A Portable Hybrid Ultrasound-Eddy Current NDI System for Metal Matrix Composite Track Shoes

Track shoes made of Metal Matrix Composite (MMC) are light in weight, and can resist high temperature and wear. Defects such as disbond, cracks and porosity can be introduced during the manufacturing process and while in service. Presented in this paper is a portable nondestructive inspection (NDI) system to automatically inspect the tank track shoes for disbond, cracks and porosity defects. The work focuses on the inspection of the track shoe center spline where MMC inserts are attached to the aluminum substrate. A hybrid approach has been developed where an array of broadband high frequency ultrasonic transducers operating in a pulse/echo mode are utilized to detect disbond, and a scanning eddy current probe array is used to detect cracks and porosity. The Inspection results agree quite well with immersion ultrasonic C-scan images and destructive tests.