Effects of 2D misalignment on tensile results and corresponding correction methods to obtain the true stress–strain curve

In miniature horizontal-type in situ tensile devices, misalignments on the horizontal and vertical plane cause shearing and bending effects in the specimen and further lead to incorrect testing results of mechanical parameters. To investigate the effects of misalignment between the tensile axis and the specimen's geometrical axis on the testing parameters and obtain the true stress and strain relationship, two correction methods based on linear deformation and deflection curve deformation were proposed, and the effect laws of the horizontal deviation angle alpha and vertical deviation angle beta on mechanical parameters were analyzed. The feasibility of the proposed correction methods was verified with the help of a miniature device integrating a modified Arcan fixture. The establishment of alpha was achieved by adjusting the relative angle between the device and Arcan fixture, and the establishment of beta was achieved by adding thin copper pieces under one of the fixtures. The experimental tests indicated that when adopting the deflection curve deformation correction method, the obtained corrected mechanical parameters were similar to the results obtained from the uniaxial tensile test. The correction methods could be appropriate for the calculation of the true stress-strain curve on the condition of 2D misalignment, particularly for the correction of testing results obtained by in situ tensile devices with compact structure and miniature size.