266 / 2021-04-15 19:12:21

Vibration characteristics of the blisk with fatigue crack and effect of damping coating treatment

Vibration characteristics,Blisk,High-cycle fatigue,Blade crack,Damping coating

Special Sessions > Mechanical dynamics

Failures due to high-cycle fatigue have led to high cost in aerospace engineering over the past few decades. As a new form of structure, the low intrinsic damping capacity of blisk makes it suffer more seriously from the vibration fatigue than the bladed disk with tenon joint. In this paper, firstly the fatigue characteristics of blade subjected to resonance were investigated by experiment. The crack initiation and propagation processes were observed under resonance of the first bending mode, by using the resonant frequencies as the indicator. Significant nonlinear features were observed in the spectrum of the blade with a fatigue crack. Then the finite element model considering the breathing crack was established with nonlinear contact based on the crack localization and size, which was obtained by ultrasonic phased array technology. The simulation results of the vibration behaviour of the cracked blade were obtained and consistent with the experimental results. Further, reduced-order model of blisk with cracked blade was established, based on which the mistuned vibration characteristics and responses of blisk under various engine orders of excitation were researched by numerical simulation. At last, a damping coating was deposited on the blades, and increases of the fatigue life were observed under the same condition. The results of this paper can help to better understand the fatigue and crack of blade and provide a preference for the application of a damping hard coating on blades.