An Improved Adjacent Wave Subtraction Method for Damage Detection in Stiffened Composite Panels

The stiffened composite panels are widely used in various engineering structures, but their nondestructive testing methods face certain limitations. The traditional wave field imaging method faces difficulties when applied for damage detection in complex composite structures. An improved adjacent wave subtraction (AWS) method is proposed in this research to visualize the multiple damage in stiffened composite panels. The method is based on the concept that the Lamb wave signals from two adjacent scanning points at healthy area are very similar and the anomalous wave, caused by the structural discontinuities including the damage, has different signal packets at any two adjacent scanning points. The mode Lamb wave signals are used in the proposed AWS method due to their faster speed in low-frequency domains. A damage index is proposed to show the signal difference of any two adjacent points, which can indicate the damage locations. A robust time window is used to enhance the anomalous wave signals and improve the damage imaging results. The prosed method is proven to be effective for damage detection in stiffened composite panels with numerical simulations and experiments.