识别疲劳裂纹损伤的瞬时基准方法研究
Study on Fatigue Crack Damage Detection with an Instantaneous Baseline Method

传统的基于超声导波的结构健康监测及损伤识别方法是通过对比当前测量信号与结构完好时的基准信号进行损伤识别，但这类基准信号对工况及环境变化十分敏感。为降低对这类基准信号的依赖，提出了一种基于瞬时基准的疲劳裂纹损伤识别方法。利用疲劳裂纹在不同幅值激励下不同的超声非线性特性，以小幅值激励下结构响应为瞬时基准信号，以大幅值激励下结构响应为当前信号，使用比例相减法提取当前信号与瞬时基准信号间的差信号，对疲劳裂纹损伤进行识别。分别以完整铝梁及疲劳裂纹铝梁为实验对象，使用压电片激励和接收应力波信号。实验结果表明，该瞬时基准方法可有效识别疲劳裂纹损伤，而无需结构完好时的基准信号。
Conventional guided wave based damage detection often compares newly collected response to a prerecorded baseline directly, but these baseline signals are very sensitive to varying environmental and operational conditions. To overcome those deficiency, an instantaneous baseline method is proposed. Based on the nonlinear properties of fatigue damage varies with the amplitude of excitations, the instantaneous baseline is collected when a small amplitude excitation is applied and the current signal is collected when a large amplitude excitation is applied. A scaling subtraction method is adopted to get the difference between the current signal and the instantaneous baseline. Experimental tests are performed on an intact aluminum beam and a cracked beam, two PZT transducers which used to excite and sense the wave signals are bounded on two sides of each beam. Experimental results demonstrate the applicability and effectiveness of the instantaneous baseline method