らせん状ストランドにおける引張剛性最大化

抄録

Helical strands are widely used in products such as electrical wire, wire harnesses, wire ropes and the like. Effective stiffness can serve as one of the evaluation indexes in the mechanical design of the strand. Specifically, the mechanical design guideline of a wire harness requires both high tensile stiffness and low bending stiffness. A typical basic structure of a wire harness is composed of a bundle of a multiple of metal wires helically twisted together. A large number of wire harnesses can be manufactured according to the material, diameter, combination of a helical angle at the time of twisting and direction thereof. However, it is necessary to estimate what type of microscopic structure maximizes the mechanical performance since the load-displacement response depends on the combination of the material and geometric factors. In this study, we derive the effective stiffnesses for (1+n)- and (3+n)-strands based on a rod theory. Then we develop the optimization program to determine the microscopic parameters to maximize the tensile stiffness of the strands. We found that the tensile stiffness of (1+n)-strand is higher than that of (3+n)-strand.