Model and Method for Calculating Cyclic Damageability under High-Frequency Loading of Corset Samples
I. S. Nikitin, A. D. Nikitin, B. A. Stratula
Institute of Computer Aided Design of the Russian Academy of Sciences, Moscow, Russia
Keywords: ultra-high-cycle fatigue, vibrations of alternating rods sections, perturbation theory, high-frequency tensile-compression tests, cyclic damage
Abstract
Using previously obtained analytical formulas for the natural frequencies and vibration modes of inhomogeneous rods with a variable cross-section (corset shape), the geometric and elastic characteristics of the samples were determined, and the amplitudes of axial stresses obtained during experimental studies of the fatigue strength of metal alloys under high-frequency cyclic loading were assessed. Based on a three-mode model of fatigue failure, a numerical method is proposed for calculating the kinetics of damage under high-frequency cyclic tensile-compression loading of corset-shaped specimens at different values of the cycle asymmetry coefficient. The results of calculations using the proposed model are compared with the results of experiments on corset-shaped samples made of titanium alloy. The proposed model and calculation method make it possible to construct fatigue curves with sufficient accuracy for various cyclic loading modes and cycle asymmetry coefficients. To do this, it is enough to know the base points of the bimodal fatigue curve for the reverse cycle.
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