Stress analysis and frictional behavior of helical power core components in marine dynamic cables under axial tension and bending loads

As the development of offshore wind energy continues increasing, the utilization of dynamic cables becomes crucial. Helical power core components are essential functional elements in marine dynamic cables, and understanding the mechanical behavior of these spiral structures under complex external loads has garnered significant attention. This study introduces a comprehensive stress analysis model for helical power core components in dynamic cables subjected to axial tension and bending loads. Unlike previous simplified models, the proposed approach fully accounts for the double-helix structure in the conductor configuration. By introducing Darboux vectors, which encompass two curvatures and one twist, the mechanical response models for both single-helix and double-helix conductor wires under combined tension and bending loads are developed. The study further delves into the interactions between local frictional contact and the geometric characteristics of the helical structure, leading to the formulation of analytical models for contact stresses in helical components. Additionally, a multi-layer pressure transmission model for the helical power core is proposed based on the force action-reaction principle. To account for frictional forces, Coulomb’s friction law is integrated into the model, and an iterative solution procedure is provided to obtain friction-slip results. The theoretical model is verified using finite element (FE) simulations and existing experimental data, specifically applied to a high-voltage direct current (HVDC) cable. The results demonstrate the accuracy of the model in predicting cross-sectional stresses under nonlinear combined tension and bending moments. This work offers valuable technical support for the analysis and design of marine dynamic cables under complex loading conditions, contributing to the optimization of their mechanical performance.