• Steel and Composite Structures
• /
• v.27 no.4
• /
• pp.525-536
• /
• 2018

This paper focuses on the application of the first-order shear deformation theory (FSDT) to thermo-elastic static problems of functionally graded carbon nanotubes reinforced composite (FG-CNTRC) cylindrical pressure vessels. A symmetric displacement field is considered as unknown function along the longitudinal direction, whereas a linear distribution is assumed along the thickness direction. The cylindrical pressure vessels are subjected to an inner and outer pressure under a temperature increase. Different patterns of reinforcement are applied as distribution of CNTs. The effective material properties of FG-CNTRC cylindrical pressure vessels are measured based on the rule of mixture, whereas the governing equations of the problem are here derived through the principle of virtual works. A large parametric investigation studies the effect of some significant parameters, such as the pattern and volume fraction of CNTs, on the longitudinal distribution of deformation, strain and stress components, as useful tool for practical engineering applications.

• Journal of Advanced Marine Engineering and Technology
• /
• v.22 no.2
• /
• pp.139-145
• /
• 1998

Filament winding method is widely used for composite fabrications using low viscosity liquid for-mation and processing asymmetrical structures of pressure vessel pipe rocket motor case etc. The filament winding method is affected by several parameters such as pot life of process time viscosi-ty of resin filament winding temperature and schedules curing condition and post curing condi-tion of resin. To develope high functional composite materials the rotation(5, 15, 20, 30rpm) of the winding machine was controlled by D.C motor. And the wiper to give proper tension was equipped between strand and resin bath. The resin is hooked by the design wiper. The adequate cure schedule was found by DSC. NOL ring test is carried out to investigate the basic physical properties such as design technology. The void contents in filament winding is generally higher than that of the prepreg laminated plate. These high contents of void can make a crack in resin in spite of low deformation. These problem was solved by giving tension in processing. To improve the characteristics of fiber volume fraction void contents resin/fiber bonding the winding speedc is changed under constant tension. It was found that resin impregnation was not different from in fiber contents void contents at the range of 0.5~1kg tension but it was found that resin was not impregnated at the above of 1.5kg tension. In burst test a pure PE liner was failed at a nozzle part under the $14kg/\textrm{cm}^2$ pressure but a pressure vessel of CNG was failed at a cylinder part under the $200kg/\textrm{cm}^2$ pressure.

• Proceedings of the KSME Conference
• /
• 2007.05a
• /
• pp.23-27
• /
• 2007

To store hydrogen with high pressure is one of key technologies in developing FCVs (fuel cell vehicles). Especially, metal lined composite structure, which is called Type 3, is expected to effectively stand highly pressurized hydrogen since it has high specific strength and stiffness as well as excellent storage ability. However, it has many difficulties to design Type 3 vessels because of their complex geometry, fabrication process variables, etc. In this study, therefore, optimal design of Type 3 vessels was performed in consideration of such actual circumstances using genetic algorithm. Additionally, detailed finite element analysis was followed for the optimal result.

• Structural Engineering and Mechanics
• /
• v.43 no.6
• /
• pp.771-794
• /
• 2012

This paper presents a multi-objective evolutionary algorithm for combinatorial optimisation and applied for design optimisation of fiber reinforced composite structures. The proposed algorithm closely follows the implementation of Pareto Archive Evolutionary strategy (PAES) proposed in the literature. The modifications suggested include a customized neighbourhood search algorithm in place of mutation operator to improve intensification mechanism and a cross over operator to improve diversification mechanism. Further, an external archive is maintained to collect the historical Pareto optimal solutions. The design constraints are handled in this paper by treating them as additional objectives. Numerical studies have been carried out by solving a hybrid fiber reinforced laminate composite cylindrical shell, stiffened composite cylindrical shell and pressure vessel with varied number of design objectives. The studies presented in this paper clearly indicate that well spread Pareto optimal solutions can be obtained employing the proposed algorithm.

• Proceedings of the Korean Society For Composite Materials Conference
• /
• 2003.04a
• /
• pp.31-36
• /
• 2003

Recently, composite materials are widely used for nozzle, pressure vessel, skins of satellite and many structures under condition of high temperature due to good thermal characteristics such as low CTE, heat-resistance, etc. Fiber optic sensors, especially FBG(fiber Bragg grating) sensors, can be a good counterproposal of strain gages for the measurement of material properties of composites under high temperature. In this research, T700/Epoxy specimens with embedded FBG sensors were fabricated and tested at the Instron with thermal chamber from room temperature to $400^{\circ}C$. The effects of embedding optical fiber on material properties were also verified. And, the experimental results were discussed and analyzed by microphotographs of the composite specimen.

