A FEM-Based Optimization Method for Driving Frequency of Contactless Magnetoelastic Torque Sensors in Steel Shafts

Abstract

This paper presents a novel finite element method (FEM) of optimization for driving frequency in magneto-mechanical systems using contactless magnetoelastic torque sensors. The optimization technique is based on the generalization of the axial and shear stress dependence of the magnetic permeability tensor. This generalization creates a new possibility for the determination of the torque dependence of a permeability tensor based on measurements of the axial stress on the magnetization curve. Such a possibility of quantitative description of torque dependence of a magnetic permeability tensor has never before been presented. Results from the FEM-based modeling method were validated against a real magnetoelastic torque sensor. The sensitivity characteristics of the model and the real sensor show a maximum using a driving current of similar frequency. Consequently, the proposed method demonstrates the novel possibility of optimizing magnetoelastic sensors for automotive and industrial applications.

Driving Signal and Geometry Analysis of a Magnetoelastic Bending Mode Pressductor Type Sensor

“…For now, with the hardware options that we have currently available, manufacturing the sensors from sheets, measuring their responses at various magnetizing current parameters, and analyzing the data are less time-consuming than simulating the sensors virtually when it comes to considerable bending of thin sheets. FEM simulations conducted by other researchers when considering problems similar in nature (magnetoelastic torque sensors, rather than magnetoelastic bending mode force sensors) were conducted, and outputs were defined by a sensitivity chart that showed local maxima of sensitivity in a given range of torque moments but not the actual waveforms [33], which are characteristics that are probably obtainable even from linearized simulation models that do not need to incorporate the truly nonlinear behavior of the material.…”

“…Further optimization of magnetoelastic sensors could make the differences between magnetoelastic and resistive load cells smaller; therefore, they could operate interchangeably in everyday life. Usually, FEM simulations are used for optimization, which tests the effect of various changes to the geometry and driving parameters from the perspective of linearity and other parameters [33]. Analytical expressions for the sensor's output voltage are available; however, only for basic shapes such as cylindrical rods, because of the mathematical complexity of the problem [34].…”