Non-Contact Thickness Measurement System Using a Smart Cantilever Beam

Abstract

The paper presents the design, fabrication, and experimental validation of a new non-contact resonance-based measurement system to measure the thickness of ferromagnetic sheets and their alloys. The measurement system consists of a cantilever beam as a resonating structure with electromagnetic excitation and piezoelectric detection. The system measures the unknown thickness of a ferromagnetic sheet by measuring the resonance frequency of the cantilever beam resonator. The resonator vibrates at different resonance frequencies depending on the thickness of the ferromagnetic sheet. The electromagnet and the piezoelectric patch are connected with appropriate electronic circuitry for resonance excitation and detection of the resonator. The electronic circuitry will automatically track the resonance frequency of the measurement system for a variation in the ferromagnetic sheet thickness. A complete analytical model of the measurement system was developed and evaluated through experimentation. The analytical and experimental results are found to be in good agreement. The proposed measurement system is simple in design, compact, low cost, and its frequency output decrease linearly with an increase in thickness of the ferromagnetic sheets.