Influences of magnetic circuit structure of magnetostrictive guided wave transducer on the homogeneity of bias magnetic field

摘要

The uniform and steady bias magnetic field is the key to improvement of the transduction efficiency for the magnetostrictive guided-wave transducer. To optimize the magnetic circuit of the magnetostrictive transducer and obtain the best detection effects, the method to measure the homogeneity of magnetic flux density by sample standard deviation was studied. And the effects of such parameters as the thickness of the left and right enclosed magnetic conductor shell, the thickness of the outside round shell of magnetic conductor, the distance between the bias magnetic exciting coil and the pipe's outer wall on the homogeneity of the excited bias magnetic field were analyzed quantitatively, both finite element simulation and experimental analysis were conducted to study the effects of different magnetic circuit design schemes on the excited bias magnetic field's homogeneity. The simulation results indicate that the homogeneity of the magnetic field is obviously improved with the above three parameters increasing, and the relatively uniform magnetic field can be obtained when the above parameters are all taken the maximum value of 20 mm.