CFRP Cables Research Articles

炭素繊維複合材ケーブルの回転拘束および回転自由引張試験と電気抵抗法によるモニタリング

A simple tension test for CFRP 1×7 stranded cables have been conducted under both rotation-free and rotation-fixed conditions. The relationship between the tensile properties of CFRP cables and the end conditions of the specimen were investigated. It was found out that tensile strength of CFRP cable decreased according to the increase of the angle of untwist in these tests. The relationship between the resistance change of the fiber direction and the elongation of unidirectional carbon fiber composites has already been reported. In this tensile test, the resistance of the strand (core and side wires) of CFRP cable along the fiber direction and AE signal were measured and the propagation of damage of the CFRP was monitored and examined by the non-destructive method. From the test results, the relationship between load and resistance change and AE behavior was investigated until the CFRP cable failed. Data for damage evaluation of CFRP cable by the non-destructive method under tensile loading was obtained.

Mechanical characterization of unidirectional CFRP thin strip and CFRP cables under quasi-static and dynamic tension

Under uniaxial tension, full stress-strain curves up to fracture and mechanical properties of a variety of CFRP cables having different structures are evaluated experimentally at three strain rates ranging from quasi-static (10-5 s-1) to dynamic (102 s-1). Such properties as tensile strength, chord or tangent modulus, strain at tensile strength and absorbed energy per unit volume are obtained. Experimental difficulties on stress and strain measurements and specimen fastening are overcome by introducing special instrumental arrangements and an expansive-cement fastening technique. For all cables, at quasi-static (10-5 s-1) and intermediate (10-2 s-1) strain rates, the stress-strain relation is linear. On the other hand, at a dynamic (102 s-1) strain rate, the stress-strain relation is non-linear and all cables tend to increase their elastic modulus and tensile strength. This obviously leads to increase of the absorbed energy per unit volume under dynamic tension. However, the strain at tensile strength remains almost the same at all strain rates. Thus, from a consideration based on the fracture strain criterion, it is concluded that strain rate insensitivity is assured for all cables.

炭素繊維強化複合材ケーブルの直接通電による成形と引張特性に関する研究

For the construction of large space structures, onorbit fabrication of cable net structures is proposed. This is accomplished by transporting coiled stock of prepreg of CFRP cable to the orbit from the earth and curing it by means of resistance heating whose operating power is supplied by solar electric system. Laboratory tests indicate that CFRP cables can be cured uniformly and precisely with the specified cure cycle by passing low voltage current through them. Tensile tests of CFRP cables cured by resistance heating as well as those of uncured ones have also been performed and the results show that cured cables exhibit tensile strength and stiffness which are about two times higher than those of uncured ones. In preparing for tensile specimens of uncured cables, it has been found that any part of CFRP cables can be left uncured by the present method without changing curing process. At these uncured portions, they can be bent for folding and be tied to other structural members with knots without using mechanical hinges or joints.