NUMERICAL SIMULATION OF HIGH-TEMPERATURE CREEP OF ELEMENTS OF HEAT-RESISTANT ALLOYS STRUCTURES TAKING INTO ACCOUNT NEUTRON IRRADIATION EFFECTS

The technique of numerical research on the basis of FEM processes of deformation and damage accumulation in the structural elements of heat-resistant alloys under conditions of high-temperature creep taking into account the influence of neutron irradiation is developed. The description of the mechanical behavior of the material is carried out within the framework of the previously developed general model of the damaged material and the creep model for non-irradiated heat-resistant alloys, supplemented by taking into account the effect of irradiation on the creep rate and the appearance of brittle fracture in a given range of temperature variation and irradiation intensity. The defining relations of the creep model of the irradiated material were obtained by modifying the creep model of the non-irradiated material: a material function was introduced, taking into account the effect of the flux of neutrons on the rate of thermal creep deformation; a material function was introduced that takes into account the effect of the neutron flux on the creep surface radius; A material function was introduced, which takes into account the effect of the neutron flux on the ultimate value of the dissipation energy at full power. To simulate the processes of brittle fracture during creep under neutron irradiation conditions, it is assumed that the destructive values of effective normal stresses are a function of temperature, flux of neutrons and the current value of accumulated creep. The material functions of the model were obtained from the results of basic experiments conducted at the Research Institute of Mechanics for the heat-resistant alloy without irradiation under consideration and the available experimental data on the study of the creep of this alloy during its irradiation. Based on the proposed model, a numerical method for solving problems of high-temperature creep of structures made of heat-resistant alloys under neutron irradiation was developed and implemented within the UPAKS computing complex. To verify and illustrate the capabilities of the developed methodological and software tools, a number of problems of modeling the processes of high-temperature creep and destruction of structural elements made of the high-temperature alloy under consideration are solved.