Curved surface bandgap metamaterial-based ultrasonic guided wave spatial decoupling for zoned detection of double layer pipe

Abstract

The damage detection of double layer pipe using ultrasonic guided wave is hindered by the signal aliasing between the outer pipe and inner pipe, making it difficult to extract effective signal for damage localization and thus complicating damage assessment. To address this challenge, this study proposes a curved surface bandgap metamaterial to spatially decouple the ultrasonic guided wave of the outer and inner pipe in double layer pipe, thereby achieving precise spatial partitioning of guided wave. The metamaterials are strategically deployed on the outer pipe surface, utilizing their bandgap functionality to obstruct guided waves at 100 kHz, effectively confining the ultrasonic guided wave to two independent propagation domains: the “outer pipe region” and the “inner pipe region.” Owing to the structural universality of the curved surface bandgap metamaterial, a genetic algorithm is employed to perform a global optimization of its structural parameters, resulting in an optimal configuration that achieves both a wide and appropriate bandgap. Numerical simulations and experimental validations have confirmed that the proposed metamaterial partitions ultrasonic guided wave into spatially distinct domains. Furthermore, precise positioning of inner pipe damage and outer pipe damage in the double layer pipe has been achieved using the decoupled guided wave signals for detection. This study demonstrates the application of metamaterials in nondestructive testing of complex pipelines, highlighting their significant potential in this field.