METHODS FOR ENSURING THE RELIABILITY AND ECONOMIC EFFICIENCY OF AUTOMOTIVE ENGINES OPERATING IN HOT CLIMATIC CONDITIONS

Аннотация

This study explores methods for ensuring the reliable operation of automotive engines under hot climatic conditions. It emphasizes the importance of balancing reliability with economic factors, particularly through analyzing the relationship between component/system reliability and associated costs. The paper highlights the collaborative role of designers and reliability engineers, noting that traditional design methods alone are insufficient for modern engine development. Key topics include the use of safety factors, the limitations of empirical design approaches, and the need for optimized solutions incorporating new materials and technologies. The research also discusses statistical approaches to stress-strength analysis and the practical challenges posedbycost, time, and rapid technological change. Keywords (one line):engine reliability, hot climate, safety factor, mechanical components, design optimization,operational analysis, reliability theory, cost analysis, To ensure a given probability of failure-free operation, one of the main factors is to take into account the condition of minimum costs, for which it is necessary to determine the relationship between reliability and costs for each element and engine system. In practice, it is not always possible to use this condition due to the lack of data on the costs required to ensure a given level ofreliability[1]. The creation of reliable elements, systems and engines themselves is possible only if the efforts of designers and operational reliability specialists are combined. At the same time, the main role is assigned to the designer, and the reliability specialist supplements his knowledge by analyzing the reliability of the engine design and statistical analysis of operational data. At the present stage, the principle of ensuring the reliability of engines, based on the simple application of rational design methods, is insufficient to give a given reliability to an engine as a complex system. In this regard, it becomes necessary to single out an independent section in the theory of reliability, which would study the issues of reliability of elements and systems of engines. The followingfactors may serveas thebasis for this[2-5]: 1) insufficient design experience. The pace of technology change is so fast that it is almost impossibleforengine designers tocomplete thedesign; 2)cost and timeconstraints. Cost and timeare important, so thedesigner is not ableto learn from past mistakes, i.e. trial and error is not acceptable here; 3) the need to optimize resources. The creation of a working engine design must be optimized under constraints on such parameters as cost, reliability, weight, efficiency, performance and dimensions. Result and discussion. The nature of the change in the distribution of stresses and strength is shown in Fig.3. For convenience, it is assumed that the stress distribution is constant, while the strength distribution changes with time. If the distributions of stresses and strength are known, then according to the results of the relationship between them, it is possible to determine the reliabilityofthe work [6]. 183 Volume 4, issue 8, 2025 When designing the mechanical elements of the engine, a certain margin of safety is chosen, set by arbitrary strength factors. Such an approach to the choice of coefficients in a number of cases makes it possible to obtain a satisfactory design of engine parts, especially if their values are chosen on the basis of experience. But in modern conditions, when creating new engine designs, newapproaches, new materials and more consistent methods are required. In thiscase,it is important toconsider thefollowing indicators[8]: 1. Safety factor. In practice, there are several ways to calculate the safety factor S . This factor f can be defined as the ratio of the average strength μ to the average stress μ '. In this case, μ is s s s aparameterthat determines theappearance ofa failure, and μ ' -causing failure. s μs If thestress and strength are d S ifs = tri μ b' s u te 1 d . according tothe normal law, theuse of thecoefficient S f is very convenient. The method of choosing the safety factor is shown in fig. 4 It shouldbe noted that if the stress and strength have a large range of variability, the coefficient S loses its f meaning. Figure 1.Distribution ofstresses (b)and strength (v) depending onthetime(t )of work: a - at time t ; b - at time t ; 1 - stress distribution; 2 - strength; 3 - constant distribution of 1 2 stresses; 4—strength distributionover timeinterval (t —t ) 2 1 2.Margin ofsafety. It is determined bythe formulaSm \u003dS -1. f Coefficient Sm as S is a random variable, it reflects the idea of the need to separate the average f values ofstress and strength. In cases where reliability is assessed according to the established distributions of stress and strength parameters, traditional methods such as the Lagrange multiplier method, integer, linear 184 Volume 4, issue 8, 2025 and dynamic progra