Reconfigurable Time-Reversing Transducer for Guided Wave Inspection of Pipes

Pipelines are critical for fluid transport but prone to corrosion in hard-to-access or insulated regions such as under pipe supports (CUPS). Ultrasonic guided waves (GWs) are widely used to inspect pipes since they can provide tens of meters of coverage from a single sensor location. However, conventional GW inspection systems often lack the sensitivity and resolution needed to detect subtle flaws or to inspect geometrically complex regions. Wave energy focusing has shown promise in enhancing sensitivity and signal-to-noise ratio (SNR), but traditional phased array systems require numerous individually controlled transducers and complex hardware. This study introduces a reconfigurable time-reversing transducer (TRT) that achieves wave focusing through a novel programmable and low-complexity design. The proposed TRT employs a discrete grid of 128 miniature piezoelectric elements that can approximate a time-reversed wavefield and re-emit it to achieve spatial focusing. The elements are controlled with only four actuation channels by dynamically clustering them, greatly reducing hardware complexity. Finite element simulations on a steel pipe demonstrate that the TRT can concentrate ultrasonic energy at target locations, yielding a highly directional beam and significantly increased signal amplitude at the focus compared to unfocused excitation.