A novel load ratio calculation method for calibrating force

ABSTRACTWelding force is a core parameter of Friction Stir Welding, whose accurate measurement and characterisation is an important guarantee for the welding quality of Friction Stir Welding. In this paper, the load ratio calculation method for calibrating force is proposed based on piezoelectric measurement system. The mathematical model and test model of piezoelectric dynamometer with parallel layout, both share-loading pillars and piezoelectric sensors, are designed based on piezoelectric sensors’ structure of four-point square layout, calibration tests for piezoelectric dynamometer are accomplished, and the calibration curves between different loading positions and output voltage of sensors with different standard forces based on Lagrange polynomial interpolation method are obtained. A novel load ratio calculation method is proposed, which solves the problem that there is larger deviation for axial output of piezoelectric sensor when force loads on different loading positions and achieves accurate mea...