• Archives of Reconstructive Microsurgery
• /
• v.1 no.1
• /
• pp.51-55
• /
• 1992

Problems of composite tissue transfer commonly arise when a single indispensable recipient vessel receives the graft vssel, and the graft vessel must be sutured in end-to-side fashion so as not todisturb the vascularity of the recipient vessel. The triangular flap in the recipient vessel wall gives an intact endothelial surface when the flow of blood stream is presented and may reduce the chance of anastomosis. We selected mature Wistar rats weighing over 450 grams to compare the conventional longitudinal slit from the triangular flap in the recipient carotid artery over bloood pressure and blood flow when the donor carotid artery was anastomosed in end-to-side fashion. In 30 minutes after anastomosis, maximum blood pressure measured in the donor carotid arterial side when the recipient arterial wall was fasioned with the longitudinal slit was recorded 114 mmHg and with the triangular flap 100mmHg. Minimum blood pressure with the longitudinal slit was 98mmHg and with the triangular flap 88mmHg. The amount of blood collected for 30 seconds in the conventional longitudinal slit was 1.18mg and in the triangular flap 0.78mg. Histology study in 30 minutes, the conventional longitudinal slit demonstrated the more hemorrhagic features around the suture material compared to that of the triangular. flap and, in the 7th day, the conventional longitudinal slit demonstrated the more prominent granulomatous reactions and vascular proliferations around the suture material compared to that of the triangular flap.

• Proceedings of the Korean Society For Composite Materials Conference
• /
• 2000.11a
• /
• pp.92-97
• /
• 2000

Low-velocity impact damage of a thick pressure vessel by composite materials was studied using the modified Herzian contact radius theory. Impactors of various masses and various tup shapes were dropped freely in the range of 20m to 200mm height. With acceleration gage and strain gage installed on the impactor, impact force and acceleration and Contact radius were measured. After a test, the samples were radiographed to scan the state of damage. Compared with hemispherical tup of 12.7mm diameter, the contact radius of hemispherical tup of 25.4mm diameter was bigger. And the experimental data and the theoretical data was different due to the mechanical properties difference. The acceleration value was changed linearly according to the height.

• 한국신재생에너지학회:학술대회논문집
• /
• 2007.11a
• /
• pp.193-196
• /
• 2007

We developed and tested the high pressure hydrogen gas cylinder(type4) for fuel cell vehicle. The working pressure is 350bar. We conducted material tests, production tests and design qualification tests on the developed cylinders according to modified NGV2-2000(hydrogen). The high pressure hydrogen gas cylinder met all the design qualification requirements of ANSI/CSA NGV2-2000 and acquired NGV2 certification from independent inspection agency.

• Composites Research
• /
• v.23 no.6
• /
• pp.61-66
• /
• 2010

In this paper, the variation of mechanical properties of T800 carbon/epoxy composites according to the forming pressure, which was referred to previous studies on a filament winding process, were investigated. The specimens of all the tests were fabricated by an autoclave de-gassing molding process controlling forming pressure (absolute pressures of 0.1MPa, 0.3MPa, 0.7MPa including vacuum) and water jet cutting after fabricating composite laminates. Various tensile tests were performed for in-plane properties and interlaminar properties were also measured by using Iosipescu test jig. Fiber volume fraction was measured to correlate the property variation and the forming pressure. This properties are expected to be utilized in the design of Type III pressure vessel for hydrogen vehicles which uses the same carbon fiber (T800 carbon fiber) for the filament winding process.

• Composites Research
• /
• v.24 no.5
• /
• pp.23-28
• /
• 2011

In this paper, the bonding strengths of co-cured T800 carbon/epoxy composite-aluminum single lap joints with and without additional pressures were investigated using the pressure information induced by the fiber tension during a filament winding process. The specimens of all the tests were fabricated by an autoclave vacuum bag de-gassing molding being controlled forming pressures (absolute pressures of 0.1MPa, 0.3MPa and 0.7MPa including vacuum). A special device which can act uniform additional pressures on the joining part of the single lap joint specimen was designed to measure the bonding strengths of composite-aluminum liners of type III hydrogen pressure vessel fabricated by a filament winding process. After the three different additional pressures (absolute pressures of 0.1MPa, 0.3MPa and 0.7MPa) were applied to the specimens the effect of the additional pressures on the bonding strengths of the co-cured single-lap joints were evaluated.