NONCONTACTING STRAIN-MEASUREMENTS DURING TENSILE TESTS

The application of an innovative noncontacting Doppler laser extensome ter is presented, True axial strain has been measured during tensile t ests conducted on stainless-steel metal sheets over a range of strain rates (from 10(-4) to 10(2) 1/s) and temperatures (from -40 degrees C to 400 degrees C), The laser radiation scattered at the surface of the specimen is recorded during the duration of the experiment. The signa ls are then used to determine the evolution of the axial strain, which is subsequently combined with the load signal to construct the stress -strain curve for the material, Excellent agreement has been obtained between the total elongation predicted by the laser measurements and t he actual values measured from the specimens, This technique offers se veral advantages over traditional strain-measuring technologies.