• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 1999년도 추계학술발표대회 논문집
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• pp.234-238
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• 1999

This study suggests the design of the functionally gradient composite, [0/90/0/core]$_s$ cross-ply laminate, to prevent stress concentration induced from the difference of rigidity between the bone and the artificial hip joint and to reinforce the wear property of the surface and the expectation of their mechanical properties. First, the four-point bending test is done about wet bones and dry bones to know the mechanical properties of the cortical bones. In result, the wet bone shows the viscoelastic behavior and the dry bone shows the elastic behavior. Moreover, we expect the properties of the proposed gradient composites as a function of carbon fiber volume fraction in each layer to apply Halpin-Tsai equation, CLPT(classical laminate plate theory), and Bernoulli beam theory etc. and decide the thickness ratio of each lamina in order to match Young's modulus of the anisotropic cortical bone with the proposed gradient composites.

• EDISON SW 활용 경진대회 논문집
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• 제4회(2015년)
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• pp.285-291
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• 2015

In this paper, a composite material analysis program based on the finite element method(FEM) is used. The purpose of this study was to verify whether the composite material analysis program which developed as part of a project of development of softwares and educational contents for structural vibration and composite material analysis that can calculate how similar the macroscopic mechanical behavior of the composite materials actually. Because composite materials are generally anisotropic, analysis of composite laminate is used for the constitutive equations of orthotropic material. For convenience, the unit is ommited in all calculations. To verify the accuracy of the finite element method based program, the deflection and stress distribution of the simply supported composite material laminated plate subjected to a uniform load distribution is compared with exact solution. Size and properties of the composite material laminate used for analysis are fixed variables, and by changing the number of elements and the total thickness of the laminate is compared with the exact solution to the resulting value, respectively.

• Structural Engineering and Mechanics
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• 제69권3호
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• pp.327-334
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• 2019

The purpose of this paper is to investigate the hygrothermal effects on the behavior of reinforced-concrete beams strengthened by bonded composite laminate plates (${\theta}n/90m)s$. This work is based on a simple theoretical model to estimate the interfacial stresses developed between the concrete beam and the composite with taking into account the hygrothermal effect. Fibre orientation angle effects of number of $90^{\circ}$ layers and effects of plate thickness and length on the distributions of interfacial stress in the concrete beams reinforced with composite plates have also been studied.

• 오토저널
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• 제11권1호
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• pp.44-50
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• 1989

본 논문에서는 모우드 해석법(Modal Analysis Method)을 이용하여 종래 재료에 비해 우 수한 기계적 성질을 갖는 복합재료에 대하여 동특성을 규명하고자 하였다. 재료로는 알루미늄 판(AL PLATE)과 탄소섬유강화 복합적층판(CFRP)을 비교하였으며, 그 결과 전체적인 진동레 벨이 AL PLATE 보다 CFRP PLATE가 낮았고 섬유방향이 고정단고 직각인 경우보다 평행인 경우가 낮음을 알았다. 또한 AL PLATE와 유사한 진동형을 나타내는 CFRP PLATE의 고유 진동모우드가 저주파수쪽으로 이동함을 알 수 있었다.

• Composites Research
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• 제29권5호
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• pp.231-235
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• 2016

본 연구에서는 동일한 구조의 모자형 보강재를 이용하여 일체형 동시접착 구조의 보강패널시편을 제작하였다. 일반적인 동시접착 보강패널 시편과 탄소에폭시 복합재를 이용하여 제작된 카울플레이트(Caul Plate)를 적용한 동시접착 보강패널 시편의 2가지 형태 시편을 제작하였으며 일반 동시접착 보강패널 시편에서는 패널 상에서 보강재가 적용되지 않은 부위가 적용된 부위보다 더 두꺼운 패널 두께를 가지고 그 연결부위에는 0.61 mm 높이 및 3.29 mm 길이의 플라이웨이브 현상이 나타났다. 카울플레이트가 적용된 보강패널 시편에서는 보다 균일한 압력 전달로 인하여 0.22 mm 높이와 1.37 mm 길이의 완화된 웨이브 현상을 보이면서 약 50% 이상 개선된 결과를 얻을 수 있었다.

