The effect of rotation and force misalignment of standard load cell on tension/compression testing machine calibration

Abstract

The purpose of this research is to present the effects of load cell rotation and force misalignment during the calibration of a tension/compression testing machine according to ISO 7500-1:2018 (E). A 1000 kN testing machine, resolution 0.5 kN, class 0.5, was calibrated under 3 different conditions: case A, standard load cell was not rotated and force misalignment, case B, standard load cell was rotated to 0 degrees, 120 degrees, and 240 degrees, and case C, standard load cell was not rotated but force misalignment from the force center by 10 mm. When verification of results obtained from three cases was conducted the class of machine range to 0.5 class. The parameters of the test results of case A and B were not different. However, in cases A and C, the relative errors of reversibility were found to be up to -0.45%, and the uncertainty of the calibration at the 95% confidence level were different and increased up to ±0.53%, with respect to the increasing magnitude of the applied force. When comparing the results using E_n number method, the values were found between 0.05 -0.89, and the difference was not significant. When more force was applied, the E_n number increased slightly. This can be concluded that for tension/compression testing machine and standard load cell of a good class, the standard load cell rotation does not affect the calibration, but the force misalignment does.