A Dual FBG Magnetic Field Sensor Based on Rod-Shaped Terfenol-D Material

Magnetic field measurement plays an important role in many fields such as navigation, aerospace, mineral exploration, and smart grid. To address the current issues of low sensitivity and susceptibility to temperature of fiber Bragg grating (FBG) magnetic field sensors, a dual-FBG magnetic field sensor based on giant magnetostrictive material (Terfenol-D) is proposed. First, the sensor model is established using SolidWorks and the strain transfer theory is analyzed. Second, prestress and bias magnetic field are applied to the Terfenol-D rod to optimize the performance of the sensor. At the same time, the method of reference fiber is adopted to compensate the temperature of the sensor. Finally, the physical sensor is developed and a magnetic field test system is built for performance testing. The experimental results show that when the prestress is 6 MPa, the sensor achieves the best performance, with a magnetic field sensitivity of 56.8 pm/mT and a magnetic field measurement accuracy of $35.2~\mu $ T, and the sensor’s directivity basically conforms to the cosine law. The research results are expected to be applied to magnetic field measurement in harsh environments such as high temperature and high pressure.