Fatigue crack initiation and vibration prediction life of turbine blade

The objective of this work is to present a model of high pressure turbine blade, made of single crystal superalloy based on nickel. Their leading edges may be privileged sites of damage and crack initiation it is necessary to take into account in the manufacturing of turbine blades. This work consisted, initially to make a theoretical study, the turbine blade is modeled as a Timoshenko rotating beam . In a second step we made a numerical approach to study the effect of crack initiation on natural rotating frequencies, and the effect of cycle number on rigidity. The dynamic showed the variation of mechanical properties under crack propagation. In general, these changes in addition to initial defects of the material structure favoring the spread of cracks under isothermal loads. Finally an experimental study of the fatigue crack growth and the influence on the blade vibration is presented. This helped to highlight mechanical damage and determining the fatigue life predictive of component.