Magnetostrictive Composite Sensors for Stress Sensing Applications Edward Lynch Ashraf Al-Hajjeh Department of Electrical Engineering University of Wisconsin -Milwaukee

Background Sensors were molded onto aluminum substrates in the form as rectangular prisms at angles of 0°, 30°, 45°, 60°, and 90°. The magnetostrictive composite stress sensors work on the principle of the Villari effect, also know as inverse magnetostriction. Inverse magnetostriction is a change in magnetic susceptibility when a mechanical stress is applied to a material. A magnetic circuit consisting of a toroidal sensing coil with an air gap core and sensor was formed. Inductance measurements were taken at the terminals of the coil. These measurements were then used to determine the relative change in susceptibility.

Relative change in magnetic susceptibility was determined from inductance measurements using the following relationship: Change in Magnetic Susceptibility Where L is the inductance for a given stress. L 0 is the inductance for zero stress, and L a is the inductance of the coil measured in air. This was determined through magnetic circuit analysis. A fit function was developed based on the experimental results: where χ is susceptibility at a given stress, χ 0 is the susceptibility at zero stress, C 1 and C 2 are fit parameters, σ is stress in the aluminum, and ϕ σ is the sensor rotation angle.

Results Percent change in magnetic susceptibility as a function of stress in the aluminum substrate. Fit function plots for each angle of sensor rotation.

Acknowledgements Faculty Advisors Chiu Tai Law, PhD Rani El-Hajjar, PhD Financial Support Research Growth Initiative (RGI) Thank You!