• Fashion & Textile Research Journal
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• v.14 no.4
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• pp.629-634
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• 2012

Knitted fabric using acrylic/wool blended yarn (A/W) is increasingly used in the knit industry; subsequently, research on knitted fabric using A/W has increased. This study presents an scientific database from evaluating physical properties of $1{\times}1$ rib stitch using A/W. In this study,$1{\times}1$ rib stitch using A/W were made at various knitting tensions (dial no. 2-6) and the number (4-6) of ply yarn. The physical properties of $1{\times}1$ rib stitch using A/W were measured and analyzed. The density was in the range 5.5-6.4 wales/cm and 4.0-5.6 courses/cm, respectively. The density increased when less plying yarns and more knitting tension were added during knitting. The thickness was in the range of 1.592-2.362 mm and the tensile strength was in the range 32.75-53.63 Kgf/mm. The burst strength was in the range 107.8-139.2 $N/cm^2$. Thickness, tensile strength, and burst strength increased as the number of ply yarn and the knitting tension increased. The elongation and the recovery extension rate were in the range 102.29-112.13% and 96.4-97.7%, respectively. The heat retention rate was in the range 59.3-65.1%. There was no difference of the elongation and the recovery extension rate and the heat retention rate by the knitting tension and the number of the ply yarn. The permeability was in the range 170.5-396.3 $cm^3/cm^2/sec$. Air permeability decreased as the number of ply yarn and the knitting tension increased. The pilling properties were excellent for all $1{\times}1$ rib stitches.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.4
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• pp.461-466
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• 2013

Advanced fiber-reinforced laminated composites are widely used in various fields of engineering to reduce weight. The material property of each ply is well known; specifically, it is known that ply is less reliable than metallic materials and very sensitive to the loading direction. Therefore, it is important to consider this uncertainty in the design of laminated composites. In this study, reliability analysis is conducted using COMSOL and MATLAB interactions for a laminated composite plate for the case in which the tip deflection is the design requirement and the material property is a random variable. Furthermore, the efficiency and accuracy of the approximation method is identified, and a probabilistic sensitivity analysis is conducted. As a result, we can prove the applicability of the advanced design method for the stabilizer of an underwater vehicle.

• Steel and Composite Structures
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• v.21 no.2
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• pp.395-409
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• 2016

Nonlinear vibration characteristics of composite laminated trapezoidal plates are studied. The geometric nonlinearity of the plate based on the von Karman's large deformation theory is considered, and the finite element method (FEM) is proposed for the present nonlinear modeling. Hamilton's principle is used to establish the equation of motion of every element, and through assembling entire elements of the trapezoidal plate, the equation of motion of the composite laminated trapezoidal plate is established. The nonlinear static property and nonlinear vibration frequency ratios of the composite laminated rectangular plate are analyzed to verify the validity and correctness of the present methodology by comparing with the results published in the open literatures. Moreover, the effects of the ply angle and the length-high ratio on the nonlinear vibration frequency ratios of the composite laminated trapezoidal plates are discussed, and the frequency-response curves are analyzed for the different ply angles and harmonic excitation forces.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2004.10a
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• pp.232-235
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• 2004

This is the preliminary study to develop composite window frame of commercial aircraft using VaRTM process. For two candidate carbon fabric(triaxial fabric, sleeving braider dry carbon fiber), specimens were fabricated using VaRTM process ,and then the physical & mechanical tests were performed to gain material property according to ASTM. FEM analysis for each candidate carbon fabric were performed to find the minimum ply number and weight for composite window frame. In this study Tsai-Wu strength failure criteria was utilized to evaluate the safety of structure.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.8
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• pp.1261-1268
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• 2001

Effective material properties of active fiber composites with interdigitated electrodes are derived as a function of the fiber volume fraction. For the purpose of applying the rule of mixture, three unit cell models are introduced; each for the deformation and stress continuities in the out of plane and in-plane directions, and the continuity of the electrical displacement in the longitudinal direction. Derived effective material properties are compared with the results by the finite element method; good agreements are observed between them. As an application, the electromechanical behavior of the angle ply laminates with the active fiber layers bonded on the top and bottom surfaces are investigated; the angle of piezoelectric fiber to maximize the twisting curvature is obtained using the present model.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.1
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• pp.73-80
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• 2008

Experimental study has been performed in order to construct the standard test methods and appraisal criteria by investigating the influence of specimen types(property, width, layers) and loading rate on the tensile characteristics of FRP used in strengthening RC structures. The FRP composite tested in this study are the unidirectional CFRP sheet/strip and the bidirectional GFRP sheet. Test variables consist of the various width ranging from 10mm to 25mm and number of CFRP sheets plied up to 5 layers. Test results indicated that maximum tensile strength and minimum coefficient of variation are recorded at each different width according to the fiber types and weaving directions. Also, the average tensile strengths of CFRP sheets are decreased as the number of layer of CFRP sheet are increased.

