Abstract
Reusable spacecraft is increasingly attracting researchers’ attention. However, the experimental investigations on the turbine blade of the rocket engine are rarely published. Thus, the fatigue of a small impulse rocket turbine blade is explored in the current work. First, the specimen and the electrode of electrical discharge machining are carefully designed. Then, the electrical discharge machining is used to machine the specimen. To study the fatigue properties, the finite element analyses are separately performed on the blade model and the specimen. Based on the numerical results, a fatigue test is carried out to reproduce the most vulnerable position. Finally, the microstructural structures of the specimen are detected using the scanning electron microscope (SEM). Results show that (1) different from the aviation field, the specimen is unable to be machined with the welding method because it destroys the crucial details and the mechanical properties; (2) the maximum plastic strain is present at the leading edge close to the hub, at which a 760 μm corner crack appears at the 10113th fatigue cycle. This work provides a feasible method of using the EDM process to machine specimen for the small impulse turbine blade.
Highlights
From the 1970s, the reusable space shuttle has been widely studied by the USA and the Soviet Union
To conduct the thermomechanical fatigue test on the single crystal turbine blade with the cooling hole, in 2013, Wang et al [2] developed a special test rig, by which the crack was successfully reproduced by using the heating and cooling subsystem to model the takeoff and shutdown stage in flight, respectively
There are two purposes to carry out the FEA for the specimen: (1) verifying whether the same maximum plastic strain is present at the corner of the leading edge and (2) obtaining the loads employed in the fatigue test
Summary
From the 1970s, the reusable space shuttle has been widely studied by the USA and the Soviet Union. As an advanced machining method, the EDM process is investigated in the current work to find whether it is suitable to prepare the small blade specimen. In the current paper, two methods, the welding and the EDM, are compared to process the specimen for a type of impulse turbine blade. Note the features are determined by the authors’ experience because the key problem in the investigation is to find the suitable method of machining the specimen but not to the optimal machining parameters. The feasibility of this processing method is supported by the finite element analysis, the microstructure detection, and the fatigue test
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