Aiming at the problem of difficulty of force decoupling and inconformity between test stress state and calibration when piezoelectric dynamometer with four point layout is used

a simultaneous calibration is put forward. Based on the test model of dynamometer

a force-electricity equation is set up

the model for forceelectricity conversion coefficient is derived

and the disturbance analysis and error transfer analysis are carried out.21 characteristic points are selected on the surface of the dynamometer

the loading experiment is carried out

the test force value is calculated and the distribution of the test error on the upper surface is analyzed. Experimental results show that the maximum test error of the simultaneous calibration method is only 0. 376 %

the linearity is less than 0. 33 %

and the repeatability is less than 0. 26 %. It proves that the simultaneous calibration has high precision and the calibration method is effective on the upper surface of dynamometer.