Development and Validation of Analytical Model for Stiffness Analysis of Curvic Coupling in Tightening

Abstract

Curvic couplings are extensively used in aerospace machinery, such as helicopters, aeroengines, or other aircraft. In this paper, the behavior of bolted joints with curvic couplings is investigated to determine a method to describe the relationship between the stiffness parameters and the geometry of the parts of curvic coupling and external loads. The validity of the method is proven through experiments and finite-element simulation. Additionally, the study investigates the effects of the curvic height, curvic width, curvic thickness, pressure angle of curvic surface, and friction coefficient of curvic surfaces on the stiffness of disc parts. The analytical results show that the compression stiffness of both the curvic and ring parts of the disc has a relationship with the curvic rotation. Although the curvic compression stiffness tends to be constant in the bolt-tightening process for different curvic geometrical dimensions, the compression stiffness of the other disc parts has obvious differences owing to the various curvic geometrical parameters. By choosing appropriate pressure angles of the curvic surface or number, the stiffness of the curvic coupling can be kept stable in the bolt tightening course. The stiffness parameters of curvic couplings can be determined by the analytical model, regardless of how the geometry of the parts of curvic couplings or the external loads are changed.