Acoustic Emmision Characteristics according to Failure Modes of Pipes with Local Wall Thinning

J. Ocean Eng. Technol. 2002;16(5):66-72.

감육배관의 손상모드에 따른 음향방출 특성

안석환,남기우,김선진,김진환,김현수,박인덕

부경대학교 기계공학부,부경대학교 재료공학부,부경대학교 기계공학부,부경대학교 대학원 재료공학과,부경대학교 재료공학부,부경대학교 재료공학부

Keywords: Local Wall Thinning, Bending Load, Failure Mode, Acoustic Emmision, Time-Frequency Anlysis, Pip

핵심용어: 국부감육, 굽힘하중, 손상모드, 음향방출, 시간-주파수분석, 배관

Abstract

Fracture behaviors of pipes with local wall thinning are very important for the integrity of nuclear power plant. However, effects of local wall thinning on strength and fracture behaviors of piping system were not well studied. Acoustic emission(AE) has been widely used in various fields because of its extreme sensitivity, dynamic detection ability and location of growing defects. In this study, we investigated failure modes of locally wall thinned pipes and AE signals by bending test. From test results, we could be divided four types of failure modes of ovalization, crack initiation after ovalization, local buckling and crack initiation after local buckling. And fracture behaviors such as elastic region, yielding region, plastic deformation region and crack progress region could be evaluated by AE counts, accumulative counts and time-frequency analysis during bending test. The result of the frequency range is expected to be basic data that can inspect plants in real-time.