음탄성법을 이용한 고장력 볼트의 축응력 평가

초록

evaluation of clamping condition has been regarded as the main issue in the safety-maintenance of the clamped high-tension bolts. For this, this paper proposes a method to estimate the axial stress by measuring the TOF (Time-Of-Flight) of ultrasonic wave, which is based on the acoustoelasticity or the dependency of sound speed on the stress. In this method, however, the variation of sound speed within the range of stress induced under the field condition is very small, and thus the accuracy of the TOF measurement is important. We adopted the phase detection method using tone-burst ultrasonic wave to measure the precise TOF. In order to verify the usefulness of the proposed method experiments are carried out and the results were compared with the stress measured by the strain gage. The results show good agreement with each other, and from these we can conclude that the proposed method is highly useful for the evaluation of clamping condition in the clamped high-tension bolts.

키워드