Effects of oil absorption on the wear behaviors of carbon/epoxy woven composites

Jae-H. Lee,Jae-S. Lee,Kyong-Y. Rhee 한국탄소학회 2011 Carbon Letters Vol.12 No.4

Carbon/epoxy woven composites are prominent wear-resistant materials due to the strength, stiffness, and thermal conductivity of carbon fabric. In this study, the effect of oilabsorption on the wear behaviors of carbon/epoxy woven composites was investigated. Wear tests were performed on dry and fully oil-absorbed carbon/epoxy woven composites. The worn surfaces of the test specimens were examined via scanning electron microscopy to investigate the wear mechanisms of oil-absorbed carbon/epoxy woven composites. It was found that the oil absorption rate was 0.14% when the carbon/epoxy woven composites were fully saturated. In addition, the wear properties of the carbon/epoxy woven composites were found to be affected by oilabsorption. Specifically, the friction coefficients of dry and oil-absorbed carbon/epoxy woven composites were 0.25-0.30 and 0.55-0.6, respectively. The wear loss of the oilabsorbed carbon/epoxy woven composites was 3.52×10-2 cm3, while that of the dry carbon/epoxy woven composites was 3.52×10-2 cm3. SEM results revealed that the higher friction coefficient and wear loss of the oil-absorbed carbon/epoxy woven composites can be attributed to the existence of broken and randomly dispersed fibers due to the weak adhesion forces between the carbon fibers and the epoxy matrix.

열전도도 향상을 위한 직물섬유 복합재의 최적구조 설계

김명수 ( Myungsoo Kim ),성대한 ( Dae Han Sung ),박영빈 ( Young Bin Park ),박기원 ( Kiwon Park ) 한국복합재료학회 2017 Composites research Vol.30 No.1

본 연구에서는 직물섬유 복합재의 열전도를 구하는데 있어 기존의 연구보다 개선된 방법을 제시하고, 직물섬유의 기하학적 구조가 복합재의 열전도도 향상에 미치는 영향, 그리고 유전 알고리즘(Genetic algorithm)을 이용하여 복합재의 열전도도 향상을 위한 최적구조 설계에 관한 연구를 하였다. 직물섬유의 구조를 토우의 물결무늬와 너비 및 두께를 이용하여 구현하였고, 열전도도는 열전기유사법(Thermal-electrical analogy)을 이용하여 구하였다. 유전 알고리즘에서 염색체 문자열은 fill과 warp tow의 두께와 너비로 하였고 복합재의 열전도도를 향상 시키는 방향으로 목적함수를 정하였다. 연구결과 직물섬유 복합재의 열전도도를 예측을 위한 향상된 방법이 제시되었고, 섬유토우 사이의 간격(inter-tow gap)이 넓어 질수록 복합재의 열전도도가 감소하는 것으로 나타났다. 직물섬유 복합재의 구조 최적화에서는 이론적 수치해석 결과가 제시되었는데, 전체적으로 섬유토우(tow)의 축의 수직 방향보다는 축 방향의 열전도도 성분이 복합재의 전체 열전도도 향상에 크게 기여를 하는 것으로 나타났다. This research presents studies on an improved method to predict the thermal conductivity of woven fabric composites, the effects of geometric structures of woven fabric composites on thermal conductivity, and structural optimization to improve the thermal conductivity using a genetic algorithm. The geometric structures of woven fabric composites were constructed numerically using the information generated on waviness, thickness, and width of fill and warp tows. Thermal conductivities of the composites were obtained using a thermal-electrical analogy. In the genetic algorithm, the chromosome string consisted of thickness and width of the fill and warp tows, and the objective function was the maximum thermal conductivity of woven fabric composites. The results confirmed that an improved method to predict the thermal conductivity was built successfully, and the inter-tow gap effect on the composite`s thermal conductivity was analyzed suggesting that thermal conductivity of woven fabric composites was reduced as the gap between tows increased. For structural design, optimized structures for improving the thermal conductivity were analyzed and proposed. Generally, axial thermal conductivity of the fiber tow contributed more to thermal conductivity of woven fabric composites than transverse thermal conductivity of the tows.

