Solution validity analysis of calculation problems of parts for fatigue strength at repeatable variables stresses by the finite element method

Abstract

During the operation of the rolling stock of railways its parts are exposed to both constant and variable loads in time, magnitude and sign, which applies chiefly to its mechanical part. As a result, inside the parts under conditions of a variable stress-strain state, fatigue defects appear. Thus, along with the usual calculations of variable stress-strain state and the strength of the parts of the operation of the rolling stock of railways, in order to study the parameters of their reliability and durability, it is necessary to solve fatigue strength problems. At present full-scale field tests, followed by a stage of fine-tuning of the product to obtain the necessary parameters of its reliability and durability remain the main approach. This approach is effective because it is characterized by obtaining objective data in the form of a graphical dependence of fatigue characteristics and numerical values of the endurance limit. However, it also has significant disadvantages associated with time and material costs, the most significant one being the low level of informativeness regarding the accuracy of determining stress fields in the parts of the product. To solve this problem, the paper considers the study of the possibility of usage and reliability of computational and theoretical approaches to the analysis of fatigue characteristics of parts using the finite element method, as the most effective from the viewpoint of mathematical modeling of parts geometry, mechanical characteristics of the material and the effective loading. The problem of analyzing the reliability of the numerical solution of the finite element method in the form of a stress-strain state of the part is solved in relation to the well-known analytical (semi-empirical) solution presented in literature. By means of finite element modeling, the result of the fatigue calculation was obtained in graphical and numerical form, with further comparison of the obtained data with an analytical solution, which will allow to evaluate the validity of the finite element method in problems of fatigue strength of products.