A set of experimental results concerning the accumulation of inelastic strain in the VT6 titanium alloy is presented. The considered tests include cyclic stress-controlled loading with monotonically increasing stress amplitude and constant mean stress. The focus of the study is on the accurate phenomenological modelling of the complex material behaviour. Four different material models are employed to capture the phenomena of ratcheting and nonlinear kinematic hardening. Two models are of the Armstrong-Frederick type and the remaining two models are of the Ohno-Wang type. Since all the considered models contain a big number of material parameters, a sophisticated nested procedure is used for the parameter identification; the obtained material parameters are validated by additional experiments. It is shown that all the models yield nearly the same accuracy; the limitations of the phenomenological approach are highlighted and discussed.

One of the tasks of modern material science is to obtain new functional high-strength resistant coatings on structural materials like aluminum alloys. This paper shows the effect of plasma electrolytic oxidation (PEO) on the fatigue strength of V96Ts1 (Al-Zn-Mg-Cu) aluminum alloy. Fatigue tests were carried out with uniaxial loading in accordance with the harmonic law with a constant stress of 205 MPa. The modification of the PEO-coated surface layer led to a 5-fold decrease in the cyclic durability of the V96Ts1 alloy. The dependencies of the temperature of dissipative heating and the accumulated strain on the amplitude of the effective load were obtained for the inelastic cyclic strain of V96Ts alloy samples, with and without a PEO-coated surface layer. These dependencies describing material degradation correlate with the data of the fatigue tests. A fractographic analysis of the destroyed samples was also performed.

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