• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2000년도 추계학술발표대회 논문집
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• pp.141-146
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• 2000

It has many variables and factors to design the friction materials for automotive brake pads. In this study, the friction and wear characteristics of automotive blake pads have been studied using 1:l full size dynamo meter. Using conventional manners, it takes a great of time and efforts to know that it affects the each raw materials for friction characteristics. For the purpose of examining the effect of each major raw materials, we used the more convenient Taguchi L9 ($3^4$) orthogonal matrix and 1/5 scale dynamo machine for evaluation of the friction characteristics of composite brake pads.

• Structural Engineering and Mechanics
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• 제3권1호
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• pp.49-60
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• 1995

In the present study, a finite strip method for the vibration and stability analyses of anisotropic laminated composite plates is developed according to the higher-order shear deformation theory. This theory accounts for the parabolic distribution of the transverse shear strains through the thickness of the plate and for zero transverse shear stresses on the plate surfaces. In comparison with the finite strip method based on the first-order shear deformation theory, the present method gives improved results for very thick plates while using approximately the same number of degrees of freedom. It also eliminates the need for shear correction factors in calculating the transverse shear stiffness. A number of numerical examples are presented to show the effect of aspect ratio, length-to-thickness ratio, number of plies, fibre orientation and stacking sequence on the natural frequencies and critical buckling loads of simply supported rectangular cross-ply and arbitrary angle-ply composite laminates.

• Structural Engineering and Mechanics
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• 제82권6호
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• pp.691-699
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• 2022

This paper is devoted to the presentation of a numerical study on vibration behavior of composite panels reinforced by glass fibres and carbon nanotubes (CNTs) subjected to thermal environments. The effect of temperature variation has been included as thermal load acting on in-plane direction of the panel. To model the composite material, a micromechanical model which contains random dispersion of nanotubes and single-direction fibers has been selected. The geometry of the panel has been considered to have a single curveture along its width. Based on the above assumptions, the governing equations have been derived by using thin shell theory capturing the panel curveture and also nonlinear deflections. Finally, the panel dependence on various factors such as the curveture, nanotube amount, fiber volume, fiber direction and temperature variation has been researched.

• Advances in concrete construction
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• 제3권4호
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• pp.295-316
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• 2015

A bridge widening technology using steel-concrete composite system was developed and is presented in this paper. The widened superstructure system consists of a newly built composite steel-concrete girder with concrete deck and steel diaphragms attached to the existing concrete girders. This method has been applied in several bridge widening projects in China, and one of those projects is presented in detail. Due to the higher stiffness-to-weight ratio and the rapid erection of composite girders, this widening method reveals benefits in both mechanical performance and construction. As only a few methods for the design of bridges with different types of girders are recommended in current design codes, a more accurate analytical method of estimating live load distribution on girder bridges was developed. In the analytical model, the effects of span length, girder pacing, diaphragms, concrete decks were considered, as well as the torsional and flexural stiffness of both composite box girders and concrete T girders. The study shows that the AASHTO LRFD specification procedures and the analytical models proposed in this paper closely approximate the live load distribution factors determined by finite element analysis. A parametric study was also conducted using the finite element method to evaluate the potential load carrying capacities of the existing concrete girders after widening.

• 항공우주기술
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• 제6권1호
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• pp.230-236
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• 2007

항공기용 복합재 구조물의 제작에 대한 품질관리는 자재의 입고에서부터 제품의 제작과정에 이르는 모든 단계에서의 검사, 시험 및 모니터링을 포함한다. 이러한 품질관리 활동은 설계의 목적에 적합하게 이루어졌는지 확인하기 위한 것이다. 품질에 영향을 미치는 인자들은 자재, 입고검사, 보관 및 시효관리, 작업환경의 관리, 시험, 검사 및 기록의 관리 등이 있다. 본 연구에서는 항공기 복합재 구조물에서 파괴시험을 통한 공정의 적합성 입증방법과 품질관리방법을 고찰하였으며 이를 바탕으로 복잡한 복합재 구조물에 대한 비파괴검사 방법의 신뢰성을 확보하고 복합재의 설계요구조건을 확인할 수 있는 기법을 제시하였다.

• 복합신소재구조학회 논문집
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• 제6권4호
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• pp.30-37
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• 2015

iFLASH System is new structural floor system which consists of sandwich panels filled with nano-composite. The nano-composite has low specific gravity and high bonding strength with steel plates. The bonding strength is one of important factors for structural performance of iFLASH System and it can further be improved by surface preparation such as blast metal cleaning. However, using none blast steel plates is recommended since surface preparation generates additional fabrication time and cost. In this study, a bonding strength test and bending experiment were conducted to check feasibility of applying none blast steel plates to iFLASH System. Moreover, stress in bonding plane between steel plates and nano-composite was analytically evaluated by finite element method. Consequently, flexural capacity of the specimen was 11% higher than theoretically calibrated value and its flexural behavior was structurally efficient without defect of bonding.

