• Transactions of Materials Processing
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• v.22 no.3
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• pp.150-157
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• 2013

Fiber metal laminates (FMLs) are layered materials comprised of thin metal sheets and fiber reinforced plastic (FRP). This paper presents the numerical study of the formability enhancement of FMLs composed of an aluminum alloy and self-reinforced polypropylene (SRPP) composite. In this study, a numerical simulation based on finite element (FE) modeling is proposed to evaluate the formability of FMLs using ABAQUS/Explicit. The FE model, which included a single layer of solid and shell elements to model the blank, used discrete layers of the solid element with a contact model and shell elements with a friction based model for the aluminum alloy-composite interface conditions. This method allowed the description of each layer of FMLs and was able to simulate the interaction between the layers. It is noted through this research that the proposed numerical simulation described properly the formability enhancement of the FMLs and the simulation results showed good agreement with experimental results.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2017.05a
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• pp.67-68
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• 2017

This paper discusses the application of civil structure use reinforcing fiber mixed with concrete to be used as protection layer of waterproofing material and root resistant layer installed in below-grade parking lot upper slab of residential building. A performance evaluation under the prescribed method outlined in KS F 4938 was used for this new material. The testing results showed that the fiber reinforcement can be used to strengthen the protection for the waterproofing material. Also, plants that were planted in June 2016 have not yet penetrated the specimens used for root resistance testing. The domestic root resistance performance testing usually covers the period of 2 years, thus further observation to make any conclusion about the root resistance property is required.

• Textile Coloration and Finishing
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• v.22 no.1
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• pp.77-82
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• 2010

Highly conductive yarn was successfully obtained using electroless nickel plating method with palladium activation. In the presence of palladium seed on surface of fibers as a catalyst, continuos nickel layer produced on surface of fibers by reducing $Ni${2+}$ ion in the electroless plating bath to $Ni^0$. It was found that the Pd-activation using $SnCl_2$ and $PdCl_2$ to deposit palladium seeds on the surface of fibers plays a key role in the subsequent electroless plating of nickel. It also found that electroless nickel plating on the fibers can induce the nickel-plated $ELEX^{(R)}$ fibers to improve the electrical conductivity of the fibers. The thickness of nickel coating layer on the Pd-activated $ELEX^{(R)}$ fibers and specific conductivity of the fiber were increased through electroless plating time. The temperature of nickel plating bath was very effective to enhance the nickel deposition rate.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.40 no.4
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• pp.59-65
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• 2008

Electrochemical properties of pulp fiber could be modified by LbL(Layer-by-Layer) multilayering. Salt concentration and pH affect the conformation and ionization degree of polyelectrolyte. In this study, therefore, we intended to evaluate the effect of pH and salt concentration in polyelectrolyte multilayering on the electrochemical properties of pulp fiber. The pH of the stock was varied to 4, 7, and 10. Salt concentration was controlled at 0.001, 0.003, and 0.005 M of NaCl. Higher zeta potential was obtained when pulp fibers were multilayered at the condition of higher pH and higher salt concentration. The final zeta potential of pulp fiber after multilayering was dependent on the adsorption ratio of polyelectrolyte and the initial zeta potential of fibers.

• Proceedings of the Korean Fiber Society Conference
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• 2003.04a
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• pp.107-110
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• 2003

본 연구에서는 3차원 브레이딩 기계를 이용하여 제작된 6 layer의 3차원 원형 형태로 브레이드된 유리 섬유 강화 복합재료의 프리프레그를 이용하여 에폭시 수지를 모체로 하는 RTM(Resin Transfer Molding) 공정을 통해 직교 이방성 복합재료를 제작하였다. 또한 탄성한계 내에서의 구성방정식을 얻기 위해 unit cell 모델링을 통해 복합재료의 기하를 모사하고 method of cells 이론과 homogenization technique를 이용하여 복합재료의 구성방정식을 나타내는 수치해석 코드를 개발하였다. (중략)

• Earthquakes and Structures
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• v.4 no.1
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• pp.1-10
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• 2013

The present investigation deals with the analysis of wave motion in the layer of an anisotropic, initially stressed, fiber reinforced thermoelastic medium. Secular equations for symmetric and skew-symmetric modes of wave propagation in completely separate terms are derived. The amplitudes of displacements and temperature distribution were also obtained. Finally, the numerical solution was carried out for Cobalt and the dispersion curves, amplitudes of displacements and temperature distribution for symmetric and skew-symmetric wave modes are presented to evince the effect of anisotropy. Some particular cases are also deduced.

