Transducer array optimisation for guided wave testing of pipes using finite element numerical simulations and experimental studies

Oil and gas pipelines are one of the major applications where the structural health monitoring (SHM) technology is particularly attractive.Ultrasonic guided wave (UGW) testing as an advanced non-destructive testing (NDT) technique enables the identification of defects and its location on the pipe circumference in use. In general, a circumferential array of piezoelectric transducers clamped around the surface of the pipe is employed. The sensitivity of the NDT operation is 3 - 9 %of cross-sectional area reduction, depending on the signal-to-noise ratio. The operation frequency range is typically from 20 kHz to 100 kHz. Optimisation of the transducer array design increases performance in pipe inspection without significant increase in manufacturing and testing costs, which is an area of interest for the industry. This paper presents research on the characterisation of circumferential array design using finite element analysis (FEA) models.The excitation of the fundamental torsional wave mode T(0,1) with flexural wave modes F(n,2) familyis used for pipe inspections. The related experimental testinghas been undertaken to verifythe FEA models. A range of notch dimensions have been introduced to the pipe model, and the T(0,1) with F(n,2) family interaction with these simulated defects is analysed. A series of parameters will be evaluated including transducer excitation variability, number of transducers per array and a gap between the start and end transducers of the array in a practical tool for pipe inspections. The characterisation of multiple transducer array design parameters and its performance could be obtained from the research results.