A Method for Synchronous Shock Calibration of Triaxial High-g Accelerometers Based on Modified Hopkinson Bar Technique

Abstract

Since the width of the excitation pulse is generally in the order of microseconds to milliseconds, the key technique in the shock calibration of triaxial high-g accelerometer is how to achieve the synchronous loadings with high-g amplitude along the three orthogonal axes. Given this background, this paper developed a synchronous calibration method for the triaxial high-g accelerometers by modifying the conventional Hopkinson bar method. Using this newly developed method, three-dimensional reference acceleration pulses with amplitude range of 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sup> g-10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sup> g and width range of 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sup> μs-10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> μs can be generated and imposed on the triaxial high-g accelerometers synchronously. Then, calibration experiments on a typical triaxial high-g accelerometer were carried out by using both the synchronous calibration method and the conventional Hopkinson bar method, respectively. The sensitivity of the triaxial accelerometer was characterized by a matrix, the so-called sensitivity matrix, containing 3 main sensitivity coefficients and 6 transverse sensitivity coefficients. Least squares method (LSM) was used to calculate the sensitivity matrix. Generalization error was employed to evaluate the measurement accuracy of the accelerometer. The results show that the measurement accuracy of the triaxial high-g accelerometer calibrated by the synchronous method is higher than that calibrated by the conventional asynchronous method. Therefore, the developed synchronous method is recommended to ensure and improve the measurement accuracy of the triaxial high-g accelerometers. Finally, the validity and the calibration ability of the newly developed method were numerically investigated and discussed in detail.