Shock testing accelerometers with a Hopkinson pressure bar

Abstract

The electronic industry continues to dramatically reduce the size of electrical components. Many of these components are now small enough to allow shock testing with Hopkinson pressure bar techniques. However, conventional Hopkinson bar techniques must be modified to provide a broad array of shock pulse amplitudes and durations. For this study, we evaluate the shock response of accelerometers that measure large amplitude pulses, such as those experienced in projectile perforation and penetration tests. In particular, we modified the conventional Hopkinson bar apparatus to produce relatively long duration pulses. The modified apparatus consists of a steel striker bar, annealed copper pulse shapers, an aluminum incident bar, and a tungsten disk with mounted accelerometers. With these modifications, we obtained accelerations pulses that reached amplitudes of 10 kG and durations of 0.5ms. To evaluate the performance of the accelerometers, acceleration-time responses are compared with models that use independent stress and strain measurements. Comparisons of data from all three measurements are in good agreement.