Use of operational deflection shapes for structural damage detection

Damage detection can increase safety, extend serviceability, reduce maintenance costs, and define reduced operating limits for structures. Vibration-based methods are new approaches being investigated to detect damage in various types of structures. These methods are considered to be more globally sensitive to damage than localized methods such as ultrasonic and eddy current methods. However, the interpretation of vibration responses to identify damage is challenging, and the degree of the success of the methods is dependent on the numbers and types of sensors and actuators applied. One technique that is promising is the use of Operational Deflection Shapes (ODS) for structural damage detection. The ODS are the actual vibration displacement or velocity patterns of a structure that is responding in the steady-state condition to a specific structural loading. In this paper, the ODS are represented as summations of scaled mode shapes and it is demonstrated how ODS can be used to identify structural damage. Generation of experimental ODS is performed using a scanning laser doppler vibrometer and a piezoceramic actuator, and examples of damage detection on a beam structure are presented.