Finite element investigation into the torsion test in the range of large strains and deformations

Torsion tests with thin-walled tubular, solid cylindrical and Lindholm-type tubular specimens were simulated using the finite element code ABAQUS, in the range of large strains and deformations. The results showed that for th in-walled tubular and solid cylindrical specimens the radii of the specimen s almost remained straight during torsion; for Lindholm-type tubular specim ens the twist angle of the cross-section at the two ends of the gauge secti on did not stay constant, due to the change of the specimen geometry (i.e. the end effect). A correction which considers the end effect should therefo re be introduced when the stress-strain relationship is characterized. Comp ared with the stress-strain relationship obtained previously from experimen t, a distinct difference was noted when conventional formulae were used to convert the torque and twist angle into the shear stress and shear strain. Further, the influence of axial constraint conditions at the two ends of th e specimen was examined; the results showed that axial strains and stresses had no significant influence on the definition of the shear stress-shear s train relation, and hence these can be neglected when the stress-strain rel ationship is characterized.