Crack identification in vibrating beams using the energy method

An energy-based numerical model is developed to investigate the influence o f cracks on structural dynamic characteristics during the vibration of a be am with open crack(s). Upon the determination of strain energy in the crack ed beam, the equivalent bending stiffness over the beam length is computed. The cracked beam is then taken as a continuous system with varying moment of intertia, and equations of transverse vibration are obtained for a recta ngular beam containing one or two cracks. Galerkin's method is applied to s olve for the frequencies and vibration modes. To identify the crack, the fr equency contours with respect to crack depth and location are defined and p lotted. The intersection of contours from differerit modes could be used to identify the crack location and depth. (C) 2001 Academic Press.