A New Resonance-Based Method for the Measurement of Nonmagnetic-Conducting-Sheet Thickness

A measurement system to measure the thickness of a nonmagnetic conducting sheet is designed, simulated, developed, and tested. The measurement system is designed as a resonant system with a cantilever being a resonating structure with piezoelectric excitation and detection. The permanent magnets at the tip of the cantilever beams produces an oscillating magnetic field, and the insertion of the conducting sheet in the magnetic field produces eddy current on it. The magnetic field produced due to eddy current alters the magnetic field produced by the permanent magnet. This alters the natural frequency of the measurement system as the stiffness due to the magnetic force varies with thickness. The simulation and experimental results show that the resonant frequency of the measurement system varies linearly with thickness and sensitivity is found to be higher for the material having higher conductivity.