Optimization of Magnetoelastic Torquemeter Designs

The performance of magnetoelastic torquemeters based on the changes in a measurable magnetic field is obtained with a simplified numerical model, assuming isotropic magnetoelastic properties throughout the ferromagnetic shaft and independent magnetic cells. The output gain of two torquemeter designs is obtained as a function of the distance of the magnetometers and width of the magnetic bands. Results show that a radial sensor configuration gives a gain 1.76 times larger in average than an axial sensor configuration. It is also shown that the radial configuration is more sensitive to magnetometer position errors and requires a tighter control over the device parameters to maintain a constant gain. Furthermore, computations reveal that fluctuations in the magnetization of the shaft decrease the gain and increase the signal offset and that the shaft radius can alter this dependence due to an enhanced magnetoelastic response.