• 대한기계학회논문집
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• 제15권3호
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• pp.713-722
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• 1991

본 연구에서는 graphite/epoxy와 glass/epoxy 그리고 graphite/epoxy와 kevl- ar/epoxy의 혼합적층된 복합재료 평판의 저속충격에 대한 응답을 유한요소 모델을 사 용하여 수치해석 한후, 각각의 단일적층판들의 결과와 비교하였으며, 이때의 접촉력 관계식은 Yang과 Sun이 제안한 수정된 접촉법칙을 이용하였다. 또한, 수치해석 결과 에서의 충격자의 속도변화로써 혼합적창판 배열에 따른 에너지 흡수율을 계산하였고, 이를 충격특성이 취약한 graphite/epoxy 단일 적층판의 결과와 비교 고찰하였다.

• Steel and Composite Structures
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• 제34권1호
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• pp.91-105
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• 2020

Steel-concrete composite beam with profiled steel sheet has gained its popularity in the last two decades. Due to the ageing of these structures, retrofitting in terms of flexural strength is necessary to ensure that the aged structures can carry the increased traffic load throughout their design life. The steel ribs, which presented in the profiled steel deck, limit the use of shear connectors. This leads to a poor degree of composite action between the concrete slab and steel beam compared to the solid slab situation. As a result, the shear connectors that connects the slab and beam will be subjected to higher shear stress which may also require strengthening to increase the load carrying capacity of an existing composite structure. While most of the available studies focus on the strengthening of longitudinal shear and flexural strength separately, the present work investigates the effect of both flexural and longitudinal shear strengthening of steel-concrete composite beam with composite slab in terms of failure modes, ultimate load carrying capacity, ductility, end-slip, strain profile and interface differential strain. The flexural strengthening was conducted using carbon fibre reinforced polymer (CFRP) or steel plate on the soffit of the steel I-beam, while longitudinal shear capacity was enhanced using post-installed high strength bolts. Moreover, a combination of both the longitudinal shear and flexural strengthening techniques was also implemented (hybrid strengthening). It is concluded that hybrid strengthening improved the ultimate load carrying capacity and reduce slip and interface differential strain that lead to improved composite action. However, hybrid strengthening resulted in brittle failure mode that decreased ductility of the beam.

• Structural Engineering and Mechanics
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• 제78권3호
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• pp.319-332
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• 2021

The wood-concrete composite is an interesting solution in the field of Civil Engineering to create high performance bending elements for bridges, as well as in the building construction for the design of wood concrete floor systems. The authors of this paper has been working for the past few years on the development of the bonding process as applied to wood-concrete composite structures. Contrary to conventional joining connectors, this assembling technique does ensure an almost perfect connection between wood and concrete. This paper presents a careful theoretical investigation into interfacial stresses at the level of the two interfaces in composite wooden beam- reinforced concrete slab strengthened by external bonding of prestressed composite plate under a uniformly distributed load. The model is based on equilibrium and deformations compatibility requirements in all parts of the strengthened composite beam, i.e., the wooden beam, RC slab, the CFRP plate and the adhesive layer. The theoretical predictions are compared with other existing solutions. This research is helpful for the understanding on mechanical behaviour of the interface and design of the CFRP- wooden-concrete hybrid structures.

• Steel and Composite Structures
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• 제37권6호
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• pp.649-662
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• 2020

Although several types of rigid shear connectors have been developed particularly to increase load-carrying capacity, application is limited due to the complicated details of such connection. In this study, push-out tests were performed for specimens with hybrid shear connectors using headed studs and shear plates to identify the effects of each parameter on the structural performance of such shear connection. The test parameters included steel ratios of headed stud to shear plate, connection length, and embedded depth of shear plates. The peak strength and residual strength were estimated using various shear transfer mechanisms such as stud shear, concrete bearing, and shear friction. The hybrid shear connectors using shear plates and headed studs showed large load-carrying capacity and deformation capacity. The peak strength was predicted by the concrete bearing strength of the shear plates. The residual strength was sufficiently predicted by the stud shear strength of headed studs or by shear friction strength of dowel reinforcing bars. Further, the finite element analysis was performed to verify the shear transfer mechanism of the connection with hybrid shear connector.

