A novel couplant free mediator ultrasonic rayleigh wave technique for detecting surface cracks in green parts

Surface cracks initiated by handling and production issues in green parts affect the final integrity of a sintered part. The subject of crack detection in green parts has been of significant interest for decades with no real solution being available until recently. Despite the abundance of applicable techniques for inspecting sintered parts, green part inspection techniques are restricted. Some promise has been recently demonstrated with visual and resonance techniques; however the success of these methods is limited. Presented here is a novel surface wave approach based on the use of a couplant free mediator. Surface wave techniques are presented as an economical and reliable alternative to current nondestructive inspection methods. Design of a test setup for analyzing the applicability of surface wave techniques to detect cracks in specific orientations in green parts is provided. Surface wave generation techniques in conjunction with design considerations of such a system will be demonstrated. Surface wave response evaluation theories, such as amplitude and Fourier analysis methods for detecting and characterizing flaws are discussed and demonstrated through physical testing of samples. Specific applications relative to the automotive and other industries are presented to demonstrate the ability of the techniques to characterize surface defects in green parts.