A method for the simultaneous derivation of tensile and compressive behaviour of materials under Bauschinger effect using bend tests

Some materials exhibit Bauschinger effect as a consequence of strain hardening. The effect leads to asymmetric tensile and compressive stress-strain behaviour. If the hardening behaviour in either tension or compression is known, combined isotropic /kinematic hardening rules can be used to estimate the hardening behaviour in the other. These rules are, however, only approximate empirical relationships that are derived from the analysis of separate tensile and compressive test results. This article presents a method for the simultaneous derivation of tensile and compressive stress-strain behaviour from bending tests only. The information required is strains at the top and bottom surfaces of beams and moment as load is incrementally applied. The derivation of the method is based on the application of tensile and moment equilibrium conditions. The proposed method is tested on theoretical data obtained from finite-element analysis and as well as on data from actual experimental testing. The agreement between the results obtained is very good.