Electrical Response of a Bimetallic Junction to Shock Compression.
Final rept. 1 Nov 76-31 Dec 77,
WASHINGTON STATE UNIV PULLMAN SHOCK DYNAMICS LAB
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The electrical response of a copper-constantan junction to shock compression has been studied over a pressure range from 145 kbars to 360 kbars. Four possible sources of anomalous response were found electrical noise due to circuit closure at impact, shock demagnetization of a ferromagnetic material, high local temperature at the junction interface due to shock compression of a surface damage layer, and two-dimensional flow in the pressurized region due to pressure relief from the edges. Using a diffusion welded junction the emf measured is within 20 of the predicted emf based on normal thermocouple response to shock compression temperatures. In a geometry in which a guard ring was used to maintain the pressure behind the shock front, the observed voltage-time profile was a step with constant plateau. In a similar configuration where radial pressure relief was allowed behind the shock front, the initial step, which compares directly in amplitude to the above results, is followed by a marked positive ramping. This ramping was directly correlated with the two-dimensional flow due to radial pressure relief. The results indicate that any fundamental anomaly which exists for one-dimensional strain is less than 10-20 of the observed signals in the pressure range studied. Author
- Test Facilities, Equipment and Methods
- Electricity and Magnetism