• Structural Engineering and Mechanics
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• 제62권3호
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• pp.273-279
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• 2017

A meso-scale model is proposed to study filament-wound composites with fiber undulations and crossovers. First, the crossover and undulation region is classified as the circumferential undulation and the helical undulation. Next, the two undulations are separately regarded as a series of sub-models to describe the meso-structure of undulations by using meso-parameters such as fiber orientation, fiber inclination angle, resin rich area, fiber volume fraction and bundle cross section. With the meso-structure model and the classic laminate theory, a method for calculating the stiffness of filament wound composites is eventually established. The effects of the fiber inclination angle, the fiber and resin volume fraction and the resin rich area on the stiffness are studied. The numerical results show that the elastic moduli for the circumferential undulation region decrease to a great extent as compared with that of the helical undulation region. Moreover, significant decrease in the elastic and shear moduli and increase in the Poisson's ratio are also found for the resin rich area. In addition, thickness and bundle section have evident effect on the equivalent stiffness of the fiber crossover and the undulation region.

• 대한기계학회논문집A
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• 제29권8호
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• pp.1109-1117
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• 2005

To identify damage that develops in filament wound composite pressure vessels subjected to low velocity impact, a series of impact tests was performed on specimens cutting from the full scale pressure vessel. The resulting damages by the three different impactors were assessed by the scanning acoustic and metallurgical microscope. Based on the impact force history and damage, the resistance parameters were proposed and its validity in identifying the damage resistance of CFRP pressure vessel was reviewed. As the results, the impact resistance of the filament wound composites and its dependency on the impactor shape were estimated quantitatively.

• 한국안전학회지
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• 제20권4호
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• pp.14-19
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• 2005

One area in which composites have been used rather extensively is for fabricating pressure vessel. These structures can be readily manufactured by filament winding, which is, as far as composite fabrication techniques are concerned, a relatively inexpensive method for producing composite structures. Unfortunately, the higher strength material and fabrication costs are not the only disadvantages of fiber-reinforced polymer composites when they are compared to metals. Additionally, these materials tend to exhibit brittle behavior. This is of particular concern when they are subjected to a low-velocity impact during routine handling a significant amount of structural damage can be introduced into the composites. The goals of this paper are to understand the impact damage behavior and identify the effect of surface coating materials on impact resistance in filament wound composite pressure vessels. For these, a series of low velocity impact tests was performed on specimens cutting from the full scale pressure vessel by the instrumented impact testing machine. The specimens are classified into two types with and without surface protective material. The visualization for impact damage is made by metallurgical microscope. Based on the impact force history and damage, the resistance parameters were employed and its validity in identifying the damage resistance of pressure vessel was reviewed. As the results, the impact resistance of the filament wound composites and its dependency on the protective material were evaluated quantitatively.

• International Journal of Safety
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• 제4권2호
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• pp.6-11
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• 2005

The goals of the paper are to understand the impact damage behavior and identify the effect of surface protective materials on impact resistance in filament wound composite pressure vessels. For these, a series of low velocity impact tests was performed on specimens cutting from the full scale pressure vessel by the instrumented impact testing machine. The specimens are classified into two types, which are with and without surface protective material. The visualization for impact damage by two different impactors is made by metallurgical microscope. Based on the impact force history and damage, the impact resistance parameters were employed,rod its validity in identifying the damage resistance of filament wound composite pressure vessel was reviewed. As the results, the impact resistance of the filament wound composites and its dependency on the surface protective material were evaluated quantitatively

• 한국추진공학회지
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• 제3권2호
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• pp.56-65
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• 1999

본 연구에서는 와인딩시 공정조건의 변화가 필라멘트와인딩 복합재의 기계적 특성에 미치는 영향을 조사하였다. 와인딩시의 공정변수로는 섬유장력과 섬유엔드수를 고려하였다. 고려한 시편은 필라멘트와인딩 공법으로 제작된 링 시편으로 강화섬유는 TZ-507 탄소섬유와 IZ-40 탄소섬유를 사용하고 수지는 필라멘트와인딩용 에폭시를 사용하였다. 와인딩시 섬유장력은 0.5kgf에서 3.0kgf의 범위에서 변화시켰으며 섬유엔드수는 1엔드에서 6엔드의 범위에 서 변화시켰다. 와인딩시 섬유장력과 섬유엔드수를 변화시킨 링 시편의 섬유체적비와 기공함유율은 황산용해법을 적용하여 측정하였으며 이들 링 시편의 기계적 특성은 스프릿 디스크 시험을 통해 평가하였다. 본 연구의 수행을 통해 얻어진 결과들로 판단하면 와인딩시 섬유 장력과 섬유엔드수는 필라멘트와인딩 복합재의 섬유체적비와 기공함유율을 변화시킬 뿐 아니라 필라멘트 와인딩 복합재의 기계적 특성에도 밀접한 영향을 미친다. 따라서 필라멘트와인딩 복합재의 구조성능을 극대화하고 생산성을 향상시키기 위해서는 최적의 필라멘트 와인딩 공정조건이 적용되어야 한다.

