Finite difference time domain simulation of ultrasonic phased array sector scan for imaging cracks in large pipes, elbows, and tee sections

This article reports simulation studies of ultrasonic wave generation and reception using the sector scan feature of a phased array transducer to image and size crack-like defects in large pipes, elbows, and tee sections. The simulations were based on a two-dimensional implementation of the Finite Difference Time Domain (FDTD) method. Experiments were conducted to validate modeling results for pulse-echo simulations of the phased array transducer on pipe samples with notches of three different sizes. The defects were imaged using the sector scan mode of the phased array and sized using the Absolute Arrival Time Technique (AATT). A 64 element, 5 MHz linear phased array transducer with the ultrasonic beam swept over an angular range of 10°-75° (refracted angles), directly in contact with the specimen, was used. Simulation and experimental studies were also conducted to image and size cracks in elbow and tee section pipes.