• Journal of the Korean Ceramic Society
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• v.50 no.6
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• pp.359-363
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• 2013

Silicon carbide and its composites are being considered as a nuclear fuel cladding material for LWR nuclear reactors because they have a low neutron absorption cross section, low hydrogen production under accident conditions, and high strength at high temperatures. The SiC composite cladding tube considered in this study consists of three layers, monolith CVD SiC - $SiC_f$/SiC composite -monolith CVD SiC. The volume fraction of SiC fiber and surface roughness of the composite layer affect mechanical and corrosion properties of the cladding tube. In this study, various types of SiC fiber preforms with tubular shapes were fabricated by a filament winding method using two types of Tyranno SA3 grade SiC fibers with 800 filaments/yarn and 1600 filaments/yarn. After chemical vapor infiltration of the SiC matrix, the surface roughness and fiber volume fraction were measured. As filament counts were changed from 800 to 1600, the surface roughness increased but the fiber volume fraction decreased. The $SiC_f$/SiC composite with a bamboo-like winding pattern has a smaller surface roughness and a higher fiber volume fraction than that with a zigzag winding pattern.

• Composites Research
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• v.31 no.4
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• pp.161-170
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• 2018

Cylindrical composite lattice structures are manufactured by filament winding process. The fiber volume fraction non-uniformity and resin rich layers that can occur in the manufacturing process affect the stiffness and strength of the structure. Through the cross-section examination of the hoop and helical ribs, which are major elements of the composite lattice structure, we observed the fiber volume fraction non-uniformity and resin rich layers. Based on the results of the cross-section examination, the stiffness of the ribs was analyzed through the experimental and theoretical approaches. The results show that the fiber volume fraction non-uniformity and resin rich layers have an obvious influence on the rib stiffness of composite lattice structure.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2001.10a
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• pp.144-148
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• 2001

A proper estimation of the mechanical properties for composites has been required for better design/selection of constituents for composite materials. Present investigation shows the simulation results for ceramic reinforced metal matrix composite under uniaxial transverse tensile loading. The resulting transverse mean stress with the transverse mean strain was described for composites as a function of the volume fraction with two different types of interfacial bonding: (1)strongly bonded interface, and (2)no bonded interface. A two-dimensional finite element modeling and analysis were conducted based on the unit-cell concept with an assumption of a regular square arrangement of the reinforcement within the composite. The mean stress was generally increased with the ceramic volume fraction for composite with strong interface bonding. The micromechanics concept combined with finite element modeling for composite can be used in order to predict the transverse properties of composites with a priori known properties of constituents.

• Composites Research
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• v.26 no.4
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• pp.218-222
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• 2013

This study demonstrated that a slag, an industrial solid waste, can be used as a structural reinforcement. The mechanical properties(tensile strength and Elastic modulus) of slag reinforced composite(SRC) was investigated as functions of slag particle size (8~12 ${\mu}m$ and 12~16 ${\mu}m$) and volume fraction (0-40 vol.%). In order to investigate the interface and a degree of particle dispersion which have an effect on mechanical properties, optical microscopic images were taken. The results of tensile tests showed that the tensile strength decreased with an increase in slag volume fraction and particle size. The elastic modulus increased with an increase in slag volume fraction and particle size except for 30 vol.% SRC. The tensile strength decreased with an increase in slag particle size. The microscopic picture showed SRC has fine degree of particle dispersion at low slag volume fraction. SRC has a good interface at every volume fraction. However particle cluster was incorporated with an increase in slag volume fraction.

• Steel and Composite Structures
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• v.12 no.2
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• pp.117-127
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• 2012

This paper deals with an experimental investigation to study the effect of fibre content on the stability of composite plates with various aspect ratios. Epoxy based glass fibre reinforced composite plates with aspect ratio varying from 0.4 to 1 and with volume fractions of 0.36, 0.4, 0.46, 0.49 and 0.55 are used for the investigation. From the study it is observed that for plate with aspect ratio of 0.5 and 0.4 there is no buckling and the plate got crushed at the middle. As the volume fraction increases the buckling load also increases to a limit and then began to reduce with further increase in fibre content. The optimum range of fibre content for maximum stability is found between 0.49 and 0.55. Polynomial expressions are developed for the study of buckling behaviour of composite plates with different volume fractions in terms of load and aspect ratio.

