Analysis of the Stress–Strain State of a Flanged Connection Based on an Analytical Approach Using the Finite Element Method and Comparison with Experimental Data

Abstract

This study presents a comprehensive analysis of the stress–strain state of a flanged bolted pipe connection under bending moment using the finite element method (FEM) in a spatial formulation. The investigation was conducted using three-dimensional eight-node isoparametric and quadrilateral shell finite elements in specialized software packages, as well as using the component-based finite element method. This approach allows detailed reproduction of the spatial behavior of the structure and enables the evaluation of local stresses and deformations occurring in critical areas of the connection.

Particular attention was given to the connection nodes, especially bolted joints, which determine the overall stiffness and load-bearing capacity of the system. The modeling accounted for bolt pre-tension, compression and tension zones in the flanged connection, as well as the potential eccentricity of the applied load, which can arise from both initial and acquired defects in the structure. Such a comprehensive approach enables prediction of the connection behavior under operational loads and assessment of the overall structural reliability.

The numerical modeling results were compared with experimental data and calculations performed using different software packages. The comparison showed high consistency in stress distribution and local deformations when using three-dimensional eight-node isoparametric elements, whereas the use of quadrilateral shell elements and the component-based finite element method exhibited greater deviations from experimental observations. The analysis demonstrated that the accuracy of predicting the stress–strain state largely depends on the chosen element geometry and the adequacy of modeling contact interactions between elements.

The results confirm the effectiveness of three-dimensional eight-node isoparametric finite elements for accurately predicting the stress–strain state of flanged bolted connections. The study also emphasizes the importance of considering the pipe-to-flange attachment zones during design and operation, as well as the potential of FEM-based methods for optimizing structural parameters and improving overall reliability.