Abstract:

：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.

Key words: ambient temperature, applied loads, structural health monitoring, temperature compensation, ultrasonic guided waves