A Shear-Tension Specimen for Large Strain Testing

A new shear-tension specimen (STS) is designed, evaluated and tested quasi-statically and dynamically. The specimen consists of a long cylinder having an inclined gauge section created by two diametrically opposed semi-circular slots which are machined at 45° with respect to the longitudinal axis. The geometry imposes stress condition within the gauge section which correspond to a Lode parameter of ~ −0.5, between pure shear (0) and uniaxial tension (−1). It thus provides a wider span of loading conditions for a material. A thorough numerical study reveals that the stresses and strains within the gauge are rather uniform, and the average Mises stress and plastic strain on the mid-section of the gauge represent the material true stress–strain characteristics. The data reduction technique to determine the stresses and strains is presented. Quasi-static and dynamic tests at strain rate of 10⁴ 1/s were carried out on specimens made of 1020 cold-rolled steel. No necking or softening was observed with this specimen, and the fracture location was always well within the gauge. The obtained stress–strain curves and ductility were validated numerically. The STS is a new specimen to study the combined influence of tension and shear on the mechanical characteristics of a material.