AN ULTRASONIC METHOD FOR EVALUATING BONDS IN LARGE METALLIC BEARINGS.
PACIFIC NAVAL LAB ESQUIMALT (BRITISH COLUMBIA)
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This paper describes an ultrasonic method for evaluating the quality of bonds in large metallic bearings. The study was initiated after an examination of a number of failures of large main bearings indicated that the babbitt and steel were only partially bonded. The method of evaluating the bonds consists of applying a 2.5 Mc double-transducer probe to the babbitt, and comparing the relative intensities of two reflected signals, one due to transmission through the interface, and the other due to reflection from the interface. The greater the relative strength of the signal transmitted by the interface, the better the quality of the bond. A correlation is made between the amplitude relationship of the ultrasonic signals and the approximate percentage bonding in a number of experimental bearings. It appears that the method could be utilized for evaluating bonds in actual bearings, provided that the bearings were quite large and that the steel backing was not notched or grooved. Author