• Journal of the Korean Society of Industry Convergence
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• v.3 no.1
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• pp.61-67
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• 2000

Effective shear modulus of continuous fiber reinforced polymeric composites is measured using a modified Iosipescu Shear Test(IST) and compared with data obtained by finite element analyses that a concept of unit cell is. It is found that the numerical results of the longitudinal shear modulus give a good agreement with experimental data at lower fiber volume fraction. In this paper, both the distance and stress transfer between the fibers are discussed as the major factors.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2001.05a
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• pp.122-125
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• 2001

The objective of this research is to develop hybridized yarns for thermoplastic composites, and to examine tile effect of cooling rate on mechanical properties of the composites. The co-braided yarn utilizing carbon fibers as reinforcements and Nylon 66 fibers as matrix materials has been fabricated. Thermoplastic composites have been manufactured by the hot-press forming process. For the processing conditions, cooling rates of $-2.5^{\circ}C$/min and $-60^{\circ}C$/min have been considered. Three-point bending test and losipescu shear test were performed to investigate the effect of the cooling rate and the surface treatment of carbon fibers. SEM photographs were used to investigate the fracture surfaces of the tested samples. The cooling rate of $-60^{\circ}C$/min resulted in the higher strength and elastic modulus for bending and shear tests. The composites of the epoxy-sized carbon fibers showed the lowest strength due to the degradation of the sizing material during the thermoforming process.