Damage identification of tube bundles with crack subjected to cross-flow and loose support

Dynamic characteristics of tube bundles with crack subjected to cross-flow and nonlinear loose support are very complicated, making the damage identification more difficult, and the information of healthy tube bundles could not be used in the damage identification process. In this paper, a baseline-free damage detection method is proposed to detect the crack damage of tube bundles subjected to cross-flow and loose support. Two damage indexes, based on the root mean square value of structural vibration responses and the gapped smoothing method, are proposed to identify the damage location and damage extent. Cases with different damage locations and damage extents are considered. The influences of the flow pitch velocity, loose support and the number of measure points on the effectiveness of the method are also discussed. The results showed that the index based on the normalized values of root mean square displacement and velocity responses can identify the damage location accurately within the flow pitch velocity range considered in this study. An improved index based on the normalized values of root mean square displacement and velocity responses and a parameter reflecting damage extent can identify the damage extent when the flow pitch velocity is small. When the flow pitch velocity is large, the effectiveness of the improved index is affected. Meanwhile the loose support location also has an influence on the proposed method, especially when the flow pitch velocity is large. Number of measure points has little influence when the damage extent is larger than 5%