• Macromolecular Research
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• 제11권3호
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• pp.163-171
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• 2003

For the pervaporation of water-ethanol mixtures, new composite membranes having poly(acrylic acid)-poly (butyl methacrylate-co-methyl methacrylate) interpenetrati ng polymer network [PAA-P(BMA-co-MMA) IPN] skin layer supported on porous and crosslinked poly(BMA-co-MMA) were prepared. The morphology of the sub-layer of the composite membrane prepared in the presence of 60 wt% solvent showed cellular structure, on the other hand that of sublayer prepared in the presence of 70 wt% solvent presented very porous interconnected pore structure with macrovoids. Permeation rates of the composite membranes were largely influenced by the morphology of the sublayer. Separation factors increased with the increase of the degree of crosslinking of the PAA network. It was found that permeation rates could be increased by introducing anionic charges on carboxyl groups of the PAA. The permeation rate changes of the PAA-P(BMA-co-MMA) IPN composite membranes according to the feed compositions showed quite similar pattern with the swelling behavior in water-ethanol mixtures.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2000년도 추계학술발표대회 논문집
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• pp.245-248
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• 2000

Modern aircraft composite structures are designed using a damage tolerance philosophy. This design philosophy envisions sufficient strength and structural integrity of the aircraft to sustain major damage and to avoid catastrophic failure. The only reasonable way to treat on the same basis all the conditions and uncertainties participating in the design of damage tolerant composite aircraft structures is to use the probability-based approach. Therefore, the model has been developed to assess the probability of structural failure (POSF) and associated risk taking into account the random mechanical loads, random temperature-humidity conditions, conditions causing damages, as well as structural strength variations due to intrinsic strength scatter, manufacturing defects, operational damages, temperature-humidity conditions. The model enables engineers to establish the relationship between static/residual strength safety margins, production quality control requirements, in-service inspection resolution and criteria, and POSF. This make possible to estimate the cost associated with the mentioned factors and to use this cost as overall criterion. The methodology has been programmed into software.

• 품질경영학회지
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• 제49권1호
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• pp.31-45
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• 2021

Purpose: A noncentral composite design method is to be developed to explore farther region for the first factorial design. A general guideline for sequential experimentation is provided. Methods: (1) A non-overlapping noncentral composite design (NNCD) is developed, in which the second factorial design shares one design point that indicates the best response value in the first factorial design. (2) Four composite designs are compared in terms of the four design evaluation criteria, which are D-, A, G, and I-optimality. (3) A follow-up design strategy is suggested based on the interaction effect, direction of improvement, number of factors. Results: (1) NNCD and model building method are presented, which is useful for exploring farther region from first factorial design block. (2) The performances of the four composite designs are compared. (3) A follow-up design strategy is suggested. Conclusion: (1) NNCD will be useful to explore farther region for the first factorial design. (2) A follow-up design strategy can be beneficial to the experimental practitioners for product and process design and improvement.

• Steel and Composite Structures
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• 제42권2호
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• pp.221-241
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• 2022

Perfobond rib connectors are widely used in composite structures to achieve the composite action between the steel and the concrete, and empirical expressions for their strength and secant stiffness have been obtained by numerical simulations or push-out tests. Since perfobond connections are generally in an elastic state in the service process and the structural analysis are always based on the elastic properties of the members, the secant stiffness is not applicable for the normal structural analysis. However, the tangent stiffness of perfobond connections has not been introduced in previous studies. Moreover, the perfobond connections are bearing tension and shear force simultaneously when the composite beams subjected to torque or local loads, but the current studies fail to arrive at the elastic stiffness considering the combined effects. To resolve these discrepancies, this paper investigates the initial elastic stiffness of perfobond connections under combined forces. The calculation method for the elastic stiffness of perfobond connections is analyzed, and the contributions of the perfobond rib, the perforating rebar and the concrete dowel are investigated. A finite element method was verified with a high value of correlation for the test results. Afterwards, parametric studies are carried out using the reliable finite element analysis to explore the trends of several factors. Empirical equations for predicting the initial elastic stiffness of perfobond connections are proposed by the numerical regression of the data extracted by parametric studies. The equations agree well with finite element analysis and test results, which indicates that the proposed empirical equations reflect a high accuracy for predicting the initial elastic stiffness of perfobond connections.