Microcracks Detection Based on Shuttle-Shaped Electromagnetic Thermography

Abstract

Nondestructive testing for natural microcracks is a critical challenge in assessing the surface and subsurface integrity of material. This paper proposes a shuttle-shaped sensing model with wide open inspection based on eddy current pulsed thermography (ECPT) system for natural microcrack detection on the specimens with complex geometry. To decrease the noise interference caused by uneven heating, the proposed model induces a unidirectional and uniform electromagnetic field in the region of interest. It significantly enhances thermal contrast and signal-to-noise ratio between non-defective and defective areas as well as improving the detectability and adaptability to different subjects. Besides, the direction of the infrared camera with respect to the specimen is set parallel to the specimen, which benefits the collection of the thermal signal. Experiments for several conductive cracks are implemented to verify the detectability of the proposed model.