Abstract：The video extensometer is used to measure the deformation of the material and needs online calibration and calibration. However, there is there is no guidance of corresponding standards and calibration specifications. An online calibration device of grating extensometer is designed, which is mainly composed of the controller, stepping motor, mechanical transmission mechanism, grating displacement sensor, a display and the composition of board, the calibration on board.The third-party calibration results show that the maximum relative error of the calibration distance is 0.07% (Urel=0.04%,k=2).Technical index of grating displacement: when less than or equal to 1/3mm, absolute error is less than 0.3μm (U=0.1μm, k=2); when greater than 1/3mm, relative error is less than 0.1% (Urel=0.04%, k=2), the technical index is obviously better than the requirements.The device is used to verify the repeatability and stability of the video extensometer, and the uncertainty of the calibration results is evaluated. The results show that the technical specifications of the device can fully meet the online calibration of the video extensometer.
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2022, Vol. 43 
