Influence of thermo-mechanical coupling effects on the stiffness characteristics of dynamic cables

During the service period of dynamic cables, in addition to withstanding mechanical loads such as tension and bending, thermal loads are generated due to the power transmission function, creating a thermo-mechanical coupling field that affects their mechanical properties including stiffness. Based on the periodic structural characteristics of dynamic cables, this paper introduces the asymptotic homogenization method to construct a finite element model with periodic boundary conditions, simplifying the computational domain to the helical period of the cable's internal components. This establishes an efficient method for analyzing the equivalent stiffness of the cable structure. By considering the effects of thermal expansion and softening, this study systematically explains and analyzes the influences of thermal loads on the dynamic stiffness of cables, revealing the correlation between these factors and cable stiffness. Furthermore, it explores the influence of effective tension, hydrostatic pressure, and thermal load on the nonlinear bending stiffness of the cable structure. The research shows that thermal loads cause expansion and softening effects, leading to a 32.54 % decrease in tensile stiffness, with expansion being the dominant factor, and a 21.51 % decrease in bending stiffness, with softening being the dominant factor while expansion has little effect. Changes in effective tension, hydrostatic pressure, and thermal load mainly affect the stick and slip zones in the nonlinear bending stiffness of dynamic cables. This provides critical data that are closer to actual working conditions for subsequent studies on dynamic cable configuration optimization and fatigue life assessment.