• 한국전산구조공학회논문집
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• 제24권1호
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• pp.17-22
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• 2011

본 논문에서는 Tsai-Hill기준을 변형하여 조합하중을 받는 이방성재료의 강도를 정확히 예측할 수 있는 새로운 파손기준을 제안하였다. 이 기준의 유효성은 조합하중을 받고 있는 Kraft 판지에 대한 실험결과와 비교하여 나타내었다. 재료축 방향의 전단응력이 주어진 경우, Tsai-Hill기준은 매우 보수적인 결과를 보여주고 있으나, 본 해석에서 제안한 기준은 실험 결과와 잘 일치하고 있다. 또한 Tan-Cheng기준과 비교하여 강도를 더욱 단순하게 해석할 수 있는 능력을 갖고 있다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1999년도 학회창립 10주년 기념 1999년도 가을 학술발표회 논문집
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• pp.717-720
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• 1999

Recently, the fiber composite materials such as carbon fiber, glass fiber, or aramid, have been frequently used in strengthening reinforced concrete structures. The fiber composite materials typically have orthotropic characteristic and the strength changes significantly acording to the direction of fibers and the method of the lamination. In this study, an algorithm to estimate the stress-strain relationship of the composite materials which have different fiber directions and symmetric or non-symmetric lamination has been developed by using Tsai-Hill and Tsai-Wu failure criteria and progressive laminate failure theory. This algorithm has been implemented to several stress-strain models for the laterally confined concrete compression members such as Mander, Hosotani, and Nakatsuka. The evaluated stress-strain behaviors by the different models are discussed.

• 한국가스학회지
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• 제13권4호
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• pp.15-21
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• 2009

섬유강화 복합재료는 비강성과 비강도등의 우수한 기계적 성질을 나타내므로 구조물의 경량화가 요구되는 여러 산업분야에서 널리 사용되고 있다. 이러한 복합재를 이용한 압력용기는 무게를 경량화함으로써 에너지를 절약할 수 있고 강한 내식성을 가지고 있기 때문에 장기간 사용에 유리하다. 본 연구에서는 유한요소법과 ANSYS 반응표면법을 이용하여 안정성 판단의 기준으로 Von-mises 항복 기준, Tasi-hill이론, 응력비를 만족시킬 수 있는 E-glass/epoxy로 필라멘트 와인딩된 CNG차량복합재 압력용기 적층판의 최적설계 모듈을 개발하였다.

• Journal of the Korean Wood Science and Technology
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• 제37권5호
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• pp.465-473
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• 2009

Three failure theories were studied to evaluate the wood strength variation with grain slope. Maximum stress theory, Tsai-Hill theory and Hankinson formula were presented to hypothesize the failure of wood according to grain slope to loading direction. Red pine and Japanese larch were used as materials to simulate failure strength prediction with grain slope. Calculation of strength results was that the strength of wood drops rapidly between parallel to grain orientation (0 degree) and 15 degree grain orientation. The strength of wood with grain orientation were somewhat different at small grain angles among failure theories, and this tendency was due to tension and compression distinction, and shear accounting in each theories. For the above 45 degree grain orientation, the predicted failure strength of wood with grain variation were very close in each failure theories and were useful in assessing failure strength of wood. The applicable these theories should be considered that the wood has different behavior in tension and compression, and this lead to different strength at small grain angles in each theories. Furthermore, reconsideration is needed to assess the failure strength of wood at small grain angles in Hankinson formula and further studies are necessary to accounting for shear behavior at small grain angles.

• Structural Engineering and Mechanics
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• 제73권6호
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• pp.685-698
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• 2020

The dynamic stability of a functionally graded polymer microbeam reinforced by graphene oxides subjected to a periodic axial force is investigated. The microbeam is assumed to rest on an elastic substrate and is subjected to various immovable boundary restraints. The weight fraction of graphene oxides nanofillers is graded across the beam thickness. The effective Young's modulus of the functionally graded graphene oxides reinforced composite (FG-GORC) was determined using modified Halpin-Tsai model, with the mixture rule used to evaluate the effective Poisson's ratio and the mass density. An improved third order shear deformation theory (TSDT) is used in conjunction with the Chebyshev polynomial-based Ritz method to derive the Mathieu-Hill equations for dynamic stability of the FG-GORC microbeam, in which the scale effect is taken into account based on modified couple stress theory. Then, the Mathieu-Hill equation was solved using Bolotin's method to predict the principle unstable regions of the FG-GORC microbeams. The numerical results show the effects of the small scale, the graphene oxides nanofillers as well as the elastic substrate on the dynamic stability behaviors of the FG-GORC microbeams.

