Experimental and Analytical Investigation of Transverse Bending Resistance in Steel Threaded Joints

Rod ends are critical structural components primarily designed to sustain axial loads in mechanical and aeronautical assemblies. However, operational conditions may involve transverse loading, which induces significant bending stresses concentrated in the threaded shank region. This research presents an experimental investigation aimed at characterizing the elastoplastic bending behavior of the threaded portion of rod ends subjected to such off-axis loads. Specimens manufactured from precipitation-hardened stainless steel 17-4 PH were tested under both displacement and force control strategies. Each specimen was subjected to incremental loading until failure to determine the elastic limit, yield point, ultimate bending strength and fracture mode. The experimental results enabled a preliminary assessment of the static resistance of the threaded region; furthermore, a comparison with analytical formulations and empirical estimation methods available in the literature revealed promising agreement. These findings highlight the importance of accounting for non-axial loading in the design of threaded joints for critical applications. This study establishes a baseline for broader experimental campaigns aimed at validating these results and exploring fatigue behavior under cyclic transverse loads.