Experimental Study And Analysis Of The Endurance Properties Of Directionally Solidified Turbine Blade

Turbine blade which is the key component of engine turbine rotor system works under abominable conditions of centrifugal force and its moment, pneumatic force and its moment, high temperature and vibration. So the turbine blade is called the bright pearl of the crown, its life determine the life of turbine engine directly. In order to improve the reliability of design parameters and endurance life design method of turbine blade, an accurate prediction and estimation of turbine blade's life is needed imminently. This paper studies the endurance properties of turbine blade material by experimental study and theory analysis under the background of one aviation science fund's need.Firstly, according to the shape of the specimen and experimental load type which the standards prescribe, the shape and the size of specimen are designed with material mechanics. And the jig is designed for specimen's machining according to the shape of real turbine blade and the location of specimen material on the turbine blade. Then the turbine blade is machined on the numerical control machine tool and experimental specimens which have the equal work character with the real blade are achieved, and the real size of the specimen is measured.Secondly, experiment of endurance life is performed. Specimens are loaded on the MTS810 hydraulic server material experimental machine according to the endurable strength of standard specimen. The real endurance life of specimen is gained , at the same time the process data of specimen's creep is achieved through placing two transducers separately under and upon the experimental machine. Endurance life of standard specimen under the same nominal stress is given to be compared with the experimental result.Finally, the experimental data of standard specimen is regressed withθ-Concept Project and Norton creep parameters are achieved, then the specimen is modeled and analyzed with finite element software and the stress distribution of specimen is obtained. According to endurance life equation of standard specimen, the endurance life is predicted through computing the max stress on the minimal section of the specimen with finite element method and it will be compared with the experimental result and endurance life of standard specimen under nominal stress and analyzed. Through experimental study it is found that the endurance life of specimen achieved from the real blade is shorter than the endurance life of standard specimen, the endurance life of specimen with hole is much shorter. Through finite element analysis of the specimen with hole, it is presented that the holes on the specimen change the distribution of specimen's stress, make the max stress centralized around the hole, and reduce the endurance life of specimen obviously. So it's not safe to design turbine blade using the date of standard specimen directly, in the process of turbine blade structure design, the film cooling holes should be paid more attention.