A baseline-free damage detection method based on node displacement in mode shape
Abstract »Most widely studied SHM methods need baseline data at undamaged stage and a high number of sensors attached to the structure, which make these methods hard to be applied in aircraft structures for online monitoring. The idea of this paper is to determine a practical damage indicator based on the mechanical information in structural design. In this paper, a new parameter called node displacement is proposed from the area of mechanical vibration. In the mode shape, the displacement at the node is always zero according to definition. When damage appears on the structure or the structural stiffness is changed, the displacement at the original node will become nonzero. The advantages of this method are: (1) baseline-free, (2) only small number of sensors is required. Parameter studies of damage location are analyzed by FEM. An experiment conducted on a beam together with a transfer function based damage index demonstrates the advantage of this method. In addition, the influence of noise, damage sensitivity, and the influence of sensor location are discussed.