Study Of Dynamic Characteristics Of Bladed Disk With Breathing Crack

Bladed disk is a key component of bearing rotor system of gas turbine. Because of the bladed disk often is in high temperature and high pressure, high speed of extreme service environment, which lead to turbine blade caused failure easily in bladed disk. In practical engineering, as a result of material defects, manufacturing tolerance and stress concentration, resulting in crack fault is one of the most common damage of engineering structures, which severely threatens the integrity and security of the blade-disk. However, studies on bladed disk containing cracked blade does not fully take into account the breathing behavior of fatigue crack in continuous vibration exciting until now, which cause nonlinear problems are less involved. Aiming at practical problems in project, the vibration localization and nonlinear dynamic characteristics of bladed disk with breathing crack were analyzed.Firstly, Comprehensive consideration to nonlinear breathing behavior of the fatigue crack, a more objective breathing cracked fitting model were established based on a variety of theories. The natural frequencies belonging separately to bladed disk with open crack and bladed disk with breathing crack were compared, and it is proved that open crack model could caused crack fault diagnosis method based on change of natural frequency appears to misjudgment.Secondly, based on a continuous parameter of bladed disk with breathing crack, the vibration response characteristics of bladed disk with open crack and bladed disk with breathing crack were compared, and the effects of breathing crack to vibration response localization of bladed disk were researched.Finally, the effects of breathing crack on nonlinear dynamic characteristics of bladed disk were analyzed. The results show that breathing crack could cause forced vibration response of bladed disk to appear the complicated nonlinear characteristics, such as unbalance response, resonant frequency shift, and harmonic resonance. It can be seen that the dynamic model of bladed disk with breathing crack and numerical statistical method is crucial to practical application of the quantitative crack identification techniques, thus it is to provide easy identification of sensitivity parameter on fault diagnosis, online monitoring of fatigue crack.The outcomes of this dissertation develop and complete the fundamental theory of global dynamic characteristic of bladed disk. And they can be a theoretical support for dynamic optimum design, reliability analysis, fault diagnosis and mechanism of bladed disk.