• Journal of Life Science
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• v.10 no.4
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• pp.374-379
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• 2000

This study was attempted to evaluate an agonistic activity to benzodiazepine receptor of several medicinal pants, which have been used as sedatives in oriental medicine. The activities of the methanol extracts of composite preparation of oriental drugs were compared with those of the simple drugs, furthermore, the active fraction was found out from the simple preparation. Inhibitory effects of composite preparations, Cyperus rotundus/Acorus gramineus, Thuja orientalis/Euphoria longan, Thuja orientalis/Albizzia julibrissin, on the binding of ${[^3H]}$Ro15-1788, a selective benszodiazepine receptor antagonist to benzodiazepine receptor of rat cortices, were observed to be lower than those of corresponding simple preparations. These unexpected results suggest that some components of the composite druge may rather act as an obstacle, not to show the sinergistic effect. The methanol extracts of Cyperus rotundus having the highest activity were fractionated using polar and nonpolar solvents to give ethylacetate and hexane fractions, respectively. The ethylacetate fraction containing relatively polar components exhibited much higher activity than the hexane fraction, which consiste of nonpolar agonist, binding to benzodiazepine receptor. However, in the presence of GABA, this fraction inhibited ${[^3H]}$flunitrazepan binding, and these positive GABA shift supported the strong possibility of agonistic activity to benzodiazepine receptro. As a result, it may be concluded that the substance or substances with neurochemical properties as a benzodiazepine receptor agonist may contribute to the sedative property of Cyperus rotundus.

• Korean Journal of Metals and Materials
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• v.47 no.9
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• pp.550-557
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• 2009

In this study, bronze or SUS304 powders blended with 10 wt.% diamond particles were used to prepare metal/diamond composite materials deposited by cold spraying. The effects of matrix metal, diamond partical size, and the thickness of the Ni coating on the diamond were studied on Al 6061 substrate. The results showed that the hardness of the metal/diamond composite coating layers was higher than that of the same composite materials when using the sintering method. The fraction of diamond content in the coated layer increased when the metal matrix was soft. When the size of the diamond particles was reduced, the fraction of the diamond particles increased. In addition, in the case of diamond with a thicker Ni-coated layer, the fracturing of diamonds was mitigated in the composite coating layers.

• Proceedings of the Korean Society For Composite Materials Conference
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• 1999.11a
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• pp.164-167
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• 1999

This study concerns with the effect of fiber weight fraction on the fracture toughness of long glass-fiber reinforced polypropylene composites. Fracture tests were conducted using compact tension (CT) specimens made of glass fiber polypropylene composites. Three fiber weight fractions of 20%, 30%, and 40% were used. Fracture toughness was determined from the compliance method. Results showed that compliance decreased with increasing fiber weight fraction while critical load increased with fiber weight fraction. Averaged fracture toughness increased 14% as fiber weight fraction increased from 20% to 40%.

• Journal of the Korean Society of Safety
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• v.24 no.2
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• pp.23-29
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• 2009

The hybrid composite materials are recently used in many field as an advanced material due to their high resistance to fracture. However, hybrid composite materials have several problems, especially delamination, compared with homogeneous materials such as an aluminum alloy, etc. In this study, we carried out the tensile test to study the tension failure appearances and tensile ultimate strength of CFRP/Al/CFRP hybrid composite materials. The CFRP material used in the experiment is a commercial material known as CU175NS in unidirectional carbon prepreg. Also Al/CFRP/Al hybrid composites with three kind length of a single edge crack were investigated for the relationship between an aluminium volume fraction and a crack length. The crack length was measured by a traveling microscope under a universal dynamic tester. Futhermore the stress intensity factor behavior was examined according to a volume fraction and an initial crack length ratio to a width.

• Computers and Concrete
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• v.25 no.4
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• pp.303-310
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• 2020

In this research, a hybrid mathematical model is derived using the higher-order polynomial kinematic model in association with soft computing technique for the prediction of best fiber volume fractions and the minimal mass of the layered composite structure. The optimal values are predicted further by taking the frequency parameter as the constraint and the projected values utilized for the computation of the eigenvalue and deflections. The optimal mass of the total layered composite and the corresponding optimal volume fractions are evaluated using the particle swarm optimization by constraining the arbitrary frequency value as mass/volume minimization functions. The degree of accuracy of the optimal model has been proven through the comparison study with published well-known research data. Further, the predicted values of volume fractions are incurred for the evaluation of the eigenvalue and the deflection data of the composite structure. To obtain the structural responses i.e. vibrational frequency and the central deflections the proposed higher-order polynomial FE model adopted. Finally, a series of numerical experimentations are carried out using the optimal fibre volume fraction for the prediction of the optimal frequencies and deflections including associated structural parameter.