Overview of System Identification and Case Studies Using Vibrational Techniques

In the field of non-destructive evaluation and damage detection, there is continued interest in the utilization of vibrational techniques. Structural damage will result in permanent changes in structural stiffness, distribution of stiffness, and relevant material properties. These changes may be detected by monitoring dynamic behavior of the structure. Because of the direct relationship of mass, damping, and stiffness of a multi-degree-of-freedom system to the natural frequencies, mode shapes, and modal damping values, many studies have been directed at using these properties for the purpose of structural health monitoring. The use of vibrational monitoring is very valuable in some cases, and is capable of assisting in both detecting and locating structural damage. Vibrational data is most useful when used in conjunction with other monitoring if a remote and robust damage detection scheme is desired. This paper includes a literature review and discussion of the basic approaches to vibrational monitoring, suggested guidelines for sensor selection and monitoring, and concludes with examples of two case studies.