A time delay-weighted total focusing method for lamb wave-based damage imaging in three-element dense arrays

This paper presents a three-element dense array weighted TFM Lamb wave-based damage detection method, aimed at reducing detection system costs while maintaining high damage detection accuracy in dense arrays. Initially, a three-element dense array configured in an equilateral triangular layout is utilized. The relationship between the time delay characteristics of the damage-scattered signals and the transducer arrangement is analyzed to perform region division, enabling preliminary localization of the damage area. Following this, a weighted coefficient is established by integrating the time delay and the detection position, enhancing the conventional TFM damage imaging index. Ultimately, the imaging results are obtained by performing additive fusion of all collected damage scattered information. The proposed method is validated using experiments conducted on a T300/3231 CFRP laminate with simulated damages. Compared to conventional TFM, results show that the proposed method demonstrates superior imaging performance, reducing the damage spot size, facilitating easier identification of the damage location and improving localization accuracy under the same conditions, while maintaining consistent detection accuracy at extended distances.