Analysis of high acceleration shock pulses part II: Pulse shaper material

This is the second of two papers that deal with the investigation of a velocity amplification rig designed to create shock pulses capable of exciting micro-scale devices. A companion paper demonstrated the acceleration response spectrum induced on three ultimate masses of different geometries. It highlighted the accelerations achievable by means of velocity amplification and specifically analyses the pulse propagation through each mass. It also showed that the use of an isolated insert in the ultimate mass refined the shock pulse and improved the repeatability of the system. This paper looks at a discrete analysis of impact materials used to shape the duration and amplitude of the incident pulse. Hemispherical tipped impacters of steel, aluminium and nylon are used over a range of impact velocities to smooth the excitation pulses delivered by short duration high-g impacts on a steel rod. A comparative study of acceleration amplitudes and frequency distribution was carried out using signal analysis techniques. The experimental analysis yielded the acceleration ranges of the materials for a specific impact velocity. A 10,000g pulse was generated for each material for comparison of the time/frequency domains using wavelet analysis. This paper shows the feasibility of using different impact materials to obtain a specific shock duration for a set acceleration level.