• Geomechanics and Engineering
• /
• v.5 no.2
• /
• pp.87-97
• /
• 2013

In this paper, a novel fibrous material known as axially reinforced braided composite rods (BCRs) have been developed for reinforcement of soils. These innovative materials consist of an axial reinforcement system, comprised of longitudinally oriented core fibres, which is responsible for mechanical performance and, a braided cover, which gives a ribbed surface texture for better interfacial interactions with soils. BCRs were produced using both thermosetting (unsaturated polyester) and thermoplastic (polypropylene) matrices and synthetic (carbon, glass, HT polyethylene), as well as natural (sisal) core fibres. BCRs were characterized for tensile properties and the influence of core fibres was studied. Moreover, BCRs containing carbon fibre in the core composition were characterized for piezoresistivity and strain sensing properties under flexural deformation. According to the experimental results, the developed braided composites showed tailorable and wide range of mechanical properties, depending on the core fibres and exhibited very good strain sensing behavior.

• Proceedings of the Korean Society For Composite Materials Conference
• /
• 2003.10a
• /
• pp.71-74
• /
• 2003

The cell modeling homogenization method to derive the constitutive equation considering the microstructures of the fiber reinforced composites has been previously developed for composites with simple microstructures such as 2D plane composites and 3D rectangular shaped composites. Here, the method has been further extended for 3D circular braided composites, utilizing B-spline curves to properly describe the more complex geometry of 3D braided composites. For verification purposes, the method has been applied for orthotropic elastic properties of the 3D circular braided glass fiber reinforced composite, in particular for the tensile property. Prepregs of the specimen have been fabricated using the 3D braiding machine through RTM (resin transfer molding) with epoxy as a matrix. Experimentally measured uniaxial tensile properties agreed well with predicted values obtained fer two volume fractions.

• Proceedings of the Korean Society For Composite Materials Conference
• /
• 2003.04a
• /
• pp.184-187
• /
• 2003

Complete prediction of second order permeability tensor for three dimensional circular braided preform is critical to understand the resin transfer molding process of composites. The permeability can be predicted by considering resin flow through the multi-axial fiber structure. In this study, permeability tensor for a 3-D circular braided preform is calculated by solving a boundary problem of a periodic unit cell. Flow field through the unit cell is obtained by using a 3-D finite volume method (FVM) and Darcy's law is utilized to obtain permeability tensor. Flow analysis for two cases that a fiber tow is regarded as impermeable solid and permeable porous medium is carried out respectively. It is found that the flow within the intra-tow region of the braided preform is negligible if inter-tow porosity is relatively high but the flow through the tow must be considered when the porosity is low. To avoid checkerboard pressure field and improve the efficiency of numerical computation, a new interpolation function for velocity variation is proposed on the basis of analytic solutions. Permeability of the braided preform is measured through a radial flow experiment and compared with the permeability predicted numerically.

• Journal of the Korean Society of Costume
• /
• v.66 no.3
• /
• pp.135-146
• /
• 2016

This study is examines the replica of the excavated braided belt that tied the Daedae(大帶) of Simui(深衣). This study aims to comprehend the structure and color of the excavated braided belt, and to reproduce the Jodae(braided belt) of Kim Won-taek(1683-1766) clan, which was excavated in Cheongju. Black dye was used on the belt since it was the color that remained the most on the artifact. This study in the color black is focused on the Cheungchosack in Jeonggongji(展功志) from the first volume of 'Yimwongyeongjeji(林圓經濟志)'. From the Kim Won-taek clan, the braided belt of Simui of Kim Won-taek and his son, Kim Shang-jik(1716-1773), have been excavated. The blackness of the braided belt was more apparent in Kim Shang-jik compared to Kim Won-taek, and also Kim Shang-jik's braided belt was darkbrown. So I mixed gallnut, green vitriol, ash tree and catechu, the ingredient of bluish black, in equal proportions. Kim Won-taek's silk thread was dyed 3 times and Kim Sang-jik's silk thread was dyed 5 times to reproduce the original belt. Based on the information from the 'Saryepyenlam(四禮便覽)' that the Jo was weaved with five colored threads, I reproduced the Jo with sophora flowers, gardenia, amur cork tree, safflower, madder and indigo sediment. Yeokeum organization(interlacing), which is a Jodae woven strands of both sets of 15 repeats construction were in the mixed organization of 3/2 and 2/2.

• Fibers and Polymers
• /
• v.4 no.2
• /
• pp.77-83
• /
• 2003

The cell modeling homogenization method to derive the constitutive equation considering the microstructures of the fiber reinforced composites has been previously developed for composites with simple microstructures such as 2D plane composites and 3D rectangular shaped composites. Here, the method has been further extended for 3D circular braided com-posites, utilizing B-spline curves to properly describe the more complex geometry of 3D braided composites. For verification purposes, the method has been applied for orthotropic elastic properties of the 3D circular braided glass fiber reinforced com-posite, in particular for the tensile property. Prepregs of the specimen have been fabricated using the 3D braiding machine through RTM (resin transfer molding) with epoxy as a matrix. Experimentally measured uniaxial tensile properties agreed well with predicted values obtained for two volume fractions.

