Ultrasonic control of bolt tightening

Details Ultrasonic control of bolt tightening Ultrasonic control of bolt tightening

2008-04-22

2008-04-22

Lefkowitz, Edward (Department: 2855)

Measuring and testing

Specimen stress or strain, or testing by stress or strain...

Threaded fastener stress

C702S039000, C702S159000

Reexamination Certificate

active

11316557

ABSTRACT:
Tightening of a bolt is controlled by monitoring the change in round trip time of propagating longitudinal ultrasonic waves through the bolt and the reflection of these waves at the end of the bolt. The round trip time of the longitudinal waves through bolt is continuously measured and monitored in real-time. Elongation of the bolt as it is being tightened is determined based on the change in the round trip time of the longitudinal waves, which provides the level of bolt tension and joint clamp load. In determining the bolt elongation, an elongation-dependent wave speed has been formulated and used in-real time. When the elongation of the bolt reaches a predetermined level, tightening is automatically stopped.

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