An experimental-finite element analysis of the plane stress local torsion

The plane stress local torsion (PSLT) is an attractive method to strengthen the material in the areas of interest. A closed form solution of the problem is complex and an interpretation of the measured raw torque–twist data into the effective stress and strain is not straightforward. These hinder the optimization and control of the technique. In this study, the PSLT test was performed using Ti-IF steel specimens and their torque–twist response and radial distortion were compared with those obtained from an elastic–plastic model of the PSLT developed by the commercial finite element software, ABAQUS. The resultant microstructure in the samples as a result of large local shear strains and the extent of deformation were studied using SEM and a grid distortion technique, respectively. Mechanical property changes after the PSLT processing were characterized in samples of different geometry using a dedicated formulation based on the similarity theory. The micro shear punch tests allowed characterizing the gradient of the reinforcement in the radial direction of the samples.