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Information × Registration Number 0224U031861, 0121U109857 , R & D reports Title Development of shape memory alloys functional properties prediction methods in systems of structures defense under dynamic loading popup.stage_title Head Yasnii Volodymyr P., Доктор технічних наук Registration Date 26-06-2024 Organization Ternopil National Technical University named after Ivan Puluj popup.description2 The modern designs of damping devices based on pseudoelastic SMA and the technical requirements for their design are analysed and determined. The literature review found that with an increase in the frequency of loading cycles under a strain-controlled mode, the stresses in each cycle increased, the dissipated energy decreased, and the residual stresses and the ability of the samples to deform remained almost unchanged until their fracture. Comprehensive studies of the effect of uniaxial tensile loading frequency on NiTi alloy's functional properties and low-cycle mechanical fatigue were carried out. Based on the results of fatigue tests of nitinol wires with a diameter of 1.5 mm under a stress-controlled mode and different frequencies of loading cycles f (from 0.1 to 10.0 Hz) with a stress ratio of 0.1, we obtained decreasing frequency dependences of the maximum value of dissipated energy, maximum and residual strain of specimens at the moment of fracture. It is shown that with an increase in the frequency of loading cycles from 0.1 Hz to 1 Hz, both εres of the specimens and the number of cycles before their fracture Nf decreased. At the same time, with an increase in f above 1 Hz, the Nf of the specimens increased against the background of a slight change in the residual strain. The constructed correlation between these indicators (εres - Nf) showed an ambiguous relationship between them with a kink at a loading frequency of 1 Hz. It was shown fractographically that, regardless of the frequency of loading of nitinol samples, their fatigue destruction occurred by the mechanism of fatigue pitting formation. At a loading frequency of up to 1 Hz, a new type of fatigue striations with a gradual change in pitch in the loading cycle was identified and described. Their appearance was explained by the occurrence of shear in the vicinity of the fatigue crack tip in different planes favourable for shear in martensite formed by direct and reverse phase transformations. Product Description popup.authors Antonov Andrii M. Brevus Vitalii M. Medvid Volodymyr R Okipnyi Ihor B. Student Oleksandra Z. Yasnii Petro V. popup.nrat_date 2024-06-26 Close