| 摘要 |
A system is employed for measuring the changes in velocity of ultrasonic waves in structural members as a result of variations in local elastic stresses about fastener holes. In a first embodiment, piezoelectric transducer and detector members are employed while in a second embodiment non-contacting laser transducer and detector components are used. The invention is capable of detecting the establishment of optimum cold working around a fastener hole by monitoring the velocity of ultrasonic waves in the structural material. This ensures maximized useful life of the structural member by avoiding over or under worked fastener holes.
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