Vision-based vibration mode shape extraction for identifying cracks in a cantilever beam

Abstract

Taking significant merits of high spatial resolution of image sensing, the vibration mode shape of a cantilever beam (CB) is obtained from the free vibration process for local crack identification and structural health monitoring. This vision-based vibration measurement uses a cost-effective rolling shutter camera and a computationally efficient singular value decomposition (SVD). It shows that vibration modes of a continuous structure such as a CB are mainly determined by spatial resolution and less rely on temporal resolution. Moreover, images recorded by the camera maintain the critical information about mode profiles though distortions are introduced into the image. Decomposing the images by SVD allows the vibration modes to be extracted with good degree of accuracy. Both simulation study and experimental verification shows that this novel approach allows different sizes of cracks and locations to be identified.