Non-destructive testing and evaluation of elastic modulus of pipeline based on flexible EMAT

Transportation pipelines operating under long-term harsh environmental conditions are susceptible to safety hazards such as cracks and corrosion, primarily due to the degradation of material properties. Among these properties, the elastic modulus serves as a critical indicator of the mechanical performance of a material. This study proposes a novel non-destructive evaluation (NDE) method for estimating the elastic modulus of pipelines using electromagnetically induced ultrasonic guided waves. A specially designed non-contact flexible electromagnetic acoustic transducer (EMAT), capable of conforming to curved pipeline surfaces, is developed to enable accurate modulus assessment prior to crack formation. The propagation behaviour of guided waves in pipelines and the operating principles of the flexible EMAT are first examined. To overcome the challenge of low energy transfer efficiency inherent to flexible EMATs, the study systematically identifies key influencing factors and optimises the design parameters through a combination of finite element simulations and experimental validations. Leveraging the optimised EMAT and a calibrated relationship between elastic modulus and guided wave dispersion curves, the proposed method is validated via both numerical and experimental approaches. Simulation results for six Q235 pipeline samples with moduli ranging from 208 GPa to 213 GPa demonstrate a relative error within 1.2%, while experimental tests on Q235, 304 stainless steel and Al6061 yield errors below 1.3%. The proposed technique offers a reliable and effective approach for pipeline health monitoring and remaining life evaluation, contributing significantly to the prevention of failure incidents in critical infrastructure systems.