Non-contact torque sensor based on magnetostrictive Fe30Co70 alloy

A non-contact torque sensor based on a magnetostrictive Fe30Co70 rod wound with an excitation coil and a pickup coil is proposed in this paper. In the magnetic field range 0–30 kA/m, the changing rate and linearity of magnetostriction with a loading magnetic field of Fe30Co70 samples are significantly improved after heat treatment. Maximum magnetostriction is 103 ppm in the annealed sample in the parallel direction, while its tensile strength and allowable shear stress are 608 and 194.56 MPa, respectively. According to the mathematical model presented in this work, there is a linear relationship between the output voltage and torque. An apparent increase in the induced voltage signal (peak voltage) of 48.23 mV is observed as the torque increases to 20 Nm in the case of applying sinusoidal excitation signals. In addition, the experimental results are consistent with the calculated values within the torque range 0–16 Nm, and a good sensitivity of 2.87 mV/Nm is obtained. This work shows the prospect of Fe30Co70 alloy for non-contact torque sensing for the appropriate magnetostrictive property with no orientation requirement.