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提出了一种利用光纤布拉格光栅实现对分离式霍普金森压杆产生的应力波的检测方法,简述了其工作原理,并且探讨了杆中产生的应变与光纤光栅中心波长漂移量间的关系。将光纤光栅及应变片均沿轴向对称粘贴于被测圆柱杆同一截面的外侧,对两杆直接撞击及通过波形整形器撞击后杆中产生的应变脉冲进行了检测。在上述两种情况下,将光纤光栅及应变片的检测结果分别进行对比分析,发现两者时域波形吻合;对其进行频谱分析,两者频域成分一致。当撞击速度为11.33m/s时,光纤光栅测得的最大应变为-1087.04με,其相对误差为2.26%;粘贴波形整形器后,撞击速度为9.8m/s,光纤光栅测得的波速为5236.4m/s,其相对误差为2.84%,误差范围基本能满足工程测试的要求。
A method of detecting stress wave generated by split Hopkinson pressure bar by using fiber Bragg grating is presented. Its working principle is briefly described. The relationship between the strain generated in the rod and the shift of the center wavelength of the fiber grating is also discussed . The fiber grating and strain gauge are axially symmetrically affixed to the outside of the same cross-section of the cylinder rod under test. The direct impact on the two rods and the strain pulse generated in the rod after impact by the waveform shaper are tested. In both cases, the results of fiber grating and strain gages were compared and analyzed respectively. The results show that the time-domain waveforms of the two are coincident with each other. When the impact velocity is 11.33m / s, the maximum strain measured by FBG is -1087.04με, the relative error is 2.26%. The impact velocity is 9.8m / s after affixing the waveform shaper. The wave velocity measured by the FBG is 5236.4m / s, the relative error is 2.84%, the error range can basically meet the requirements of engineering test.