Aerospace Technic and Technology

The object of study in the article is the individual parts of aircraft units, applied to loads that change over time. The subject of study is models that describe fatigue resistance under asymmetric loads. The goal is to develop a fairly simple engineering technique for detecting parts of aircraft units operating under an asymmetric loading cycle. Tasks: general analysis of many approaches to design cycles before the destruction of parts of aircraft units, production with an asymmetric loading cycle; select calculations acceptable for practical calculations, determine the endurance limit under a symmetrical loading cycle for steels and aluminum alloys used in aircraft units; select a calculation to calculate the maximum amount of asymmetric cycle. Methods used engineering analysis of methods for constructing a fatigue curve for an asymmetric speed change cycle; calculation of the endurance limit for a symmetrical cycle of change depending on the properties of materials based on the results of experimental selection and calculation of the endurance limit of materials to calculate the endurance limits of materials; the finite element method for counting and increasing dimensions in parts in the Simulation software package in Solidworks packages. The obtained results are obtained: an equation is chosen for the structure of the curve with an asymmetric cycle of stress change, given mechanical properties of the material; selections are selected for calculation with acceptable accuracy according to the specified properties of the endurance limits of materials with a symmetrical loading cycle of steels and aluminum alloys used in aircraft units; calculations were selected to calculate the limiting value of the asymmetric oscillation of the cycle; a method for determining the constants of the Weibull distribution for the fatigue curve under an asymmetric load cycle is proposed. Conclusion: an engineering technique has been developed for determining the resistance of parts of aircraft units operating under loads that change over time according to an asymmetric cycle.

fatigue strength; fatigue resistance; asymmetric cycle; fatigue curve; endurance; Weibull distribution

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