Effect of Pile Height on the Mechanical Properties of 3D Woven Spacer Composites

Muhammad Umair,Syed Talha Ali Hamdani,Yasir Nawab,Muhammad Ayub Asghar,Tanveer Hussain,Abdelghani Saouab 한국섬유공학회 2019 Fibers and polymers Vol.20 No.6

Three-dimensional (3D) woven spacer fabric is produced by connecting two woven fabric layers with the verticalpile yarns in the center part. Their composites have great potential for use in construction, automotive, marine, and aerospaceapplications due to outstanding mechanical properties. In this paper, 3D woven spacer fabrics with three thickness levels(4 mm, 10 mm and 20 mm) made of E-glass fibre, were used. Then 3D woven spacer fabrics were fabricated into theircorresponding composites by hand lay-up technique using green epoxy resin. Characterization was done at both stages i.e. fabric and composite. Bending length and modulus of 3D woven spacer fabrics were decreased while the stiffness of thefabric was increased with increase in sample thickness. While in 3D woven spacer composites, 20 mm thick composite wasmore needle penetration resistant as compared to the 10 mm and 4 mm thick composites. Flexural and slow velocity impactperformance of the 3D woven spacer composites was reduced with the increase of sample thickness. Flexural behaviour wasbetter in weft direction as compared to the warp direction in all samples. Furthermore, 4 mm thick composite showed thehighest value of energy absorbed and least deformation during the drop weight impact test.

열가소성 직물탄소복합소재 사출 성형품의 표면 함침 개선에 관한 연구

정의철,윤경환,이성희,Jeong, Eui-Chul,Yoon, Kyung-Hwan,Lee, Sung-Hee 한국금형공학회 2021 한국금형공학회지 Vol.15 No.3

In molding of continuous fiber-reinforced thermoplastic composites, it is very difficult to impregnate between the reinforcements and the matrix since the matrix has a high melting temperature and high viscosity. Therefore, most of composite molding processes are divided in the manufacturing processes of intermediate materials called prepreg and the forming of products from intermediate materials. The divided process requires additional facilities and thermoforming, and they increase the cycle time and cost of composite products. These problems can be resolved by combining the continuous fiber-reinforced composite molding process with injection molding. However, when a composite material is manufactured by inserting woven fabric into the injection mold, poor impregnation occurs on the surface of the molded product. It affects the properties of the composites. In this paper, through an impregnation experiment using cores with different heat transfer rates and pore densities, the reason for the poor impregnation was confirmed, and molding experiments were conducted to produce composite with improved surface impregnation by inserting the mesh. And also, the surface impregnation and deformation of composites molded using different types of mesh were compared with each other.

직조 복합재료의 구조적 특성을 고려한 모델링 기법 및 물성 예측 기법 개발

최경희,황연택,김희준,김학성 한국복합재료학회 2019 Composites research Vol.32 No.5

As the use of composite materials of woven structure has expanded to various fields such as automobile and aviation industry, there has been a need for reliability problems and prediction of mechanical properties of woven composites. In this study, finite element analysis for predicting the mechanical properties of composite materials with different weaving structures was conducted to verify similarity with experimental static properties and an effective modeling method was developed. To reflect the characteristics of the weave structure, the meso-scale representative volume element (RVE) was used in modeling. Three-dimensional modeling was carried out by separating the yarn and the pure matrix. Hashin’s failure criterion was used to determine whether the element was failed, and the simulation model used a progressive failure model which was suitable for the composite material. Finally, the accordance of the modeling and simulation technique was verified by successfully predicting the mechanical properties of the composite material according to the weave structure. 직조 구조의 복합재의 쓰임이 자동차, 항공 산업 등 여러 분야로 확장됨에 따라, 직조 복합재의 신뢰성 문제 및 물성예측에 대한 필요성이 대두되었다. 본 연구에서는 직조 구조가 다른 복합재료의 물성 예측을 위한 유한요소해석을 수행하여 실험으로 얻은 정적 물성과의 유사성을 검증하였고, 효과적인 모델링 방법을 개발하였다. 직조 구조의 특성을 반영하기 위하여 모델링은 메소 스케일의 대표 체적 요소(RVE)를 이용하였다. 섬유 다발과 순수 기지를 분리하여 3차원 모델링을 진행하였다. 하신 파괴 기준(Hashin’s failure criteria)을 적용하여 요소의 파괴 유무를 판단하였고, 해석 모델은 복합재에 적합한 점진적 파괴 모델을 사용하였다. 최종적으로, 직조 구조에 따른 복합재의 물성을 성공적으로 예측하여 본 모델링 및 해석 기법에 대한 적합성을 검증하였다.

