Machinery & Energetics

In this paper, the statistical characteristics of scattering of energy of elastic oscillations according to dispersion parameters of measured phase shift of stresses of wave of elastic deformations locally initiated in contact area with the surface layer of the waveguide metal of the resonant vibrational electromechanical system were estimated. The method allows to reveal the regularities of accumulation of scattered damage of the design element for the operational loading, using the methodological approaches applied in the work to the laboratory samples of steels and alloys as model objects of metal structures. It is established that the decrease of the dispersion of discrete inelasticity causes the strengthening of structural material, and the growth-strengthening. The cyclicity of the kinetics of inelasticity is found not to depend on the amplitude of the stresses of the cycle and manifests the stochastic regularity. For the analysis of the experimental sequence obtained, a recurrent formula characterizing the evolution of the energy state prior to the destruction of the local volume of polycrystalline material, which is based on the energy of universal sustained destruction, is used. On the basis of the proposed method, it is established that the number of loading cycles N₁ corresponds to the state of the structural material of the first point of the bifurcation. The following values (N₂, N₃, N₄, N₅, N₆) of the number of cycles are calculated, correspond to certain points of bifurcations in the diagram of accumulation of fatigue damage according to discrete measurements, which allows predicting the durability of the destruction of the surface macrocrack of the sample. The proposed approach to the analysis of the characteristics of scattered damage on the basis of the local properties of the inelastic structural materials retains the advantages of direct methods for investigating the resistance of the fatigue material of laboratory samples and creates new possibilities for determining the current state of the degree of damage to the structural element.

fatigue, inelasticity, scattered damage, microplastic deformation, bifurcation points