Vibration analysis and crack identification of a rotor with open cracks

摘要

A finite element model is used for flexural vibration analysis of a static (non-rotating) rotor with open cracks; the stiffness matrices of the cracked elements are obtained using transfer matrix analysis and local flexibility theorem. Through numerical simulation, the effects of the slenderness ratio and the crack depth on the mode shapes and the changes in the eigenfrequencies of the cracked rotor are investigated; the variations of the changes in eigenfrequencies with crack location are studied; and the ratios of the changes in the first two eigenfrequencies are discussed for rotors with two cracks. Then, crack identification algorithms for one unknown crack case and for two unknown cracks case are proposed, and illustrative examples are demonstrated to verify the validity of the proposed algorithms.