In-plane vibration of circular annular disk for application to water pipe diagnosis

Abstract

Owing to aging of distribution water main, the accident such as leakage and explosion are occurring. To prevent above accidents, it is important to quantify the condition of water main by Non-Destructive Testing (NDT) and reflect it in renewal and repair plans. One of method to maintain the main efficiently, deterioration diagnosis method for distribution water main using the eigen frequency of in-plane bending mode in circular cylindrical shell is already suggested. The eigen frequency of in-plane bending mode is expected to have high accuracy in detection of deterioration, because the eigen frequency is proportional to pipe thickness. In actually water main is subjected to ground soil elastic force and water pressure in the inter-outer edge. However, in previous study, the effects of the edge boundary conditions were not considered. Thus, we focused on the annular disk model. The annular disk model is expected to expansion for modeling of the edge boundary condition. In this paper, the fundamental consideration of eigen frequency analysis of in-plane bending mode was conducted using annular disk model.