A model of damaged media used for describing the process of non-stationary creep and long-term strength of polycrystalline structural alloys

The main laws of the processes of creep and long-term strength of polycrystalline structural alloys are considered. From the viewpoint of continuum damaged media (CDM), a mathematical model is developed that describes the processes of viscoplastic deformation and damage accumulation under creep. The problem of determining material parameters and scalar functions of the developed constitutive relations based on the results of specially set basic experiments is discussed. An experimental–theoretical methodology for determining material parameters of the derived constitutive relations of CDM is developed based on analyzing the viscoplastic deformation and failure processes of laboratory specimens in the conditions of soft loading (stress controlled). Experimental results of short-term creep of the VZh-159 heat-resistant alloy are presented. The obtained numerical results are compared with the test data using the numerical modeling method of experimental processes. Qualitative and quantitative agreement between numerical results and experimental data is shown. It is concluded that the developed constitutive relations are reliable, and that the proposed methodology accurately determines the material parameters of the model under degradation of initial strength properties of structural materials according to the long-term strength mechanism.