Improving the Method of Assessing the Bearing Capacity of Complex Technical Systems

Abstract

The new method for assessing the bearing capacity of structural elements of complex technical systems, taking into account single and complex factors in a wide range of durations (N = 103…108 cycles) with different amounts and combinations of their actions is proposed. Based on the system analysis, the classification of negative and positive impact factors was performed and it was shown that the main one of them, that reduces the bearing capacity, is a combination of corrosion and fatigue processes. As positive factors that increase the cyclic strength and durability of structural elements, the technologies for surface strengthening of welds and the application of new corrosion-resistant polymer coatings on stressed sections of elements are proposed. To assess the influence of the acting factors, 5 series of model tests were performed on the corrosion fatigue of steel samples with various combinations and numbers of factors (open air, corrosive environment, stress concentration, weld coatings, strengthening), which made it possible to form mathematical models of the action of these factors in the form of functions of corrosion coefficients for strength and durability. Unlike the current calculation method, which assess the bearing capacity only at the inflection point of the branches of the corrosion fatigue lines ( $${\rm N} \approx$$ 7 ⋅ 106 cycles), the new method makes it possible to evaluate the strength and durability in the entire range of $${\rm N}$$ = 103…108 cycles and, by clarifying the calculation procedures, to ensure high productivity and reliable uptime of specified elements with minimal material consumption.