霍普金森压杆过载实验弥散分析

Dispersion analysis in Hopkinson pressure bar high-g loading experiment

为准确获取霍普金森压杆高过载实验中试件加速度,用快速傅里叶弥散分析方法对入射波传播过程进行弥散修正,比较沿压杆轴向不同位置处加速度状态,分析弥散修正前后不同脉冲加载时试件加速度峰值及脉冲偏差。结果表明,弥散效应可导致压杆不同位置处加速度状态存在差异,火工品试件所受过载加速度峰值偏差在10%以上;脉冲宽度偏差因波形而异,绝对偏差均小于6μs;对含高频成分的弥散波,欲精确获得试件过载加速度需进行弥散修正。

The dispersion effect in the Hopkinson pressure bar high-g loading technique is caused by the lateral inertia motion of particle,leading to an inaccurate acceleration in peak and duration.Based on the Fast Fourier Transform （FFT）approach,the dispersion effect was corrected.Then,acceleration pulses at different locations along the pressure bar were compared to check the dispersion effect.In addition,before and after dispersion correction,the acceleration pulses on the specimen were investigated under different pulse loadings,and the errors of the peak and duration were analyzed.The results show that the acceleration pulses at different locations of the bar are different in peak and duration due to the dispersion effect,and the error of the peak acceleration on the initiator is more than 10%.The error of the acceleration duration depends on the pulse shape,but the absolute error is less than 6μs.As for the dispersive pulse, dispersion correction is a necessary procedure to obtain a more accurate acceleration pulse.