Comparative analysis of the stress state of a bolted joint based on an analytical approach using SFEM and experimental results

The main types of connections are welded, riveted, and bolted. Bolted connections have many advantages over other types of connections, namely: high manufacturability, reliability, and speed of installation work, so we will further consider various approaches to modeling bolted connections. One of the most crucial and important points in the design of a structure is the calculation of the connection elements of the components, since the reliability of the structure as a whole depends on the accuracy and reliability of the calculation results. For a wide range of tasks, the finite element method (FEM) is often used in calculations; this numerical method has proven to be one of the most common and versatile. When calculating elements of assemblies such as bolts, rivets, etc., simplified design schemes are usually used, but this approach does not allow for a complete analysis of the distribution of forces. For a complete analysis, it is necessary to create detailed spatial models, which in turn leads to the need to solve systems of high-order equations. To increase the efficiency of the FEM, it is necessary to combine it with the method of distribution of unknowns, as a result, the resulting approach is called the semi-analytical finite element method (SFEM). The bolt, bolt head, and nut were modeled by spatial elements, and the bolt tension was modeled by a load from uniform heating. The obtained results of the stress-strain state using the finite element method and the semi-analytical finite element method allow us to conclude that there is a slight difference in the stress distribution in the spatial formulation of the FEM and SFEM with experimental data and allowed us to identify a rational approach to modeling bolt tension.