• The KSFM Journal of Fluid Machinery
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• v.15 no.4
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• pp.55-60
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• 2012

The purpose of this study is to investigate the buckling load of filament-wound composite towers for large scale wind-turbine using finite element method(FEM). To define material properties, we used both the effective property method and the stacking properties method. The effective properties method is to assume that composite consists of one ply. The stacking properties method is to assume that composite consists of some stacked plies. First, linear buckling analysis of the tower, filament-wounded with angles of [${\pm}30$] was carried out by two methods for composite material properties, the stacking method and the effective method. and FE analysis was performed for the composite towers according to filament winding angles of [${\pm}30$], [${\pm}45$], [${\pm}60$]. FE analysis results using the stacking properties of the composite were in good agreement with the results by the effective properties. The difference between FEM results by material properties methods was approximately 0~2.3% in buckling Analysis and approximately 0~0.6% in modal analysis. And above the angle of [${\pm}60$], there was a little change of buckling load.

• Journal of Ocean Engineering and Technology
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• v.25 no.2
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• pp.73-78
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• 2011

The purpose of this study was to investigate the natural frequency of filament-wound composite towers for large scale wind-turbines using the finite element method (FEM). To define the material properties, we used both the effective property method and the stacking properties method. The effective properties method assumes that a composite consists of one ply. The stacking properties method assumes that a composite consists of several stacked plies. First, a modal analysis of the tower, filament-wound with angles of $[{\pm}30]$, was carried out using the two methods for composite material properties, the stacking method and effective method. Then, an FE analysis was performed for composite towers using filament winding angles of $[{\pm}30]$, $[{\pm}45]$, and $[{\pm}60]$. The FE analysis results using the stacking properties of the composite were in good agreement with the results from the effective properties method. The difference between the FEM and material properties methods was approximately 0~0.6%

• Journal of Ocean Engineering and Technology
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• v.25 no.2
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• pp.79-84
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• 2011

The purpose of this study was to investigate the buckling load of filament-wound composite towers for large scale wind-turbines using the finite element method (FEM). To define the material properties, we used both the effective property method and stacking properties method. The effective properties method assumes that a composite consists of one ply. The stacking properties method assumes that a composite consists of several stacked plies. First, a linear buckling analysis of the tower, filament-wound with angles of $[{\pm}60]$, was carried out using the two methods for composite material properties: the stacking method and effective method. An FE analysis was also performed for the composite towers using the filament winding angles of $[{\pm}30]$, $[{\pm}45]$, and $[{\pm}60]$. The FE analysis results using the stacking properties of the composite were in good agreement with the results from the effective properties method. The difference between the FEM results and material properties method was approximately 0~2.3%. Above the angle of $[{\pm}60]$, there was little change in the buckling load.

• Journal of the Microelectronics and Packaging Society
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• v.22 no.3
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• pp.67-72
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• 2015

A study on thermal properties for a single-layer metal and a 2-ply metal (clad metals) was investigated for the application of heat sink. For the single-layer metal, a stainless steel (STS) and an aluminum (Al) were selected. Also, a roll bonded clad metal with STS and Al was chosen for the 2-ply metal. The thermal conductivity of the sample was obtained from the thermal diffusivity measured by the light flash analysis (LFA), specific heat and density. Measured thermal property values were compared with the calculated values using the data from the references. For the single-layer metal, measured values for the thermal diffusivity and thermal conductivity were smaller than calculated values. Differences between measured and calculated values were about 6% and 18% for the STS and Al samples, respectively. For the clad metals, however, a large difference (55%) was observed. Here, a relatively small thermal conductivity measured by LFA was due to the existence of a interface between STS and Al in the clad metal. Such a interface reduces the moving velocity of free electrons and phonons in the clad metal. For the development of a high performance heat-issipation module with the multi-layer structure, the control of interface properties which determine thermal properties was confirmed to be important.