONSHIPS

For many years, carbon resistors have formed the basis for measurement of shock and detonation pressures associated with condensed explosives. The gauge is fabricated by heat-sealing the resistor into a plastic material such as polystyrene. When subjected to a strong shock wave, the resistance decreases, and the resulting increase in conductance is a function of the magnitude of the pressure. The present investigation was concerned with the experimental derivation of revised calibration equations, which was necessitated by the need to incorporate a terminating resistor into the gauge circuitry. The use of this resistor decreased the effect of standing waves and eliminated oscillatory ringing in the recorded signal. Typical records over a wide range of pressures are presented. An error analysis of the recorded data showed that the uncertainty in the measured pressure was of the same order of magnitude as the uncertainty in the interpretation of the recorded voltage from which the conductance was computed. An extensive discussion of the relevancy of the experimental data is presented, and the need for additional calibration experiments is stressed.