Improved Detection of Localized Damage in Pipe-Like Structures Using Gradient-Index Phononic Crystal Lens

Abstract

AbstractIn this study, the fundamental torsional wave mode T(0, 1), generated by d35 piezoelectric transducers, is utilized in the detection of localized defects such as pitting corrosion. Numerical models based on the finite element method are built to simulate wave propagation and collect data in the time domain. A curved gradient-index phononic crystal (GRIN-PC) lens is implemented to redirect the plane wave to a single point where a single sensor is sufficient to record the interaction of plane wave with the pipe geometry. Parametric studies are carried out and generalized to determine the trends for different defect size, orientation, and axial positions. Signal difference coefficient (SDC) is selected as a damage index based on the modified dispersion properties and the results of principal components analysis. Since the damage information is focused at a single location, the need for using an array of transducers for sensing is eliminated. With the changes in the dispersion of T(0, 1) caused by the GRIN-PC lens, localized defects can be detected earlier than in a plain pipe, before they reach a significant thickness of the pipe wall.KeywordsPhononic crystalsGRIN-PC lensPipesDamage detection