Mechanical Analysis of Woven Composites Through Experimental Investigation and Multiscale Numerical Simulation

Guangqiang Fang,Peng Qu,Zhengli Cao,Feizhou Shi 한국섬유공학회 2022 Fibers and polymers Vol.23 No.5

In this paper, the mechanical properties of a single-ply woven composites are investigated through a combinationof multiscale numerical simulation and experimental test. The tensile experiments of three woven structures with differentthread counts, 4.5+4.0, 5.5+7.0 and 5.5+5.0, are conducted. A multiscale numerical method is proposed in order tounderstand the influence mechanism of thread count on the mechanical properties. The numerical predictions have a goodagreement with the experimental results. Many unique characteristics of the single-ply woven composites have beenobserved, such as the clearly nonlinear mechanical behavior of samples with large thread count, the positive transversalnormal strain during the initial phase of longitudinal uniaxial tension and the breakage morphology in relation to threadcount. The M/L ratio is proposed in this paper to investigate the effect of the difference in the thread count between warp andfill direction on the mechanical behavior. The M/L ratio of thread count of 5.5+7.0 specimen is larger than 4.5+4.0 and5.5+5.0 by 38 % and 41 %, respectively, the corresponding M/T ratio of modulus is larger by 34 % and 29 %, and for strengthit is 23 % and 24 %. It is found that the increase of thread count in one direction improves the mechanical properties in thisdirection but reduces the equivalent elastic modulus and strength in the vertical direction. The simulated stress and straindistribution inside the RUC helps to better understand the influence mechanism of thread count on the mechanical propertiesof single-ply woven composites.

Evolution of 3D weaving and 3D woven fabric structures

Yasith Sanura Perera,Rajapaksha Mudiyanselage Himal Widooshaka Muwanwella,Philip Roshan Fernando,Sandun Keerthichandra Fernando,Thantirige Sanath Siroshana Jayawardana 한국의류학회 2021 Fashion and Textiles Vol.8 No.1

3D fabric preforms are used as reinforcements in composite applications. 3D woven preforms have a huge demand in ballistic applications, aircraft industry, automobiles and structural reinforcements. A variety of 3D woven fabric reinforced composites and two dimensional woven fabric reinforced laminates can be found in the literature. However, the majority of the said products lack in delamination resistance and possess poor out-of-plane mechanical characteristics, due to the absence or insufficiency of through-thickness reinforcement. 3D fully interlaced preform weaving introduces a method of producing fully interlaced 3D woven fabric structures with throughthickness reinforcement, which enhances the delamination resistance as well as out-of-plane mechanical characteristics. 3D woven fabric preforms made from 3D fully interlaced preform weaving, using high-performance fiber yarns such as Dyneema, Carbon, Kevlar and Zylon, have exceptional mechanical properties with light-weight characteristics, which make them suitable candidates for high-end technical composite applications. In this work, a brief introduction is given to the history of weaving followed by an introduction to 3D woven fabrics. In the existing literature, an emphasis is given to the 3D fully interlaced preform weaving process, distinguishing it from other 3D woven fabric manufacturing methods. Subsequently, a comprehensive review is made on the existing literature on 3D fully interlaced preform weaving devices, such as primary and secondary mechanisms as well as modelling of 3D woven fabric structures produced by 3D fully interlaced preform weaving. Finally, the authors attempted to discuss the existing research gaps with potential directions for future research.

