Abstract: A novel integrated sensor structure is presented for detecting defect and measuring stress level of ferromagnetic material waveguides while it works as magnetostrictive sensor(MsS) and elastomagnetic sensor(EMS) alternatively. This dual-mode integrated sensor includes bias magnetic circuit and inner-, outer-sensing coil. According to the basic theory of magnetostrictive and elastomagnetic effect, the bias magnetic circuit is optimized using finite element method in which the energy conversion efficiency and stress measurement sensitivity are estimated as the criterion of sensor performance. When the integrated sensor works as MsS, the experimental results show that it can excite L(0,1) mode guided wave in a 6.3 mm diameter steel rod to detect a notch of 1 mm in both depth and width. The defect detection capability can be enhanced by increasing the current flowing through the outer sensing coil. When the integrated sensor works as EMS, its stress measurement sensitivity and the linearity of measured curves can be improved by increasing the excitation signal amplitude. The highest linear regression coefficient of measured curve reaches 0.992 4, so that the presented integrated sensor can be applied for highly precise stress measurement.

Key words: Defect detection, Elastomagnetic, Integrated sensor, Magnetostrictive, Stress measurement