Method for detecting and sizing of cracks in bolt threads by rayleigh wave
AssigneesDong-man Suh, Keun-Sang Lim
InventorsDong-man Suh, Whan-woo Kim, Jin-gyun Chung
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Abstract
The present invention is a method of detecting and sizing of a small crack in a root between two crests in stud bolt threads. The key idea is from the fact that the Rayleigh wave is detected between large regularly spaced pulses from the thread. The delay time is the same as the propagation delay time of the slow Rayleigh wave and is proportional to the size of the crack. To efficiently detect the slow Rayleigh wave, three methods based on digital signal processing are proposed; modified wave shaping, dynamic predictive deconvolution, and dynamic predictive deconvolution, and dynamic predictive deconvolution combined with wave shaping.
Claims12
A method for detecting and sizing a crack in bolt threads, comprising the steps of:
- radiating an ultrasonic wave into the flank of the bolt threads with an incident angle other than 90 degrees;
- detecting a reflected signal, which is one of regularly spaced signals which are reflected from the threads;
- detecting a Rayleigh wave signal, which is from the Rayleigh wave propagating along the crack from the tip to the opening of the crack and reflected from the crack opening's mouth;
- measuring the elapsed time beginning from the reflected signal, and ending at the Rayleigh wave signal;
- and
- calculating the crack size by the elapsed time.
A method for detecting and sizing a crack in bolt threads, comprising:
- radiating an ultrasonic wave to the flank of the bolt threads with an incident angle other than 90 degrees;
- detecting a tip diffracted signal, which is diffracted from the crack tip;
- detecting a reflected signal which is one of regularly spaced signals which are reflected from the threads;
- measuring the elapsed time beginning from the tip diffracted signal and ending at the reflected signal;
- and
- calculating the crack size by the elapsed time.
Dependencies are inferred from the claim text.