• Journal of Mechanical Science and Technology
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• 제19권4호
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• pp.947-957
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• 2005

In this study a simple model is developed that predicts impact damage in a composite laminate avoiding the need of the time-consuming dynamic finite element method (FEM). The analytical model uses a non-linear approximation method (Rayleigh-Ritz) and the large deflection plate theory to predict the number of failed plies and damage area in a quasi-isotropic composite circular plate (axisymmetric problem) due to a point impact load at its centre. It is assumed that the deformation due to a static transverse load is similar to that oc curred in a low velocity impact. It is found that the model, despite its simplicity, is in good agreement with FEM predictions and experimental data for the deflection of the composite plate and gives a good estimate of the number of failed plies due to fibre breakage. The predicted damage zone could be used with a fracture mechanics model developed by the second investigator and co-workers to calculate the compression after impact strength of such laminates. This approach could save significant running time when compared to FEM solutions.

• Advances in materials Research
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• 제11권2호
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• pp.91-109
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• 2022

This paper presents a closed-form higher-order analysis of interfacial shear stresses in RC continuous beams strengthened with bonded prestressed laminates. For retrofitting reinforced concrete continuous beams is to bond fiber reinforced prestressed composite plates to their tensile faces. An important failure mode of such plated beams is the debonding of the composite plates from the concrete due to high level of stress concentration in the adhesive at the ends of the composite plate. The model is based on equilibrium and deformations compatibility requirements in and all parts of the strengthened beam, where both the shear and normal stresses are assumed to be invariant across the adhesive layer thickness. In the present theoretical analysis, the adherend shear deformations are taken into account by assuming a parabolic shear stress through the thickness of both the RC continuous beams strengthened with bonded prestressed laminates. The theoretical predictions are compared with other existing solutions. A parametric study has been conducted to investigate the sensitivity of interface behavior to parameters such as laminate stiffness and the thickness of the laminate where all were found to have a marked effect on the magnitude of maximum shear and normal stress in the composite member.

• International Journal of Aeronautical and Space Sciences
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• 제11권3호
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• pp.221-226
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• 2010

The failure of a Kevlar29/Phenolic composite plate under high-velocity impact from an fragment simulation projectile was investigated using the nonlinear explicit finite element code, LS-DYNA. The composite laminate and the impactor were idealized by solid elements, and the interface between the laminas was modeled as a tiebreak type in LS-DYNA. The interaction between the impactor and laminate was simulated using a surface-to-surface eroding contact algorithm. When the stress level meets the given failure criteria, the layer in the element is eroded. Numerical results were verified through existing test results and showed good agreement.

• Composites Research
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• 제33권3호
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• pp.115-124
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• 2020

적층복합재료, 특히 탄소섬유 복합재료는 금속에 비해 가벼우며 상대적으로 비강도 및 비강성이 뛰어나기 때문에 항공 우주 산업 및 자동차 산업 등과같이 광범위한 분야에서 사용되고 있다. 그러나, 적층 복합재료는 섬유의 배열이 모두 면내방향으로 배열되어있기 때문에 박리가 발생한다는 큰 단점이 있으며, 이는 적층복합재료의 응용분야를 제한한다. 본 연구에서는 먼저 π-빔과 평판이 결합된 형태의 적층복합재료 T-빔을 개발하고, 구조해석 및 기계적 물성평가를 통하여 설계변수를 최적화하였다. 이후 적층복합재료 T-빔의 설계변수를 3D 직조 프리폼에 동일하게 적용하여 T-빔을 개발하였으며, 적층구조에 비하여 향상된 기계적 강도를 달성할 수 있었다. 이러한 연구결과는 강도향상을 필요로 하는 기존의 적층복합재료 구조물에 적용 가능할 것으로 기대된다.

• Steel and Composite Structures
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• 제29권1호
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• pp.39-51
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• 2018

Position of a circular or elliptical cutout within an orthotropic plate has great influence on its buckling behavior. This paper aims at finding the optimal position (both location and orientation) of a single circular/elliptical cutout, within an orthotropic rectangular plate, that maximizes the critical buckling load. We consider linear buckling of simply supported orthotropic plates under uniaxial edge loads. To obtain the optimal positions of the cutouts, we have employed a MATLAB optimization routine coupled with buckling computation in ANSYS. Our results show that the position of the cutout that maximizes the buckling load has great dependence on the material properties, laminate configurations, and the geometrical parameters of the plate. These optimal results, for a number of plate geometries and cutout sizes, are reported in this paper. These results will be useful in the design of perforated orthotropic plates against buckling failure.