• Steel and Composite Structures
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• 제13권1호
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• pp.91-107
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• 2012

In this research, mechanical buckling of hybrid functionally graded plates is considered using a new four variable refined plate theory. Unlike any other theory, the number of unknown functions involved is only four, as against five in case of other shear deformation theories. The theory presented is variationally consistent, does not require shear correction factor, and gives rise to transverse shear stress variation such that the transverse shear stresses vary parabolically across the thickness satisfying shear stress free surface conditions. The plate properties are assumed to be varied through the thickness following a simple power law distribution in terms of volume fraction of material constituents. Governing equations are derived from the principle of minimum total potential energy. The closed-form solution of a simply supported rectangular plate subjected to in-plane loading has been obtained by using the Navier method. The effectiveness of the theories is brought out through illustrative examples.

• 대한기계학회논문집
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• 제16권12호
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• pp.2306-2314
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• 1992

본 연구에서는 Lagrangian 방정식을 이용해 알루미늄, CFRP, GFRP, BFRP 등으 로 혼합적층된 cross-ply 사각판에 대해 굽힘-신장연성을 고려하여 Runge-Kutta Gill 법을 적용하여 수치적으로 비선형진동해석을 수행하였다.그리고 여러가지 적층방법 에 따라 비선형 진동에 어떠한 영향이 미치는가를 검토하였으며, 형상비(a/b), 모우드 의 변화 그리고 탄성계수비에 따른 비선형진동 거동을 규명하였다. 한편, 기본진동 수에 대해서는 상용 유한요소프로그램인 ABAQUS의 결과와 비교하였으며, 단일 적층된 판의 비선형진동거동에 대해서는 Singh의 결과와 비교 검토하였다.

• Steel and Composite Structures
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• 제23권6호
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• pp.737-746
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• 2017

In this paper the influence of aspect ratio, height ratio and material angle on static and free vibration behaviour of orthotropic elliptic paraboloid shells is studied by using a four-node hybrid stress finite element. The formulation of the element is based on Hellinger-Reissner variational principle. The element is developed by combining a hybrid plane stress element and a hybrid plate element. A parametric study is carried out for static and free vibration response of orthotropic elliptic paraboloid shells with respect to displacements, internal forces, fundamental frequencies and mode shapes by varying the aspect and height ratios, and material angle.

• 한국철도학회논문집
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• 제15권2호
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• pp.97-103
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• 2012

허니컴 샌드위치 복합재는 가볍고 강하며, 제작하기가 편리한 장점이 있어 철도차량 차체에 적용되기 시작하였다. 보통 중량감소량은 27%에 달하나, 재료비가 알루미늄 압출재에 비해 높기 때문에 차체에 널리 적용되지 못하였다. 본 논문에서는 두 가지 경량화 재질에 대하여 제작 과정을 고찰하고 원가를 분류하여 과거 자료를 기초로한 경제성을 분석하였다. 복합재 차체의 재료비 상승분을 제작의 용이성으로 상쇄할 수 있으며, 대량생산에 따른 장비비를 저감하면 알루미늄 차체에 비해 경쟁력을 가질 수 있음을 알 수 있었다. 지하철 노선의 통계자료를 참고로 하여 중량 감소에 따른 운행 에너지 감소량도 제시하였다.

• 대한기계학회논문집
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• 제19권4호
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• pp.1013-1022
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• 1995

A hybrid composite (APAL;Aramid Patched ALuminum alloy, CPAL;Carbon Patched ALluminum alloy), consisting of a Al 2024-T3 aluminum alloy plate sandwiched between two aramid/epoxy and carbon/epoxy laminate, was developed. Fatigue crack growth behavior was examined at stress ratios of R=0.2, 0.5. The APAL and CPAL showed superior fatigue crack growth resistance, which may be attributed to the crack bridging effect imposed by the intact fibers in the crack wake.

• 산업기술연구
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• 제17권
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• pp.199-204
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• 1997

In this paper, the result of application of vibration method to the orthotropic plates with free edges supported on elastic foundation and with a pair of opposite edges under axial forces is presented. Such plates represent the concrete highway slab and hybrid composite pavement of bridges. The reinforced concrete slab can be assumed as a special orthotropic plate, as a close approximation. The highway slab is supported on elastic foundation, with free boundaries. Sometimes, the pair of edges perpendicular to the traffic direction may be subject to the axial forces. The plate is subject to the concentrated load/loads, in the form of traffic loads, or the test equipments. Finite difference method is used to obtain the deflection influence surfaces needed for vibration analysis. The influence of the modulus of the foundation, the aspect ratio of the plate, and the magnitudes of the axial forces and the concentrated attached mass on the plate, under the natural frequency is thoroughly studied.