Material Testing Method of Applying In-Plane CombinedTension-Compression Stresses to Sheet Specimen

Abstract

An experimental method of applying in-plane combined tension-compression stresses to a sheet specimen is proposed. Comb-shaped dies are specially designed for the tension-compression test and are installed into a biaxial stress-testing machine developed by one of the authors [Kuwabara and Ikeda: J. JSTP, 40-457 (1999), 145-149]. To check the usefulness of the testing apparatus proposed in this study, we carried out biaxial stress experiments using a high strength steel with a tensile strength of 440MPa, and detailed measurements were made of the plastic work contours as below and the directions of the incremental plastic strain vectors at different levels of work-hardening for linear stress paths in the second and fourth quadrants of the principal stress space, as well as in the first quadrant. We found that the measured work contours are similar in shape, and that the directions of the incremental plastic strain vectors remain almost constant at each constant stress ratio. The work contours and the directions of the incremental plastic strain vectors are in close agreement with those predicted using the Hosford or Yld2000-2d yield function.