Kazumasa Moriya

Tensile loading-reloading Test of CFRP Strand Cables and monitoring of load history

Incremental oading-reloading test on a CFRP stranded cable has been conducted under both twist free and twist fixed conditions. The effect on the tensile loading-reloading properties of CFRP cables twist confinement is investigated. The maximum tension capacity under twist free condition is 40% less than that under twist fixed condition. The electrical resistance of strand of CFRP cable along the fiber direction as well as the acoustic emission signals have been monitored during the test. The change of electrical resistance and the AE behavior are strongly correlated each other. It is suggested that the electrical resistance measurement could be effective for detecting of maximum load history of CFRP cable. Key Worth: CFRP, cable, twist fix or free condition, damage detection, electric monitoring

Resistance Spot Welding of CFRTP Composite Laminates.

Resistance spot welding concepts for fastening and attaching structural components made of CFRTP composite laminates are presented. Due to the presence of touching fibers, CFRTP laminates exhibit electrical conductivity in the direction transverse to fiber axes as well as in the fiber direction. Therefore, passing an electric current through two overlapping CFRTP laminates, which are sandwiched between upper and lower electrodes, Joule heat is generated in the region of current concentration to melt them together. When the current flow ceases, their contacting surfaces rapidly cool down and are joined together in one spot. One and three dimensional transient heat transfer analyses have been carried out to provide welding variables appropriate for the spot welding of CFRTP laminates. In the experiment, two pieces of CFRTP coupon specimen made of a commingled yarn prepreg are spot welded for various current and time combinations to investigate the effects of welding variables on the weld strength. Although the material properties of CFRTP composites which directly influence the weldability, —anisotropy, resistivity, thermal conductivity and melting temperature, etc. —are significantly different from those of metals, sound spot welds are produced by the present method.