A.D. Nikitin - Post-graduate Student, Department of Physics, MATI - Russian State Technological University. E-mail: nikitin_alex@bk.ru I.S. Nikitin - Dr. Sc. (Phys.-Math.), Professor, Department of Physics, MATI - Russian State Technological University; Leading Research Scientist, Institute of Computer Aided Design of the Russian Academy of Sciences (ICAD RAS). E-mail: i_nikitin@list.ru

Many elements of aircraft structures are subjected to low-amplitude vibration loads during operation. Acting for a long time vibrations can cause the destruction of structures. It is important to note that the stress amplitude can be substantially lower than the fatigue limit for the long years of operation and at all should not pose a danger according to the classical point of view. However, fatigue fracture occurs even for long time continuous operation of structure below fatigue limit (very-high-cycle fatigue VHCF). Therefore, in addition to the classic modes of low-cycle and high-cycle fatigue of metals, it is necessary to investigate the mode of very-high-cycle fatigue. Also, fatigue crack nucleation mechanism is radically changed under low amplitude loads for VHCF mode. In this paper the ineffectiveness of existing fatigue test methods for materials research is discussed in the area of very-high-cycle fatigue. A method for testing of metallic materials is described using piezoelectric elements. The prototype of high-frequency fatigue equipment is discussed in detail. The results of some VHCF fracture experiments are represented for the samples of titanium alloy VT-1.

 

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