Model of Accumulation of a Cycle Fatigue Damage in the Multi-parametric Random Loading

The article describes the method of estimation of the fatigue life under the multi-parameter random loading. This type of loading occurs when the investigated structure is exposed to the complex load in the form of independent random processes. The processes of changing the stress tensor components in the hazardous area are independent random processes. The proposed method is based on calculating of the microplastic deformations. To calculate microplastics, the structural material model built on the description of the diagram of deformation dependence by the Bridge Ramber-Osgood is used. To identify the model of accumulation of damaged conventional, mechanical and fatigue properties of the material are used. The article presents the fundamental equations of the method. The method of accounting of the mean stress is proposed. The adequacy of the approach is confirmed by comparing the calculation results with the experimental data. Under uniaxial harmonic and random loading calculation results using the proposed model coincide with those obtained by traditional methods. In terms of the plane stress state, the difference between the calculated and experimental values of the experimental durability does not exceed 30% which is quite satisfactory for the case of a high-cycle fatigue.