• Title/Summary/Keyword: MWK composites

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Analysis of Structure and Prediction of Mechanical Properties for 3D Composites (3D 복합재료의 구조해석 및 기계적 물성 예측)

  • 유근수;전흥재;변준형;이상관
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2002.10a
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    • pp.292-295
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    • 2002
  • In this paper, an analytical model for the prediction of the elastic properties of multi-axial warp knit fabric (MWK) composites is proposed. The geometric limitation, effect of stitching fibers and design parameters of MWK composites are considered in the model. The elastic behavior of MWK composites was conducted by using an averaging method. The predicted elastic properties are in reasonably good agreement with experimental values. Finally the effect of stitching in the MWK composites are discussed.

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Mechanical Behaviors of Multi-Axial 'Warp Knitted Fabric Composites (다축경편 복합재료의 거동에 관한 연구)

  • Kim Hyung-Woo;Chun Heoung-Jae;Byun Joon-Hyung
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2004.10a
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    • pp.198-202
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    • 2004
  • An analytical model using expanded bridging model was proposed to predict the elastic properties and behaviors of stitched multi-axial warp knitted (MWK) fabric composites, The characteristics of MWK fabric composites are the assemblage of multi-layers of fiber bundles for in-plane reinforcement and stitch yams for the through-the-thickness reinforcement. In the analysis, a representative volume of the MWK fabric composite was identified, The geometric limitations, effects of stitching yams and design parameters of MWK fabric composites were considered in the model. Then, the elastic properties and behaviors of MWK fabric composites were predicted, Finally, the results of proposed model of the composites were verified through the experiments, The predicted results were in fair agreement with the experimental results

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Predictions of elastic properties of stitched multi-warped knitted composites (다축경편 복합재료 물성의 스티칭 효과)

  • Kim, Hyung-Woo;Chun, Heoung-Jae;Byun, Joon-Hyung
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2005.04a
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    • pp.125-129
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    • 2005
  • A micromechanical model for predicting the elastic constants of stitched multi-axial warp knitted (MWK) composite is developed. The averaging method is used to obtain effective properties of stitched MWK fabric composites. In the analysis, a representative volume of the MWK fabric composite is identified. The geometric limitations, effects of stitching yarns and design parameters of MWK fabric composites are considered in the model. Then, the elastic properties of stitched MWK fabric composites are predicted. Finally, the predicted elastic constants are validated by comparison with experimental data. The predicted results are in fair agreement with the experimental results.

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Stitching Effect on Flexural and Interlaminar Properties of MWK Textile Composites

  • Byun, Joon-Hyung;Wang, Yi-Qi;Um, Moon-Kwang;Lee, Sang-Kwan;Song, Jung-Il;Kim, Byung-Sun
    • Composites Research
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    • v.28 no.3
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    • pp.136-141
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    • 2015
  • The stitching process has been widely utilized for the improvement of through-thickness property of the conventional laminated composites. This paper reports the effects of stitching on the flexural and interlaminar shear properties of multi-axial warp knitted (MWK) composites in order to identify the mechanical property improvements. In order to minimize the geometric uncertainties associated with the stacking pattern of fabrics, the regular lay-up was considered in the examination of the stitching effect. The key parameters are as follows: the stitch spacings, the stitching types, the stitching location, and the location of compression fixture nose. These parameters have little effect on the flexural and interlaminar shear properties, except for the case of stitching location. However, the geometry variations caused by the stitching resulted in minor changes to the mechanical properties consistently. Stitching on the $0^{\circ}$ fibers showed the lowest flexural strength and modulus (12% reduction for both properties). The stitch spacing of 5 mm resulted in 8% reduction for the case of interlaminar strength compared with that of 10 mm spacing.

Stress Analysis of Mechanically Fastened Joints in MWK Composite Laminate with Different Geometric :Factors and Loading Conditions (다축경편 복합재료 평판의 기계적 체결시 기하학적 형상 및 하중조건에 다른 응력해석)

  • Choi J.-M.;Jo M.-G.;Chun H.-J.;Byun J.-H.
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2004.04a
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    • pp.246-249
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    • 2004
  • When MWK (Multiaxial Warp Knitted Fabric) composites are applied for the structures, the connections of each component using mechanical fastening is needed. The local contact between the bolted joint and the composite laminates may induce high stress concentration or breakdown in the laminates for the mechanical joints. There for, it is strongly required to study the characteristics of mechanically joints of MWK composite laminates. In this study, stress analysis near the hole boundary of MWK composite laminate is conducted with various geometric factors under different loadings. In the case of multi-pin loaded MWK composite laminates, the results show that the types of loadings and geometric factors of mechanical joints have a significant influence on the joint performances.

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Characterization of Stitched Multiaxial Warp Knit Fabric Composites and Channel Beam Manufacturing (Stitched 다축경편 복합재료의 기계적 특성 및 U 빔 성형)

  • 변준형;이상관;엄문광;김태원;배성우;하동호
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2002.10a
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    • pp.280-283
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    • 2002
  • In the manufacturing of large scale composite structures, the cost-effective processing and the enhancement of structural performance are critical. One of the most effective ways for this purpose is to use stitched multiaxial warp knitted (MWK) perform in the resin transfer molding process. This study reports the effect of stitching on the mechanical properties of MWK composites, and the feasibility processing of the thick U-beam structure utilizing the stitched preforms. Permeability of the preform, viscosity and cure property of the epoxy resin have been measured. The results of resin flow analysis has been used in determining the gate/vent locations of the RTM mold. Cross-sectional observation of the channel beam prototype demonstrated that the resin impregnation was almost complete, except for some surrounding area of stitched yarns.

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Impact Properties of S-2 Glass Fiber Composites with Multi-axial Structure (다축 구조 S-2 유리섬유 복합재의 충격 특성)

  • Song, S.W.;Lee, C.H.;Byun, J.H.;Hwang, B.S.;Um, M.K.;Lee, S.K.
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2005.04a
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    • pp.71-75
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    • 2005
  • For the damage tolerance improvement of conventional laminated composites, stitching process have been utilized for providing through-thickness reinforcements. 2D preforms were stacked with S-2 glass plain weave and S-2 glass MWK (Multi-axial Warp Knit) L type. 3D preforms were fabricated using the stitching process. All composite samples were fabricated by RTM (Resin Transfer Molding) process. To examine the damage resistance performance the low speed drop weight impact test has been carried out. For the assessment of damage after the impact loading, specimens were examined by scanning image. CAI (Compressive After Impact) tests were also conducted to evaluate residual compressive strength. Compared with 2D composites, the damage area of 3D composites was reduced by 20-30% and the CAI strength showed 5-10% improvement.

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