Fatigue analysis of the compressor blades with V - Notches

Abstract

This paper presents results of experimental and numerical fatigue analysis of damaged compressor blades, subjected to vibration. The blades used in experimental investigations were preliminary defected to simulate the foreign object damage. The crack propagation process was conducted in resonance condition. During the fatigue investigations, the crack length and amplitude of the blade tip displacement were monitored. The main result of experimental test is the crack growth rate obtained for the blade including V-notch. In the second part of work, the results of the complex stress and fatigue analysis for the helicopter turbo-engine compressor blades were presented. A nonlinear finite element method was utilized to determine the stress state of the blade during the first mode of transverse vibration. In this analysis, the numerical models without defects and also with V-notches were defined. Obtained results were next used as an input data into crack initiation (ε-N) analyses performed for the load time history equivalent to one cycle of the transverse vibration. As a result of ε-N analysis, the number of load cycles to the first fatigue crack appearing in the compressor blade was obtained. Moreover, the influence of the blade vibration amplitude on the number of cycles to the crack initiation was analyzed. The numerical results were compared with the results of an experimental high-cycle fatigue (HCF) tests performed for the first stage compressor blades.