• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.10 s.113
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• pp.920-928
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• 2006

Fiber-reinforced composites transmitting microwaves of certain frequencies or bands were proposed. These frequency selective fabric composites(FSFCs) are fabricated by weaving carbon fibers and dielectric fibers that build periodic patterns. Design parameters affecting the electromagnetic characteristics of FSFCs were widely discussed, Then the electromagnetic characteristics of a fabricated plain-weave FSEC were investigated with regard to the electrical conductivities of carbon roving, the fiber undulation, and the aperture-to-cell ratio, for the electrical conductivities, its dependence on frequency as well as on the fiber volume fraction of carbon roving was taken into account. Constituent material properties and the fiber undulation had little effect on the EM properties of the fabricated FSFC, while the aperture-to-cell ratio made a profound effect on them.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.6
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• pp.717-723
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• 2010

Many researchers have studied woven fabric carbon-fiber-reinforced composite (CFRP) materials but the study of fatigue crack propagation in composites has been insufficient. It has known that the crack propagation behavior differs depending on the load and the fiber direction. In this study, the fatigue crack propagation along two different fiber array directions ($0^{\circ}$, $45^{\circ}$) in plain woven CFRP composite was investigated. Fatigue crack propagation tests were conducted on the woven CFRP composite under a sinusoidal waveform load with stress ratios of 0.1 at a frequency of 10 Hz. Once the results of the tests were obtained, fatigue crack propagation rates (da/dN) were plotted against the energy release rate amplitude (${\Delta}G$), and it was observed that either mode I crack propagation or mixed mode crack propagation occurs depending on the fiber array direction.

• Composites Research
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• v.18 no.2
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• pp.30-37
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• 2005

In this paper, geometrically non-linear finite element analyses were performed to study the mechanical behavior of the material system of the envelope of stratospheric airships. The microstructure of the load-bearing plain weave layer was identified and modeled. The Updated Lagrangian formulation was employed to consider the geometric non-linearity as well as the induced structural non-linearity for the fiber tows. The stress-strain behavior was predicted and the effective elastic modulus was calculated by numerical experiments. It was found the non-linear stress-strain curves were largely different from those by linear analysis. And non-linear elastic moduli were much higher than linear elastic moduli. The difference was more distinguishable when the tow waviness ratio was smaller.