A nonlinearity evaluation based crack location identification for cantilever beam-like structures using different excitation force levels

Nonlinear characteristics may arise in its forced responses in vibrating structures with inherent nonlinearity. A breathing crack can manifest itself as a structural nonlinearity in cantilever beam-like structures, and its influence on nonlinear effects can not be negligible. Then, measuring the changes of nonlinearity severity of forced responses is an alternative means to detect the cracks in cantilever beam-like structures. In this paper, a nonlinearity evaluation based identification method is proposed for crack location of beam-like structures using different excitation force levels. The vibration responses under the low/high force level ex-citations are collected on the damaged beam-like structures, and the distortions of the frequency response functions (FRFs) is used to denote the extent of nonlinearities. The crack location can be identified by searching the maximum values in the vector of damage indices, which is obtained by evaluation for the distortions of FRFs. The vibration experiments are conducted to verify the effectiveness of this approach, in which cracks are designed to create the open-close effects in the forced responses of the bamboo beams.