When a structure is subjected to damage, it is obvious that the modal parameters will change because the damage reduces the structure's stiffness. Considerable effort has been taken in the last few years regarding investigation of the relationship between the damage location, the damage size and the corresponding shift in eigenvalues and the change of eigenvectors. In this paper, a systematic study of analysis and experiment was made on correlating the crack of the beam with changes in modal parameters. For each modal parameter (for example, natural frequency, displacement mode and displacement eigenparameter, and strain mode and strain eigenparameter) the sensitivity to both crack location and crack size has been developed. A new type of finite element model in which fracture theory was applied to a vibrating cracked beam was developed to provide data for analysis. In the experiment, the crack was extended by a fatigue load and modal parameters were obtained by time domain identification technique. The results obtained from the calculation and experiment coincide well.
展开▼