• Journal of Ship and Ocean Technology
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• 제4권2호
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• pp.38-57
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• 2000

This paper deals with reliability analysis of specially orthotropic plates subjected to transverse lateral pressure loads by using Monte Carlo simulation method. The plates are simply supported around their all edges and have a low short span to plate depth ratio with rectangular plate shapes. Various levels of reliability analyses of the plates are performed within the context of First-Ply-Failure(FPF) analysis such as ply-/laminate-level reliability analyse, failure tree analysis and sensitivity analysis of basic design variables to estimated plate reliabilities. In performing all these levels of reliability analyses, the followings are considered within the Monte Carlo simulation method: (1) input parameters to the strengths of the plates such as applied transverse lateral pressure loads, elastic moduli, geometric including plate thickness and ultimate strength values of the plates are treated as basic design variables following a normal probability distribution; (2) the mechanical responses of the plates are calculated by using simplified higher-order shear deformation theory which can predict the mechanical responses of thick laminated plates accurately; and (3) the limit state equations are derived from polynomial failure criteria for composite materials such as maximum stress, maximum strain, Tsai-Hill, Tsai-Wu and Hoffman.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 1999년도 추계학술발표대회 논문집
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• pp.63-67
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• 1999

This paper presents the optimization of CFRP laminated rectangular plates using fuzzy theory. In optimization, thickness of CFRP lamina and fiber angle are taken as design variables, and total thickness of the plates is minimized under Tsai-Hill failure criterion. The uncertainties are entered by introducing fuzzy material strengths and then the objective and constraints are represented by a membership function of their own according to the intersection method. Various design results are presented for the CFRP laminated composites plates.

• Journal of Mechanical Science and Technology
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• 제16권10호
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• pp.1211-1221
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• 2002

A shape optimization of stiffener was conducted to increase buckling load or failure load with stiffened laminated composite panel of I-type under compression loading. Design variables are cap length, web length, and/or thickness under the constraint of volume constancy. The objective function is buckling load and failure load of post-buckling based on Tsai-Hill theory using ABAQUS 5.8 for analysis and Optimizer on Broydon-Fletcher Goldfarb-Sharno Method and Augmented Lagrange Multiplier Method. The effects of relative length of a web and a cap of stiffener on buckling load and failure load of post-buckling were investigated with the results of optimum design.

• Composites Research
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• 제14권3호
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• pp.42-50
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• 2001

본 연구에서는 집중하중을 받는 일방향 보강 섬유 금속 적층판의 손상 개시 모델을 연구하였다. 기존의 복합재료 적층판의 해석에 사용하는 일타 전단변형이론을 수정하여 섬유 금속 적층판의 하중 변위 관계를 구하였고, 유한 요소 해석을 통하여 응력을 계산한 다음 Tsai-Hill failure criterion과 Miser yield criterion을 사용하여 섬유층과 금속판의 파괴 지수를 계산하는 방법으로 섬유 금속 적층판의 손상 개시를 모델링하였다. 단순 인장과 원통형 굽힘 하중에서의 적층 각도에 따른 섬유 금속 적층판의 파괴 지수 분포를 통하여 해석의 타당성을 검증하였으며, 이를 바탕으로 집중하중을 받는 경우 섬유 방향에 따른 파괴 지수를 계산하였다. 계산된 파괴 지수를 손상 개시 하중과 비교하기 위하여 압입 시험을 수행하였다. 압입 시험은 섬유 방향의 영향을 보기 위하여 양단 고정인 경계 조건에서 수행하였다. 손상 개시 하중은 압입 선도의 앞 부분을 Hertz식을 이용하여 회귀 분석한 곡선이 실제 하중 곡선과 달라지는 점으로부터 결정하였다. 다양한 섬유 방향에 따른 압입 시험을 수행하였으며 각각의 손상 개시 하중을 파괴 지수와 비교하였다.

• Structural Engineering and Mechanics
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• 제35권3호
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• pp.335-348
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• 2010

Cutouts are often provided in structural and aircraft components for ventilation, for access, inspection, electric lines and fuel lines or sometimes to lighten the structure. This paper addresses the effects of cutout shape (i.e., circular, square, diamond, elliptical-vertical and elliptical-horizontal) and size on buckling and postbuckling response of quasi-isotropic (i.e., $(+45/-45/0/90)_{2s}$) composite laminate under uni-axial compression. The finite element method is used to carry out the investigation. The formulation is based on first order shear deformation theory and von Karman's assumptions are used to incorporate geometric nonlinearity. The 3-D Tsai-Hill criterion is used to predict the failure of a lamina while the onset of delamination is predicted by the interlaminar failure criterion. It is observed that for the smaller size cutout area there is no significant effect of cutout shape on load-deflection response of the laminate. It is also concluded that the cutout size has substantial influence on the buckling and postbuckling response of the laminate with elliptical-horizontal cutout, while this effect is observed to be the least in case of laminate with elliptical-vertical cutout.