Using the Random Decrement Method for the Decentralized Acquisition of Modal Data

Structural health monitoring methods based on modal properties are well suited for infrastructure objects, e. g. bridges or wind turbines. The size of these structures leads to a large number of sensors to be placed and long distances between them and the signal processing units. To save cabling effort, a communication via bus can be used. To realize this, the amount of data to be transmitted should be reduced by a network of smart sensors. This paper discusses a strategy for decentralized signal analysis with the Random Decrement method and Operational Modal Analysis. After a description of the Random Decrement method, the application in decentralized data acquisition is illustrated with a numerical example. Thereafter, a simple experimental structure exposed to wind loads is used to test the data acquisition in reality. By automating the process of modal decomposition, the described network is capable of acquiring the development of the eigenfrequencies and modeshapes over time. This is the input needed for structural health monitoring applications.