• Title/Summary/Keyword: 보강된 복합재 구조

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Buckling Analysis of Laminated Composite Plates Longitudinally Stiffened with U-Shaped Ribs (축방향 압축을 받는 폐단면리브로 보강된 복합적층판의 좌굴 해석연구)

  • Choi, Byung-Ho;Choi, Su-Young;Park, Sang-Kyun
    • Journal of the Korean Society for Advanced Composite Structures
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    • v.3 no.1
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    • pp.29-34
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    • 2012
  • Even though the longitudinally stiffened laminated composite plates with closed section ribs should be an effective system for axially compressed members, the existing researches on the applications of closed-section ribs, especially for the laminated composite plates, are not sufficient. This study is aimed to examine the influence of the sectional stiffness of U-shaped ribs on the buckling modes and strengths of laminated composite plates. Applying the orthotropic plates with eight layers of the layup $[(0^{\circ})_4]_s$ and $[(0^{\circ}/90^{\circ})_2]_s$, 3-dimensional finite element models for the U-rib stiffened plates were setup by using ABAQUS and then a series of eigenvalue analyses were conducted. From the parametric studies, the minimum required ply thicknesses as well as the buckling strengths were presented for the analysis models. The buckling strengths were compared with the theoretical critical stress equation for simply supported plates based on the Classical laminated plate theory. This study will contribute to the future study for evaluating the minimum required stiffness and optimum design of U-rib stiffened plates.

Experimental Method for Evaluating Debonding Strength of FRPs Used for Retrofitting Concrete Structures (콘크리트 휨부재 보강용 FRP의 부착성능 평가를 위한 실험방법 연구)

  • Utui, Nadia;Kim, Hee-Sun
    • Journal of the Korean Society for Advanced Composite Structures
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    • v.2 no.3
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    • pp.36-41
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    • 2011
  • This study proposes a experimental method to evaluate bonding strength of FRPs used for retrofitting concrete structures. Specimens are designed so that debonding failure of FRPs can be induced from reinforced concrete beams retrofitted with two layers of carbon and glass FRPs. And three-point loading tests are performed to see if debonding failure with proper debonding strength is observed from the specimens. The test results show that the tested beams are failed due to debonding of FRPs, therefore, the proposed test method is capable of evaluating debonding strength of FRPs using relatively small normal strength concrete beams.

Prediction of Thermal Conductivity of Spatially Reinforced Composites (다방향으로 입체 보강된 복합재의 열전도계수 예측)

  • 이상의;유재석;김천곤;홍창선;김광수
    • Composites Research
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    • v.14 no.3
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    • pp.57-68
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    • 2001
  • This paper predicted the thermal conductivity of spatially reinforced composites(SRC) by applying the volume averaging method and the thermal resistance method. The former method employs existing micro-mechanical theories and conventional transformation rules to obtain the constitutive relations for the unit cells of the composites and the latter one uses the analogy between the diffusion of heat and electrical charge. To verify the theoretical predictions, the thermal conductivity of 4-D(dimensional) SRC was examined experimentally. The comparison of the numerical results with those measured by the experiment showed good agreement.

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Strength of Stainless Steel Pin-reinforced Composite Single-lap Joints (금속 핀으로 보강된 복합재 단일겹침 체결부의 강도 연구)

  • Lee, Byeong-Hee;Park, Yong-Bin;Kweon, Jin-Hwe;Choi, Jin-Ho;Choi, Ik-Hyeon;Chang, Sung-Tae
    • Composites Research
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    • v.25 no.3
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    • pp.65-69
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    • 2012
  • The main objective of this study is to investigate the effect of metal z-pinning on the failure behavior of cocured composite single-lap joints. Three different pin diameters (0.3, 0.5, and 0.7 mm) and three pin areal densities (0.5, 2.0, and 4.0%) were examined. The specimens were fabricated by T700-12K-31E#2510 unidirectional prepreg from Toray. Stainless steel pins were used for z-pinning. Test results showed that except one case with extremely low pin density of 0.5%, all other z-pinned joints exhibited lower initial crack stresses than those of the unpinned joint. However the ultimate strength of the z-pinned joint increased up to 45% at most. Furthermore, even after the complete failure of the joint, the z-pins sustained the carried load to a certain degree experiencing large deformation and provided the stable fracture behavior for the composite joint.

Effect of Composite Re-bars Embedded in Concrete on Surface Electrical Resistivity of Concrete (콘크리트내 섬유복합체 보강근이 표면저항치에 미치는 영향)

  • Moon, Do Young
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.15 no.6
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    • pp.212-218
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    • 2011
  • The effect of composite reinforcing bars on surface electrical resistivity of concrete was investigated through experimental program. The resistivity was measured by Wenner method using an equipment with 4 probe. Ordinary steel, GFRP, and CFRP reinforcing bars produced domestically were used and a specimen with no reinforcement was tested for the comparison. This investigation is motivated from the fact that measured value of resistivity of concrete is significantly affected by details of steel reinforcements, such as location, depth and direction of the internal steel reinforcement. These results could be valuable data for evaluation of corrosion degree of concrete structures reinforced or strengthened by the composite reinforcing bars.

