变化环境下的超声导波结构健康监测研究进展

Progress on the Research of Ultrasonic Guided Wave Structural Health Monitoring in the Changing Ambient

超声导波结构健康监测(Structural health monitoring,SHM)在大规模板和管结构的缺陷诊断中是一个极具吸引力的检测技术。不同研究者均证实环境和操作条件变化,特别是温度和外加载荷变化会掩盖由缺陷引起的信号变化从而限制SHM系统的性能。分别就环境变化中温度和外加载荷对SHM系统中超声导波传播机理的影响进行综述:环境温度的变化会引起样本热膨胀系数和弹性模量的改变,进而影响超声导波在结构中的传播,且相比于超声纵向导波,横波对温度的敏感度较低;外加载荷对导波传播的影响主要体现在时移、幅值及相位的变化上。针对温度变化对导波结构健康监测造成的影响,详细阐述温度补偿法的研究进展,为更好地辨识由缺陷引起的变化和由周围环境引起的良性变化奠定理论基础,为后续超声导波SHM的研究指明方向。

Ultrasonic guided wave structural health monitoring（SHM） is an attractive technique in the diagnosis of large scale structure, such as board and tube. It has been demonstrated by different authors that environmental and operating conditions, especially temperature and applied loads variations may cover up the signal changes caused by the defects, which consequently limit the performance of SHM system. The effect of environmental changes in temperature and load on ultrasonic guided wave propagation mechanism in SHM system are discussed：The variations of ambient temperature may evoke changes in sample thermal expansion coefficient and elastic modulus, thereby affecting the propagation of ultrasonic guided waves in the structure, in addition, compared to ultrasonic longitudinal guided waves, there exist a lower temperature sensitivity in shear; the effect of applied load on the guided wave propagation is mainly reflected in the change of time shift, amplitude and phase.In view of the influence about ambient temperature on guided wave structure health monitoring, the progress of temperature compensation strategies is also discussed in detail aiming to provide a theoretical foundation for better identifying variations caused by the defect and the benign changes due to the surrounding environment and indicate directions for subsequent ultrasonic guided wave SHM research.