Machines. Technologies. Materials.
Vol. 20 (2026), Issue 6, pg(s) 210-213

MACHINES

Rapid prototyping of a friction coupling for joining rebar

  • 1 Faculty of Mechanical Engineering, University of Montenegro, Podgorica, Montenegro

Abstract

Friction couplings for joining rebar are widely used in civil engineering and mechanical structures, including the construction of high-rise buildings, towers, bridges, overpasses, tunnels, dams, and other infrastructure. These friction couplings are mechanical elements that provide a strong and reliable connection between the components being joined by transferring loads through the friction force generated between the contact surfaces. This force is applied by the geometry of the friction coupling and the installation-induced clamping force. The primary factor governing the proper selection and application of a friction coupling is the cross-sectional diameter of the rebar, as the friction coupling must be designed to withstand the loads encountered under service conditions. In addition, environmental influences, particularly the difference in the coefficients of thermal expansion of the joined materials, represent an important consideration. Another critical factor is the installation process itself, as the performance of the friction coupling depends directly on proper installation. Therefore, comprehensive testing of the installed friction coupling is essential to ensure its reliable performance throughout its service life. This paper presents an original design solution for the development of a friction coupling for joining Ø25 mm rebar, developed through three successive design iterations. The proposed friction coupling is intended to ensure structural integrity under static and dynamic loading, including seismic loading and vibration. An initial prototype design was developed in accordance with the applicable technical standards and validated using the Finite Element Method (FEM) to evaluate its load-bearing capacity under static loading conditions and identify potential stress concentrations. The prototype models were manufactured using the Fused Filament Fabrication (FFF) additive manufacturing process with the support of CAD/CAE systems. The friction coupling was ergonomically designed through mass and shape optimization.

Keywords

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