Intelligent search imaging method based on amplitude fusion for damage detection of multilayer thin-walled plates using ultrasonic guided waves

Abstract

Due to material lamination and interface coupling in multilayer structures, ultrasonic guided waves exhibit increased dispersion and intensified mode conversion. These phenomena cause problems such as localization deviation, imaging artifacts and degraded detection accuracy for bottom-layer damage. Therefore, for the damage detection at the bottom layer of multilayer thin-walled plate structures, this paper proposed an intelligent search (IS) imaging method based on amplitude fusion. First, each individual in the population is assigned an amplitude according to the propagation time mapped to the scattered signal time series. Subsequently, the amplitude responses from every sensing path are combined to yield a total amplitude, which serves as the fitness function. The fitness function evaluates the quality of the population, and an IS mechanism is employed to perform iterative optimization, allowing the population to gradually converge toward the damage area. Furthermore, a two-dimensional histogram is constructed to facilitate visual imaging of the damage. Experimental results indicate that, compared to the reconstruction algorithm for probabilistic inspection of damage method and the delay-and-sum method, the proposed method exhibits superior localization accuracy (improved by more than 70%) and imaging focusing performance in damage imaging of the multilayer structures.