Study on several key problems in shock calibration of high-g accelerometers using Hopkinson bar

In this paper, we studied several key problems in the shock calibration of high-g accelerometers, in which the Hopkinson bar system was employed as the loading and testing device. Firstly, in order to generate a strain pulse (the excitation signal in shock calibration) with high amplitude and a wide frequency bandwidth, the pulse shaping techniques by adjusting the geometry of projectile were numerically investigated. It was found that a smaller degree of taper at the front end of the projectile causes lower amplitude and wider duration of the acceleration pulse. The findings in studying pulse shaping technique could guide the choice of the projectile's geometry in the dynamic linearity calibration of accelerometers. Second, a novel method of the dynamic linearity calibration for accelerometers was proposed and verified by experimental tests. In the calibration process, we employed a single-barrel gun instead of the double-barrel gun (proposed in earlier studies) to launch two coaxial cylindrical projectiles, such that the synchronous impact of the two projectiles can be easily achieved in practice. Lastly, the efficiency of this developed calibration method was discussed in details. The calibration system used in this study is able to achieve a testing range from thousands of g to nearly 300,000 g.