Effects of Face Sheet Structure on Mechanical Properties of 3D Integrated Woven Spacer Composites

Man Zhang,Xiaoxue Wang,Shuqiang Liu,Fu Li,Gaihong Wu 한국섬유공학회 2020 Fibers and polymers Vol.21 No.7

Due to the lightweight, structural integrity, superior heat and sound insulation performance, three-dimensional(3D) integrated woven spacer composites are expected to be used in many fields such as marine, automotive, electronics, andbuilding industries. This paper reports the effects of face sheet structure on the mechanical properties of 3D integrated wovenspacer composites. Three-point bending, quasi-static compression and low-velocity impact tests were conducted to comparethe mechanical responses of 3D woven spacer composites with plain and complex face sheets. The floating yarn segments incomplex face sheet could efficiently transfer the stress to neighboring areas and lead to a more balanced stress distribution. The existence of floats thus has positive effect on mechanical properties of composites. On the contrary, plain structuresurface was dense and the stress transfer was easily hindered by numerous weaving points, resulting in stress concentrationand ultimate premature failure. As a consequence, for surface-dominated properties such as warp-direction bending andimpact resistance, 3D integrated woven spacer composites with complex surface is better and should be given priority duringindustrial applications. In terms of weft-direction bending property and quasi-static compressive performance, which moredepend on the structure of core piles, show little difference between the composites with different surfaces.

Experimental and numerical FEM of woven GFRP composites during drilling

Mohamed S. Abd-Elwahed,Usama A. Khashaba,Khaled I. Ahmed,Mohamed A. Eltaher,Ismael Najjar,Ammar Melaibari,Azza M. Abdraboh 국제구조공학회 2021 Structural Engineering and Mechanics, An Int'l Jou Vol.80 No.5

This paper investigates experimentally and numerically the influence of drilling process on the mechanical and thermomechanical behaviors of woven glass fiber reinforced polymer (GFRP) composite plate. Through the experimental analysis, a CNC machine with cemented carbide drill (point angles =118° and 6 mm diameter) was used to drill a woven GFRP laminated squared plate with a length of 36.6 mm and different thicknesses. A produced temperature during drilling “heat affected zone (HAZ)” was measured by two different procedures using thermal IR camera and thermocouples. A thrust force and cutting torque were measured by a Kistler 9272 dynamometer. The delamination factors were evaluated by the image processing technique. Finite element model (FEM) has been developed by using LS-Dyna to simulate the drilling processing and validate the thrust force and torque with those obtained by experimental technique. It is found that, the present finite element model has the capability to predict the force and torque efficiently at various drilling conditions. Numerical parametric analysis is presented to illustrate the influences of the speeding up, coefficient of friction, element type, and mass scaling effects on the calculated thrust force, torque and calculation’s cost. It is found that, the cutting time can be adjusted by drilling parameters (feed, speed, and specimen thickness) to control the induced temperature and thus, the force, torque and delamination factor in drilling GFRP composites. The delamination of woven GFRP is accompanied with edge chipping, spalling, and uncut fibers.

Improved Modeling Method for 3-Dimensional Woven Composites Using Weaving Parameters

Hiyeop Kim,박정선 한국항공우주학회 2021 International Journal of Aeronautical and Space Sc Vol.22 No.4

To model 3-Dimensional woven composites, the width and thickness of the yarn are generally used as input parameters. However, since these parameters can only be obtained after the composites are molded, it is not efficient in the initial stages of design using woven composites. Therefore, a geometric modeling method using weaving parameters that can be known before manufacturing is required. In this paper, geometric parameters such as thickness and width of each yarn are calculated using weaving parameters. From the obtained parameters, the cross section and path of the yarns and the unit cell are modeled. The method is validated by comparing the calculated geometric parameters and fiber volume fraction with direct measurements of the overall composite. Moreover, the unit cell is applied to an analytical method based on the iso-strain and iso-stress assumptions to evaluate the stiffness in the longitudinal and transverse directions. The mechanical properties are compared and verified with the specimen test results. We conclude that the present method is useful for the design of aerospace structures to which the 3-dimensional composite is applied.