Fatigue life prediction of welded joints using a small wireless monitoring device

Abstract

This paper examines the applicability of the hot spot method using a small wireless system and the effect of data loss during data communication on fatigue evaluation. It is not practical to monitor all structural members, it is important to monitor the structural integrity of damage-prone areas. In addition, due to cost and installation space constraints, the use of inexpensive, compact IoT devices is effective. Small wireless fatigue monitoring methods using strain gauges have been proposed, and systems based on the nominal stress method have been considered. However, there are cases where the nominal stress cannot be defined due to the complex structure of the weldment. In such cases, the hot spot method, which measures the structural stress concentration, is effective. However, the application of the hot spot method to a small wireless monitoring system has not been sufficiently studied. In this paper, a small wireless monitoring system was fabricated and its applicability to fatigue evaluation of welded joints was confirmed. From the test results, it was confirmed that the data loss was caused by the data communication condition of the small wireless system and the accumulated fatigue damage degree was underestimated. It was also confirmed that an appropriate small wireless monitoring system should be selected considering the information on fatigue and stress conditions required for the target structure.