Plastic Biaxial Stress-Strain Relations for Alcoa 24S-T Subjected to Variable-Stress Ratios

Joseph Marin, B. J. Kotalik
1950 Journal of applied mechanics  
Usually plastic biaxial stress-strain relations for metals have been determined for tests in which the ratios of the principal stresses have been maintained essentially constant. This paper presents biaxial plastic stress-strain relations for both constant and variable-stress ratios. The purpose of conducting the variable-stress-ratio tests is to attempt to prove whether the flow- or deformation-type theory is the correct theory for predicting plastic stress-strain relations. The paper also
more » ... s a comparison between the actual and theoretically predicted values of the biaxial yield, ultimate and fracture strengths, and the biaxial ductility. Various ratios of biaxial tensile stresses were investigated by subjecting tubular specimens to axial tension and internal pressure. The test results showed that the yield-strength values agree best with the distortion-energy theory. For the prediction of the plastic stress-strain relations the deformation-type theory was found to be in approximate agreement with the test results for both the constant- and variable-stress-ratio tests.
doi:10.1115/1.4010160 fatcat:q7nmwkvsk5fafjbqlh2tbt567q