Laser ultrasonics applied to surface and subsurfacic flaws detection in sphere, example of c-crack detection in nitride ceramic bearing balls

VANHOYE, Arnaud; CEA LIST; France

Vanhoye, A.; CEA; France
Bredif, P.; CEA; France
Schweitzer, L.; Safran Aircraft Engines; France

ID: ECNDT-0318-2018
Download: PDF
Session: Laser UT 2
Room: J1
Date: 2018-06-14
Time: 10:50 - 11:10

The generation and detection of ultrasound using laser is not widespread in industry as it remains a costly technology while constraining due to security aspects. However, it constitutes one of the only efficient means to generate ultrasound contactless, and is thus well suited for very specific applications such as hot piece inspection or complex geometry inspection. Contactless generation and detection is also a major benefit for surface waves applications, as the detection measurement will not alter the wave propagation phenomena.

Based on theses assets, an inspection method dedicated to surface and subsurface flaw detection in spherical elements such has bearing balls is proposed. The method uses the propagation of Rayleigh waves confined to the sphere equator and extracts flaw signature thanks to a specific signal processing algorithm. The method is a potential solution for the inspection of ceramic bearing balls, which is of crucial importance for aeronautic industry as they ensure the proper functioning of jet engine.

The developed method is evaluated for the detection of c-crack, critical bearing balls notches of a few hundred micrometers long, less than 1µm wide and forming an arc. Results on nitride ceramic bearing balls are presented.