Analytical and Experimental Study of Key Performance of Helicopter Rotor Torsion-Tension Straps

As a crucial component of rotor systems, tension and torsion (TT) straps, recognized for their compact structure, have been adopted in advanced helicopters such as the SB > 1, EC145, and Mi-26. This paper presents an analytical investigation and experimental study on the key performance of TT straps. A method for rapidly evaluating the performance of the torsional deformation segment was developed. The size parameters and material properties of the torsional deformation segment that greatly influence the torsional stiffness and the stress distributions of TT straps were comprehensively identified and clearly investigated. Moreover, an experimental study of four cases of TT straps was carried out to verify the influence of the torsional deformation segment length, material, and connector segment structure on TT strap performance. The experimental results confirm that the rapid evaluation method provides high accuracy in assessing the stiffness and stress performance of TT straps, with deviations in stiffness less than 10%. The correlation between the calculated stress and shear forces and the experimental failure modes of the connector segments validates the effectiveness of the method in capturing key parameters. This research provides a theoretical and practical basis for designing critical key parameters of TT straps, facilitating a dramatic reduction in performance assessment time from days to hours and enabling the immediate identification of enhancement strategies. This accelerates the design process, thereby contributing to enhanced design efficiency and reduced costs.