Ultrasonic evaluation of early damage of a coating by using second-harmonic generation technique

作者：Shui Guoshuang^*; Wang Yue Sheng

来源：Journal of Applied Physics, 2012, 111(12): 124902.

DOI：10.1063/1.4729300

For an in-service structure with a coating, damage accumulation may develop gradually within the coating or at the interface between the substrate and coating under external loads. By considering the fact that different levels of external load are closely related to the degrees of accumulated early damage which is very difficult to be measured directly, and that the early damage may cause the nonlinearity of Rayleigh surface waves, the acoustic nonlinearity parameter (ANP) is employed as an indicator of early damage of a coating. This research reports on the experimental observation of the monotonic correlation between the ANP measured with nonlinear Rayleigh waves and the applied stress on an AZ31 magnesium alloy plate specimen using ultrasonic second-harmonic generation technique. Rayleigh waves are generated and detected with wedge transducers, and the nonlinearity parameters are measured at different stress levels for the specimens with coatings. The result shows that there is a significant increase in the nonlinearity parameters with the increasing tensile stress although there is no obvious change for the coating when the tensile stress is less than a certain level. The research suggests an effective nondestructive evaluation method to track the coating damage using the higher order harmonic generation technique.

• 出版日期2012-6-15
• 单位北京交通大学