FEM analysis of stress-strain state and material consumption of RHS with longitudinal gap and weld during the tests

Abstract

The paper implements a method for analyzing the stress-strain state of rectangular hollow sections (RHS) by finite-element modeling (FEM) of tests for three-point bending and torsion. Design schemes, 3-D solid-state and deformable models have been developed using the automated analysis and CAD/CAE system software, made it possible to obtain equivalent stress distributions and displacements in models. A simulation of tests for RHS with a cross section of 40 mm × 50 mm, manufactured in two ways, was carried out: (a) by direct-forming of galvanized steel strips on roll-forming mill in a semi-closed section with a longitudinal gap of 0.5 mm between the edges formed on a 40 mm web (DF-RHS); (b) similar direct-forming to the closed section and next welding the edges to a longitudinal weld along the web middle of 50 mm (DFW-RHS). RHS with various wall thicknesses (t = 1.93 mm, 1.84 mm and 0.7 mm) was investigated, given the design features that depend on the manufacturing processes of structural sections. It was found DFW-RHS is stiffer by at least 50% compared to DF-RHS, which allows to savings the metal by reducing the RHS wall thickness by 62% while maintaining the same stiffness and ensuring high strength of structural section.