Implementation of primary low-g shock standard for laser interferometry

Abstract

This paper presents the novel implementation of a primary standard for low-g shock acceleration calibration based on rigid body collision using laser interferometry at National Institute of Metrology (NIM), China. The combination of an electromagnetic exciter and a pneumatic exciter as mechanical power supply of the shock excitation system are built up to achieve a wider acceleration range. Three types of material for shock pulse generators between airborne anvil and hammer are investigated and compared in the aspects of pulse shapes and acceleration levels. A heterodyne He-Ne laser interferometer is employed for precise measurement of shock acceleration with less electronic and mechanical influences from both the standard device itself and its surroundings. For signal acquisition and processing, virtual instrument technology is used to build up data acquisition PXI hardware from National Instrument and calibration software developed by LabVIEW. Some calibration results of a standard accelerometer measuring chain are shown accompany with the uncertainty evaluation budget. The expanded calibration uncertainty of shock sensitivity of the accelerometer measuring chain is 0.8%, <i>k</i>=2, with the peak range of half-sine squared acceleration shape from 20m/s2 to 10000 m/s2 and pulse duration from 0.5 ms to 10 ms. This primary shock standard can meet the traceability requirements of shock acceleration from various applications of industries from automobile to civil engineering and is used for piloting ongoing international shock comparison APMP.AUV.V-P1.