Assessment of early-stage damage in pipes using ZGV guided wave modes with PVDF comb transducers

Detecting early-stage damage in metal pipes poses significant challenges for existing structural health monitoring (SHM) techniques. This research presents an innovative approach for the damage assessment of early-stage in pipes using zero group velocity (ZGV) guided wave modes, generated and responded by polyvinylidene fluoride (PVDF) comb transducers. The fundamental properties of the comb transducers were initially analyzed. Subsequently, the performance of the PVDF comb transducer, designed for the ZGV mode, was evaluated through finite element simulations and experimental assessments. The results suggest that the PVDF comb transducers possess the ability to effectively generating and responding ZGV modes in pipes and are proficient in assessing early-stage damage in aluminum pipes. Furthermore, comparative analysis with the L(0,2) mode has shown that the spectral amplitude at the initial ZGV frequency serves as a more reliable indicator of early-stage corrosion damage on the inner wall, exhibiting a significant and monotonic decrease as corrosion progresses.