A Cross-Scanning Crack Damage Quantitative Monitoring and Imaging Method

Quantitative crack monitoring and detection is one of the focuses of attention to structural health monitoring due to its concealment and harmfulness. However, in the existing guided wave- and PZT-sensor-array-based structural health-monitoring approaches, the crack orientation information is often ignored, which is a key issue in crack monitoring, making it hard to effectively evaluate the crack damage. In this study, the circular piezoelectric array and active Lamb wave RAPID imaging technology are introduced and improved to study the quantitative monitoring of crack damage. A cross-scanning method is proposed to determine the crack orientation based on response signal variations of different degrees on monitoring paths with different angles. Accordingly, the signal difference coefficient (SDC) value of the detected monitoring paths of parallel or approximately parallel crack damage is corrected to strengthen the reconstruction information of crack orientation. After that, image reconstruction and quantitative evaluation of crack damage can be realized based on the enhanced SDC information. Several experiments are carried out on the aluminum plate to validate the proposed method. The cracks at different positions and orientations are monitored and evaluated through the proposed method. The experimental results show that crack orientation can be well identified through the proposed cross–scanning crack monitoring and imaging method.