A piezoelectric guided wave sensor design method for crack monitoring of I-beam flanges

Abstract I-beams are widely used in industrial structural engineering, but their flanges are prone to localized damage during service. Ultrasonic guided waves have long-distance propagation capabilities in cross-section steel structures, making them suitable for damage monitoring of I-beams. However, existing test approaches rely on multiple piezoelectric sensors arranged into arrays, which may exhibit inconsistencies due to factors such as contact errors, measurement point locations, and connecting wires. To address this challenge, this paper develops an ad-hoc piezoelectric guided wave sensor for flange damage monitoring and assessment of hot rolled I-beams. The design process involves the analysis of dispersion characteristics, modal shapes, and energy distribution, the selection of a guided wave frequency suitable for flange monitoring of I-beams, and the regulation of the sensor’s resonant frequency. The results show that the designed sensor is capable of excitation and reception of ultrasonic guided waves in the flange with modal shapes dominated by the first-order mode. This method exhibits good sensitivity to flange cracks in I-beams with a damage rate ρ > 1.5%, providing a feasible solution for localized damage monitoring in cross-section steel structures.