LABORATORY SETTING FOR TESTS OF STANDARDS ON TIREDNESS BY MEANS OF BIHARMONIC LADENING

The situation when the metal structure is subjected to the simultaneous impact of two or more sources of simple stress is common in mechanical engineering, aviation and civil engineering. The fatigue life of the material by the impact of Biharmonic loading is 1.5‒4 times lower than in single-frequency operation loading. Unlike the single-frequency loading under Biharmonic loading degradation of the material is accelerated because of the intensification of the process of fatigue damage accumulation. Description of the process of damage accumulation of fatigue in the material under biharmonic loading is closer to the real situation. The aim of the workis ‒ to create an effective setting for testing of ferromagnetic samples for fatigue and durability. To achieve the objectives small-sized laboratory facility for testing ferromagnetic sample flexural fatigue developed and produced. Studies have been conducted using the method of magnetic Barkhausen effect. The article describes the design and its basic characteristics, as well as the basic technical characteristics the sample. The principle of operation is based on the bi-harmonic load acting on both ends of the sample. The device use two electric motors with two special agents of power, based on the use of rolling bearings. Installation and testing of samples by the method of independent regulation of dual-frequency cyclic loading allows to simulate the condition of the test sample in the approximation to the real working conditions. This allows a detailed investigation of fracture toughness of the material, the stages of fatigue crack propagation and identify new patterns of development of fatigue. Unlike analog unit has small dimensions and weight (the length of the sample does not exceed 20 cm, width – 13 cm, height – 25 cm, weight of the unit is 12 kg). Use of the setting can improve performance and reliability of tests in two times.

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