THE MEASUREMENT OF SPECIMEN SURFACE-TEMPERATURE IN HIGH-SPEED TENSIONAND TORSION TESTS

A radiometric technique has been developed capable of measuring specim en surface temperatures as low as 25 degrees C with a time resolution of similar to 1 mu s. The application of this technique to SHPB tests at strain rates of the order of 1000/s in both tension and torsion is described. In the torsion test results are obtained both during unifor m deformation, using a single element radiometer, and during localised deformation and the onset of fracture, using a 12-element radiometer. In the tension test the same 12-element radiometer was used to obtain the surface temperature distribution along each half of the broken sp ecimen immediately after fracture. The proportion of work converted to heat, beta, has been calculated using the temperature data from torsi on tests and was found to vary with increasing plastic strain from app roximately 0.2 to approaching 0.7. (C) 1998 Elsevier Science Ltd. All rights reserved.