• Journal of Advanced Marine Engineering and Technology
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• 제25권3호
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• pp.617-622
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• 2001

The purpose of this study is to design and the analyze the stress of composited shaft which is wound by filament winding method. The composites shaft has high strength and reduction in weight compared to metal shaft. The classical laminate plate theory(CLT) was used fro analysis the stress, and for structure design. In order to replace metal shaft by composites shaft, the diameter of shaft was determined to $\phi$ 40. The ration of diameter was determined to 0.4 for torsional moment with CLT. In this result of analyzing the stress, composites shaft was safe $30^{\circ}~60^{\circ}$C of winding angle, and was fractured on $90^{\circ}$.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2006년도 정기 학술대회 논문집
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• pp.3-9
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• 2006

Among many fabrication methods of composite materials, filament winding is the most effective method for fabricating axis-symmetric structures such as pressure tanks and pipes. Filament wound pressure tanks are under high internal pressure during the operation and it has the complexity in damage mechanisms and failure modes. Fiber optic sensors, especially FBG sensors can be easily embedded into the composite structures contrary to conventional electric strain gages (ESGs). In addition, many FBG sensors can be multiplexed in single optical fiber using wavelength division multiplexing (WDM) techniques. In this paper, we fabricated several filament wound pressure tanks with embedded FBG sensors and conducted some kinds of experiments such as an impact test, a bending test, and a thermal cycling test. From the experimental results, it was successfully demonstrated that FBG sensors are very appropriate to composite structures fabricated by filament winding process even though they are embedded into composites by multiplexing.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2000년도 추계학술대회 논문집(Proceeding of the KOSME 2000 Autumn Annual Meeting)
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• pp.15-20
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• 2000

Filament winding process is a comparatively simple operation in which continuous reinforcements in the form of roving are wound over a rotating mandrel. And it is now well established as a versatile method for storage tanks and pipe for the chemical and other industries. In this study, tensile strength of a filament wound ring specimens were evaluated by split disk test fixture and dress disk test fixture. The results obtained from experiments were compared with the theoretical values obtained by the rule of mixtures in composites . And the purpose of this paper is the suggestion of an appropriate test method for the evaluation of tensile properties of filament wound structures. The tensile strength of a ring specimen tested by the dress disk test showed better agreement with the theoretical values than that of a ring specimen tested by the split disk test because the stress concentration in edges of a split disk test fixture is more severe than that of dress disk test fixture. The results showed that the tensile strength of a ring specimen was influenced by the geometry of test fixture, the continuity of fibers, fiber-tension, fiber-end and stress concentration in specimen.

• 대한기계학회논문집
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• 제17권10호
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• pp.2407-2417
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• 1993

Thermal deformations and stresses due to temperature changes are the serious problems in cryogenic structures such as the torque tube in a superconducting generator, In this paper, the equations of thermal expansion coefficients expressed only by material properties and winding angles are derived for the filament wound composite tubes. The experimental results of thermal contraction of CFRP tubes are compared with those from theoretical approach. Composite tubes with optimally regulated thermal expansion coefficient are designed on the basis of the study for the torque tube in the superconducting generator with temperature distributions varying from 300K to 4.2 K. The filament winding angle of composites resisting thermal stresses properly is sought by the finite element method using layered shell elements. The results show that the composite tubes designed for the requirements in cryogenic environments can effectively cope with the thermal stress problem.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2001년도 춘계학술발표대회 논문집
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• pp.193-196
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• 2001

The purpose of this study is the design of composite shaft which is wound by Filament Winding method. Classical laminated plate theory was used for analyzing the stress, and for structure design. The diameter and thickness of composite shaft were calculated by this theory. The result that if tensile stress was zero, torsion stress was a certain value below 0.4(diameter rate) and torsion strength was the highest value on $45^{\circ}C$(winding angle). In case of $90^{\circ}C$(winding angle), we have to consider the torsional monent when the composites shaft was load.