呼吸裂纹的非线性虚拟激励识别方法研究

Breathing cracks arc a common type of local nonlincar damage, such as fatigue cracks and de-lamination damage, whose "breathing" effect causes cyclic changes in the local structural stiffness, which inercases the difficulty of damage characterization. Traditional damage identification methods based on nonlincar Vibration characteristics are difficult to accuratcly locatc and quantify local breathing cracks due to limited measurement information. With the dcvelopment of full-field Vibration displacc-ment measurement technology, the Vibration displacement field on the surface of platc strueturcs can be rcadily obtained, which brings new opportunities for the aecurate identification of breathing cracks. In this paper, a nonlinear pseudo-excitation based method is proposed to localizc the "delamination-type" breathing crack in plate struetures by combining the Vibration displacement field information and the local dynamic cquilibrium. The method firstly performs feature extraction and efficient nonlincar feature Parameter identification of the Vibration displacement field by construeting orthogonal basis funetions, and then calculates the nonlincar pseudo-excitation by using the identified super-harmonic frequencies and their characteristic deflection shapes in Order to realize the high-precision localization of breathing cracks. Finally, thc correctness of the proposed method is verified by a thin plate structure with "dclam-ination-typc" brcathing cracks.