Stiffness Prediction of Spatially Reinforced Composites (공간적으로 보강된 복합재료의 강성예측)

  • 유재석;장영순;이상의;김천곤
    • Composites Research
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    • v.17 no.5
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    • pp.25-38
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    • 2004
  • In this study, the stiffness of spatially reinforced composites (SRC) are predicted by using superposition of a rod and matrix stiffnesses in an arbitrary direction. To confirm the predicted values, the material properties of SRC are measured. The predicted values from the volume average of stiffness matrix are consistent with the tested values in a rod direction, but are inconsistent in an off-rod direction while reverse is true fur the volume average of compliance matrix. Therefore, the harmony function from superposition of stiffness and compliance matrix is introduced. The predicted values from the harmony function are consistent with the tested values in both the rod and the off-rod directions.

Studying on the Hybrid FRP Stiffener for the Performance Improvement of Strengthened RC Beam (철근콘크리트 보의 성능개선을 위한 Hybrid FRP 보강재 연구)

  • Ahn, Mi-Kyoung;Lee, Sang-Moon;Jung, Woo-Young
    • Proceedings of the Korea Concrete Institute Conference
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    • 2010.05a
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    • pp.243-244
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    • 2010
  • Reinforced concrete beam are very diverse materials that are used to bending reinforcement. Recently the case of FRP flexural reinforcement is actively being used is an excellent weight - rigidity. However, use of FRP bending reinforcement in brittleness material properties of concrete in an actual field application causes destruction of detachment and attachment is being considered as a major cause of destruction. For hybrid laminating plates, tensile and three-point bending tests were performed considering various designs and fabricating methods for hybrid FRP plates. Tensile property of each test specimen was investigated and the research parameter of hybrid laminating plates considered here is the combining ratio of fiber to aluminum contents.

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A Study on the Bearing Capacity of Shallow Foundation according to the Reinforcement Geocell Layer (지오셀 보강 층수에 따른 얕은 기초의 지지력에 관한 연구)

  • Lee, Kyong-Cheon;Baek, Young-Sik;Park, Young-Hun;Kim, Nag-Young
    • Journal of the Korean GEO-environmental Society
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    • v.4 no.4
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    • pp.85-96
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    • 2003
  • The Geocell system is the advanced system of Geo-grids, and is one of geosynthetics used for earth reinforcement of weak soil. It is the way to increase earth strength and bearing capacity by using three dimension type of geo-composite. This paper analyzed the bearing capacity mechanism of Geocell system for earth reinforcement. Plate loading tests under the model laboratory condition were performed, and the increase of bearing capacity and the decrease of settlement with shallow foundation were evaluated.

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A Study on the Standardized Finite Element Models for Carbody Structures of Railway Vehicle Made of Sandwich Composites (샌드위치 복합재 적용 철도차량 차체 구조물의 표준유한요소모델 제시 연구)

  • Jang, Hyung-Jin;Shin, Kwang-Bok;Ko, Hee-Young;Ko, Tae-Hwan
    • Journal of the Korean Society for Railway
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    • v.13 no.4
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    • pp.382-388
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    • 2010
  • This paper describes the standardized finite element model for carbody structures of railway vehicle made of sandwich composites. Recently, sandwich composites were widely used to railway vehicle due to the improvement of energy efficiency, high specific stiffness and strength, weight reduction and space saving in korea. Therefore, structural integrity should be verified using finite element analysis prior to the manufacture of composite railway vehicle. The standardized finite element model for composite carbody structures was introduced through comparing the results of real structural test under vertical, compressive, twisting load and natural frequency test of various railway vehicles in this study. The results show that the quadratic shell element is suitable to model the reinforced metal frame used to improve the flexural stiffness of sandwich panel compared to beam element, and layered shell and solid element are recommended to model the skin and honeycomb core of sandwich panel compared to sandwich shell element. Also, the proposed standard finite element model has the merit of being applied to crashworthiness problem without modifications of finite element model.

Mechanical Characteristics of 3-dimensional Woven Composite Stiffened Panel (3차원으로 직조된 복합재 보강 패널의 기계적 특성 연구)

  • Jeong, Jae-Hyeong;Hong, So-Mang;Byun, Joon-Hyung;Nam, Young-Woo;Kweon, Jin-Hwe
    • Composites Research
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    • v.35 no.4
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    • pp.269-276
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    • 2022
  • In this paper, a composite stiffened panel was fabricated using a three-dimensional weaving method that can reduce the risk of delamination, and mechanical properties such as buckling load and natural frequency were investigated. The preform of the stringer and skin of the stiffened panel were fabricated in one piece using T800 grade carbon fiber and then, resin (EP2400) was injected into the preform. The compression test and natural frequency measurement were performed for the stiffened panel, and the results were compared with the finite element analyses. In order to compare the performance of 3D weaving structures, the stiffened panels with the same configuration were fabricated using UD and 2D plain weave (fabric) prepregs. Compared to the tested buckling load of the 3D woven panel, the buckling loads of the stiffened panels of UD prepreg and 2D plain weave exhibited +20% and -3% differences, respectively. From this study, it was confirmed that the buckling load of the stiffened panel manufactured by 3D weaving method was lower than that of the UD prepreg panel, but showed a slightly higher value than that of the 2D plain weave panel.