• 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.

• Journal of the Korean Institute of Gas
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• v.13 no.6
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• pp.29-33
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• 2009

In this study, the strength safety of a composite fuel tank which is fabricated by an aluminum liner of Al6061-T6 materials and composite layers of carbon/epoxy-glass/epoxy composites has been analyzed by using a finite element analysis technique. In order to enhance the durability of the composite fuel tank, an autofrettage process was used and compressed natural gas was supplied to the prestressed fuel tank. The FEM computed results on the stress safety of autofrettaged gas tanks were compared with a criterion of design safety of US DOT-CFFC and Korean Standard. The FEM computed results indicated that the stress safety of autofrettaged fuels tanks shows instability at the dome zone and uniform stability at the parallel body, which provide an evaluation data for a strength safety of autofrettaged composite fuel tanks. The computed results show that the stress safety of 9.2 liter composite fuel tanks satisfied the safety criteria of four evaluation items, which are provided by US DOT-CFFC and KS and indicated a safe design.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2005.11a
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• pp.169-172
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• 2005

A flywheel system is an electromechanical energy storage device that stores energy by rotating a rotor. The rotating part, supported by magnetic bearings, consists of the metallic shaft, composite rims of fiber-reinforced materials, and a hub that connects the rotor to the shaft. The delamination in the fiber wound composite rotor often lowered the performance of the flywheel energy storage system. In this work, an advanced hybrid composite rotor with a split hub was designed to both overcome the delamination problem in composite rim and prevent separation between composite rim and metallic shaft within all range of rotational speed. It was analyzed using a three-dimensional finite clement method. In order to demonstrate the predominant perfom1ance of the hybrid composite rotor with a split hub, a high spin test was performed up to 40,000 rpm. Four radial strains and another four circumferential strains were measured using a wireless telemetry system. These measured strains were in excellent agreement with the FE analysis. Most importantly, the radial strains were reduced using the hybrid composite rotor with a split hub, and all of them were compressive. As a conclusion, a compressive pressure on the inner surface of the proposed flywheel rotor was achieved, and it can lower the radial stresses within the composite rotor, enhancing the performance of the flywheel rotor.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.933-935
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• 2017

This paper deals with the influence of fungi for the thermal protective cork-based exterior insulator which protect a missile system from aerodynamic loads and heating during flight of missile. We consider the adhesion of cork-based composite on the composite motor case which fabricated by filament winding process. We also consider the importance of the requirement analysis for effective, successful system development under given system conditions. In order to develop the basic requirement analysis for the thermal protective cork-based exterior insulator, an experimental requirement analysis was accomplished, and some experimental comparing results, the study for preventing fungi are presented.

• Journal of the Korean Society of Propulsion Engineers
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• v.16 no.4
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• pp.9-15
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• 2012

In this paper, the bearing strengths and fracture behaviors of the pin-jointed carbon fiber/epoxy composites were investigated through pin loading test with acoustic emission technique. The composites were fabricated by a filament winding process, and three types of laminated patterns were considered. Type 1 was fabricated with stitch, Type 2 was fabricated without stitich and Type 3 was fabricated with prepregs. According to the results, bearing strength of Type 1 was 3.3% lower than that of Type 2 and that of Type 3 was highest. Type 1 and Type 2 revealed a net-tension failure mode, respectively, whereas Type 3 pattern exhibited a bearing failure mode. Also, acoustic emission energy of the Type 3 was higher than that of the Type 1 and Type 2. Therefore, the Type 3 was found to be structurally safer than the Type 1 and Type 2.

• Composites Research
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• v.36 no.2
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• pp.80-85
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• 2023

A cylindrical composite lattice structure is manufactured by filament winding. The distribution of nonuniform fiber volume fraction induced by the manufacturing process can be observed. The stiffness and buckling characteristics can be influenced by non-uniform fiber volume fraction. In this paper, the effect of non-uniform fiber volume fraction through thickness direction on the torsional buckling load of the cylindrical composite lattice structure was examined. The stiffness variation induced by the non-uniform fiber volume fraction was applied to the finite element model, and buckling analysis was performed. The variations of buckling load with variations of fiber volume fraction were compared. The non-uniform fiber volume fraction reduced the torsional buckling load of the composite lattice structure.

• Composites Research
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• v.29 no.1
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• pp.40-44
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• 2016

Nuclear fuel cladding used in a nuclear power plant must possess superior oxidation resistance in the coolant atmosphere of high temperature/high pressure. However, as was the case for the critical LOCA (loss-of-coolant accident) accident that took place in the Fukushima disaster, there is a risk of hydrogen explosion when the nuclear fuel cladding and steam reacts dramatically to cause a rapid high-temperature oxidation accompanied by generation of a huge amount of hydrogen. Hence, an active search is ongoing for an alternative material to be used for manufacturing of nuclear fuel cladding. Studies are currently aimed at improving the safety of this cladding. In particular, ceramic-based nuclear fuel cladding, such as SiC, is receiving much attention due to the excellent radiation resistance, high strength, chemical durability against oxidation and corrosion, and excellent thermal conduction of ceramics. In the present study, cladding with $SiC_f/SiC$ protective films was fabricated using a process that forms a matrix phase by polymer impregnation of polycarbosilane (PCS) after filament-winding the SiC fiber onto an existing Zry-4 cladding tube. It is analyzed the oxidation and microstructure of the metal cladding with $SiC_f/SiC$ composite protective films using a drop tube furnace for thermal shock test.