Graduate students

Graduate students

Claudio Acuña Pavese, 2022, “Thickness gauge using the eddy current method”.

Technical summary

Non-destructive testing (NDT) by eddy currents (EC) is a reliable evaluation method that is applied in different areas such as nuclear, the petrochemical industry, air and rail transport, among others. The wide use of coating meters is known, both in different industries and in research and development laboratories. Generally, these devices are manufactured to perform measurements on a limited number of substrates, reducing the range of applications. In this context, the project aims to develop and implement artificial neural network (ANN) algorithms and build a functional prototype for field application in an embedded system. The sensor is composed of a Colpitts oscillator. The impedance of the resonator tank is modified according to the lift-off (in EC lift-off is called the separation between the probe and the component to be inspected), and this generates changes in the resonance frequency. The system calibration curve is determined through the variation of the resonance frequency as a function of the lift-off. Eddy currents method, like all NDT methods, is a comparative method that needs a calibration curve in order to be implemented. The sinusoidal signal coming from the probe enters the embedded system that will be in charge of conditioning it. In the next stage of the device, a calibration must be performed depending on the substrate being used. Calibration is performed by training an ANN, which will have the output frequency of the oscillator as data set according to the thickness of standard gauges. In the last stage, the trained ANN will return the value of the coating thickness and this parameter will be displayed on an HMI interface or screen. The system will be powered by a rechargeable battery and recharging will be through an external power supply. The portable device must work with thicknesses between 25 and 905 microns on 6061 aluminum and Zry-4. Consequently, this project will contribute to the research and development group "Non-destructive testing applied to the railway industry" of the Haedo Regional Faculty and to the industry that uses this measurement technique.

Graphical abstract