Piezoelectric transducer array optimization through simulation techniques for guided wave testing of cylindrical structures

Guided wave testing as an advanced non-destructive method is a fast-growing field in structural health monitoring of engineering structures. Oil and gas pipelines are one of the major applications where the technology is particularly attractive. This is mainly due to the ability of guided waves to propagate over long distances (up to tens of meters) with a high sensitivity to changes in the structure on the propagation path. Guided wave testing enables the identification of defects and its location on the pipe circumference. Commonly a circumferential array of piezoelectric transducers clamped around the surface of the pipe is used to transmit and receive guided waves. The sensitivity of the operation is of 3 - 9 % of cross-sectional area reduction, depending on the signal-to-noise ratio. Optimisation of the transducer array design to increase performance in pipe inspection without significant increase in manufacturing and testing costs, is an area of interest for the industry. In this paper is presented part of the on-going research been carried out focusing on ultrasonic guided wave inspection of steel pipe structures. Here is described the propagation characteristics of an individual transducer and the propagation and defect sensitivity of a circumferential array design using finite element analysis (FEA) models with excitation of the axisymmetric torsional wave mode T(0,1).