Parameters for Modeling Stranded Cables as Structural Beams

This paper presents a method for determining the effective homogenous beam parameters for stranded cables made up of non-homogenous wires, as well as characterization of the attachment method commonly used for cable harnesses on space structures. There is not yet a predictive model for quantifying the structural impact of cable harnesses on space flight structures, and towards this goal, the authors aim to predict cable resonance behavior from basic cable measurements. Cables can be modeled as shear beams, but the shear beam model assumes a homogenous, isotropic material, which a stranded cable is not. Thus, the cable-beam model requires both knowledge of the cable constraints and calculation of effectively homogenous properties, including density, area, bending stiffness, and modulus of rigidity to predict the natural frequencies of the cable. Through a combination of measurement and correction factors, upper and lower bounds for effective cable properties and attachment stiffness are calculated and shown to be effective in a cable-beam model for natural frequency prediction. Although the cables investigated are spaceflight cables, the method can be applied to any stranded cable for which the constituent material properties can be determined.