Shear and Axial Stress Response Under Fixed-End Forward/Reverse Torsion Loading of OFHC Copper

Torsion tests are conducted under fixed-end axial constraint conditions on thin tubular OFHC copper specimens. After a large shear strain of 2.2 in the forward direction, the specimen is twisted back to zero shear strain. From the tests, shear and axial stresses are obtained as a function of shear strain. These stress responses are also obtained from the Taylor-type polycrystal analysis with simple shear boundary conditions. Single-crystal constitutive parameters in the polycrystal analysis are obtained from uniaxial compressive tests conducted for large strains. Experimental and predicted torsion test results are compared. The Taylor method predicts the experimental shear stress response reasonably well under simple shear boundary conditions. Most of the salient features of the experimental axial stress response are captured by the Taylor prediction.