• Proceedings of the Korean Society For Composite Materials Conference
• /
• 2002.10a
• /
• pp.114-117
• /
• 2002

To develop an effective geometric modeling is essential in order that precise material properties of the 3-D braided composite can be estimated. in this study RVE(representative volume element) which is the smallest volume element representing whole material properties is developed to estimate the mechanical properties of 3-D flat board shaped braided composite using volume averaging method.

• Proceedings of the Korean Society For Composite Materials Conference
• /
• 2002.10a
• /
• pp.68-70
• /
• 2002

Prediction of 3-D permeability tensor for multi-axial preform is critical to model and design the manufacturing process of composites by considering resin flow through the multi-axial fiber structure. In this study, the in-plane and transverse permeabilities for braided preform are predicted numerically. The flow analyses are calculated by using 3-D CVFEM(control volume finite element method) for macro-unit cells. To avoid checker-board pressure field and improve the efficiency of numerical computation, a new interpolation function for velocity is proposed on the basis of analytic solutions. Permeability of a braided preform is measured through unidirectional flow experiment and compared with the permeability calculated numerically. Unlike other studies, the current study is based on more realistic unit cell and prediction of permeability is improved.

• Proceedings of the Korean Society For Composite Materials Conference
• /
• 2003.10a
• /
• pp.83-86
• /
• 2003

Complete prediction of second order permeability tensor for three dimensional preform such as plain woven fabric and braided preform is critical to understand the resin transfer molding process of composites. The permeability can be obtained by various methods such as analytic, numerical, and experimental methods. For several decades, the permeability has studied numerically to avoid practical difficulty of many experiments. However, the predicted permeabilities are a bit wrong compared with experimentally measured data. In this study, numerical calculation of permeability was conducted for two kinds of preforms i.e., plain woven fabric and circular braided preform. In order to consider intra-tow flow in the unit cell of preform the proposed flow coupled model was used for plain woven fabric and the Brinkman equation was solved in the case of the braided preform.

• Korea-Australia Rheology Journal
• /
• v.19 no.1
• /
• pp.17-25
• /
• 2007

In liquid composite molding (LCM), composites are produced by impregnation of a dry preform with liquid resin. The resin flow through the preform is usually described by Darcy's law and the permeability tensor must be obtained for filling analysis. While the resin flow in the thickness direction can be neglected for thin parts, the resin flow in the transverse direction is important for thicker parts. However, the transverse permeability of the preform has not been investigated frequently. In this study, the transverse permeability was measured experimentally for five different fiber preforms. In order to verify the experimental results, the measured transverse permeability was compared with numerical results. Five different fiber mats were used in this study: glass fiber woven fabric, aramid fiber woven fabric, glass fiber random mat, glass fiber braided preform, and glass/aramid hybrid braided preform. The anisotropic braided preforms were manufactured by using a three dimensional braiding machine. The pressure was measured at the inlet and outlet positions with pressure transducers.

• Journal of the Korean Society of Costume
• /
• v.66 no.5
• /
• pp.133-148
• /
• 2016

This study examined dahoe(多繪-braided cord) and mangsu(網綬-ornament of husu for ceremonial dress) used in myeon gwan(冕冠), daedae(大帶), and husu(後綬) among royal formal dresses in the Joseon Dynasty(1392-1910) based on historical materials including literature, relics, and paintings. The results of this study are as follows. In myeon-gwan, dahoe was used for cap strings, goeing(紘) and yeong(纓). Cap strings were applied to the king, the Crown Prince, and the eldest son of the Crown Prince regardless of their status, and they showed differences among the periods. Both goeing and yeong were used during the early period of Joseon, and then only yeong was used in the late period. As goeing was removed and only yeong was used in the late period, patterns combining goeing and yeong, in color and wearing method, appeared. Dahoe used in cap strings is dongdahoe(童多繪-a kind of braided cord). In daedae, 'nyuyak(紐約)' was tied up to its fastening part. The material of nyuyak was changed from dongdahoe in the early Joseon Dynasty to guangdahoe(廣多繪-a kind of braided cord) in the late period, and the method of using it was also changed. Husu was imported from Beijing in China during the early period of the Joseon Dynasty, but in 1747, it was regulated to be woven in Joseon, and at that time, King Yeongjo attempted to restore the institution of weaving husu with "320 su(首)," namely, 6,400 strands as specified for the status of a prince of the Ming Dynasty.