Guided wave-based bend detection in pipes using in-plane shear piezoelectric wafers

Abstract

Pipelines can exhibit various types of damage and aging defects during their long operating life. Some of the most typical causes of failure in pipelines are corrosion, stress rupture, seam weld cracks, material flaws, and externally induced damage by excavation equipment. Stress rupture due to large deformations, such as bending under an external loading, is an example of pipe damage. Compared with corrosion in pipes, the topic of bending deformation detection has been investigated less. In this study, the guided wave is employed to identify both the presence of a bend in a pipe and the bending direction with help of in-plane shear piezoelectric wafers. This type of piezoelectric wafer can sense the shear deformation, which occurs in the flexural mode guided wave owing to the bend. First, this paper reviews and analyzes the basic propagation characteristics of guided waves and the newly generated modes affected by the bend. Subsequently, numerical studies are performed to investigate the corresponding displacement components in presence of bend, and the voltage responses of the in-plane shear piezoelectric wafers. Accordingly, the layout of in-plane shear piezoelectric wafers can be determined to capture the newly generated modes owing to the bend. Finally, the proposed approach is validated experimentally in two steel pipes utilizing the mode conversion and in-plane shear piezoelectric wafers.