METHOD FOR CALCULATING THE CREEP STRAIN OF A MATERIAL
The structure under prolonged loading during operation is subject to the phenomenon of creep, which can affect its performance. This effect depends on the load level, duration of loading, operating conditions, design features, and type of material. All these factors are taken into account when testing to obtain creep curves for a specific material and various external conditions that correspond to the operating conditions of the structure. These curves allow us to construct a mathematical model of elastic-plastic deformation of the material. The model proposed in this paper is based on the analysis of various hypotheses of the material creep process. In particular, we considered: · the flow hypothesis, in which the main factor determining the creep rate is the time spent under load at a given temperature; · the hardening hypothesis, in which the main factor determining the creep strain rate is the strain caused by the presence of active loads; · the relative durability hypothesis, which is a combination of the flow hypothesis and the hardening hypothesis. This analysis allows us to estimate both the magnitude and rate of creep deformation, and the effect of creep deformation on the stress-strain state of the material. As an example of using the proposed method, a cylindrical shell under axisymmetric loading is considered.