• Journal of the Korean Geotechnical Society
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• v.21 no.5
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• pp.225-230
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• 2005

At present, there are several problems related with sand mat which is used as a way to accelerate consolidation settlement, to act like an underground drainage layer and to increase trafficability simultaneously. First of all, the unbalance of the demand and supply of sand is one of the biggest problems, which causes not only price rise but also delay of the term of the total construction work. Secondly, the damage of ecosystem and scenery is triggered by thoughtless sand dredging or mining. So, the need that sand mat should be replaced with a new environmentally friendly material has been increased. Fiber mat may be one of the proper materials that suits the need. Therefore, we intended to compare the drainage properties of sand mat with those of fiber mat by experimental model tests. On the basis of the test results, fiber mat took shorter period of consolidation than sand mat and the amount of settlement in the farmer showed a little bit bigger than in the latter. As a conclusion, the substitutability of sand mat with fiber mat could be placed highly in view of drainage efficiency. Furthermore, when fiber mat is used, it has an advantage that spoiled soil of the construction site or nearby site can be used for the purpose of increasing trafficability in addition to a role of drainage layer.

• Journal of the Korea institute for structural maintenance and inspection
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• v.7 no.3
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• pp.157-165
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• 2003

The paper deals with the rupture strain estimation of fiber sheets. The experimental study involved tensile testing of 120 fiber sheet specimens and bending testing of 72 concrete beams strengthened with various types of fiber sheets(carbon, glass, and aramid fiber). Concrete beams have 3 types of reinforcement ratios. Rupture strains of fiber sheet specimens are determined by tensile tests to be a little less than the tensile failure strain by the catalog, independently on the number of fiber sheet layers. It is shown that the rupture strain of fiber sheet bonded to reinforced concrete beam is not constant, but decreases as the fiber sheet layer increases. Based on these results, the rupture fiber sheet strain is estimated.

• Journal of Korean Neurosurgical Society
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• v.29 no.5
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• pp.599-603
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• 2000

Objectives : In lumbar spine surgery it is observed that the ligamentum flavum(LF) is bilayered, and the inner layers can be left in situ to prevent peridural adhesion in open lumbar disc surgeries. The purposes of this study are to investigate ultrastructural differences between the inner and outer layer of lumbar LF by electron microscopic examination, and to see whether these differences are, if present, more prominent in chronic degenerative lumbar spinal disorders as compared with acute lumbar disc diseases. Methods : Biopsy specimens of LF were obtained from nine patients undergoing lumbar spine surgery, five of them for degenerative spinal stenosis and four for acute disc herniation. During the surgery the outer layers of LF were carefully dissected from the inner layer, and four pieces($1{\times}1{\times}1-mm$) of biopsy samples were made from each layer. These were examined with electron microscope for the morphologies and the contents of the elastic and the collagen fibers. Results : The outer layer of LF showed elastic fiber degeneration as evidenced and decreased fiber content, while the inner layer was relatively preserved in both cases of degenerative spinal stenosis and acute disc herniation. The ultrastructural changes of the layers were more evident in the outer layer. Conclusion : With these observations the authors believe that the LF degeneration may occur mainly in the outer layer, and that this fact may aid in making the rationale for using the inner layer as physiologic barrier to prevent peridural adhesion in open lumbar disc surgeries.

• Journal of Mechanical Science and Technology
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• v.17 no.3
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• pp.343-349
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• 2003

The fuselage-wing intersection suffers from the cyclic bending moment of variable amplitude. Therefore, the influence of cyclic bending moment on the delamination and the fatigue crack propagation behavior in AFRP/Al laminate of fuselage-wing was investigated in this study. The cyclic bending moment fatigue test in AFRP/Al laminate was performed with five levels of bending moment. The shape and size of the delamination Lone formed along the fatigue crack between aluminum sheet and aramid fiber-adhesive layer were measured by an ultrasonic C-scan. The relationships between da/dN and ΔK, between the cyclic bending moment and the delamination zone size, and between the fiber bridging behavior and the delamination zone were studied. As results, fiber failures were not observed in the delamination zone in this study, the fiber bridging modification factor increases and the fatigue crack growth rate decrease and the shape of delamination zone is semi-elliptic with the contour decreasing non-linearly toward the crack tip.