In modern mechanical engineering, the search for machines, mechanisms, machine tools and other equipment that works under variable loads is widely conducted. During work from the actions of variable loads in machine parts according to the result and changes in stress. Incorrectly defined margin of safety of parts with non-standard changes will lead to breakdowns and destruction, as well as machine accidents. Thus, a more precisely defined safety margin is required in parts in which the maximum stress cycles vary according to a step law. The purpose of the article is to study the processes of a non-standard mode of voltage change, which change according to a step law and receive the number of cycles after which the destruction of the part occurs. The task takes place in the investigated values of the equivalent stress, according to the parameters of which the coefficient of production of the safety margin under the action of non-standard stresses. When performing the calculations of the parts, ultimately, the margin of safety during simultaneous action is changed to the value of normal and tangential stresses, which have different characteristics of stress cycles. These calculations are valid in the case when the amplitude changes do not vary over time, that is, for the established or stationary mode. However, in a number of reports, one can encounter such a situation when changes in the amplitude of stress cycles over time do not remain constant, that is, the so-called non-stationary regimes. Therefore, in a more detailed study, there is a margin of safety for non-standard stress changes. As a result of theoretical studies, the number of cycles after which parts are destroyed under the action of a load, characteristic of non-stationary modes of operation, is calculated and the coefficients of the safety margin of durability are determined.

strength, stress, number of cycles, margin of safety, destruction of the part, load

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