Crack Detection in Simply Supported Beam Using Vibration Response

摘要

Cracks are always hidden risks in engineering structures especially in marine, aerospace, ground and civil. Under fatigue load operating conditions, the cracks may be produced as a result of the inherent flaws in the material. Most of the failures of present structures are caused by operating in these service conditions for too long a time. For this reason, methods for making early detection and localization of cracks possible have been the subject of recent investigation. Crack detection in engineering structures using dynamic system parameters has become an important area in research. A reliable, time and cost effective method is therefore required to evaluate and localize crack using the changes in dynamic parameters between the uncracked and cracked states. In the present work, a methodology for predicting crack parameters (crack depth and its location) in a thin simply supported beam using vibration response has been developed. Parametric studies have been carried out using ANSYS Software to evaluate modal parameters (natural frequencies and mode shapes) for different crack parameters. From the analysis, it has been observed that both crack location and crack depth have noticeable effects on the modal parameters of the cracked beam. Also, a certain frequency may correspond to different crack depths and its locations. Based on this, the contour lines of the cracked beam frequencies have been plotted having crack location and crack depth as its axis. The location and depth corresponding to any point on this curve becomes a possible crack location and depth. The identification procedure presented in this study is believed to provide a useful tool for detection of medium size crack in a beam.