摘要

The authors have proposed a fast electromagnetic acoustic transducer (EMAT) for the online measurement of the wall thickness of steel pipes. Rather than testing in a relative helical scanning configuration, the proposed EMAT configuration is suitable for full coverage linear scanning, as it provides multipoint local magnetic fields, all of which pass vertically through the coils surrounding the pipe. A comparison of 3D numerical models developed for both EMAT configurations show that the proposed EMAT configuration provides a stronger flux density with nearly no net magnetostatic force on the pipe. Magnetic field distributions are presented, and experimental results validate the simulated predictions. A preliminary thickness measurement system demonstrates the effectiveness of the proposed design.