Damage Identification of CFRP Laminated Beam by the Natural Frequency Change Using Response Surface Methodology

Recently, FRP composite structures have been applied to many structures of vehicles. Damage, such as delamination, by an accidental impact causes stiffness degradation of the structures. Since the damage is interior and invisible from the outside, it is important to inspect the damage by nondestructive inspection. In the present study, we propose an identification method of delamination in CFRP laminated beam using the natural frequency change and response surface methodology (RSM). Response surfaces are used for approximation of the natural frequency change in delaminated CFRP beam. In order to identify the delamination, we make a performance function using response surfaces. By minimizing the performance function, we can predict the delamination position and length of the delaminated CFRP beam easily and inexpensively. As a result, it is shown that there are good agreement between actual and predicted delamination positions and lengths.