Sensor optimisation and the design of a scanning platform for electromagnetic imaging of defects over large plates

Abstract

<b><sc>Abstract.</sc></b> <b>Eddy current sensors with improved sensitivity and spatial resolution contribute to acquiring an accurate scanning imaging of a defect in a plate work piece. This thesis focuses on the optimization of the angle between the transmitter and receiver coils. It is found that the angle affects the sensitivity and spatial resolution and at a particular angle, these indexes approach the best performance. Besides, the design of a scanner which can cover a large scanning area and was carried out. This expands the current capability of the research group and provides a platform to clamp the sensor and adjust its height for future experiments. Under this circumstance, the experiments in this project are to test mutual inductances of two coils with varying configurations utilizing an impedance analyzer and the sensitivities and measure the spatial resolutions with an X-Y scanner in small size separately. After testing these indexes under different arrangements, a conclusion could be drawn that when the angle between the transmitting and receiving coils grows, the mutual inductance between two coils decreases while the spatial resolution increasing. As a result, the performance with the degree being set to be 75° is better after balancing these two indexes. Finally, a large steel plate with defects has been scanned by this T-R sensor and the cracks can be detected in the images drawn by MATLAB.</b>