• 한국정밀공학회지
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• 제29권12호
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• pp.1296-1303
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• 2012

There is a certain limit to reproduce phenomena between the real vehicle and road, since the existing methods to verify durability of the wheel are mostly uni-axial tests. And the change of durability of the wheel can't be predicted since these tests don't consider the camber angle and lateral force as important factors. In this paper, the FE models of the wheel-tire and drum are created. Then, the vertical and lateral loads are applied to wheel-tire assembly and the camber angle is applied by inclining the wheel-tire assembly to the drum. Based on the analysis result, the crack position is predicted to be created in the body of the wheel. The variation of the stress according to the camber angle is verified and the maximum spot of the stress changes continually.

• Computational Structural Engineering : An International Journal
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• 제1권2호
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• pp.117-130
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• 2001

Investigations of low-rice unbounded reinforced concrete shear walls with or without openings are performed with comparison of analytical and experimental results. Theoretical analysis is based on nonlinear finite element algorithm, which incorporates concrete failure criterion and nonlinear constitutive relationships. Studios focus on the effects of height-to-length ratio of shear walls, opening ratio, horizontal and vertical reinforcement radios, and diagonal reinforcement. Analytical solutions conform well with experimental results. Equations for cracking, yielding and ultimate loads with corresponding lateral displacements are derived by regression using analytical results and experimental data. Also, failure modes of low-rise unbounded shear walls are theoretically investigated. An explanation of change in failure mode is ascertained by comparing analytical results and ACI code equations. Shear-flexural failure can be obtained with additional flexural reinforcement to increase a wall's capacity. This concept leads to a design method of reducing flexural reinforcement in low-rise bounded solid shear wall's. Avoidance of shear failure as well as less reinforcement congestion leer these walls is expected.

• 자동차안전학회지
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• 제8권1호
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• pp.26-30
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• 2016

The steel road wheel on ventilation holes was cracked in the vehicle durability test. But the component durability test by uni-axial, CFT(Cornering Fatigue Test) and RFT(Radial Fatigue Test) had been satisfied. That is, the uni-axial component test could not forecast the crack of vehicle. Therefore this study developed the bi-axial test mode to reflect a vehicle condition(to reflect both vertical and lateral force simultaneously) based on real load data which was measured in Europe and China and developed CAE simulation too. It reproduced the cracks same as vehicle's and verified by bi-axial test machine in the LBF(Fraunhofer Institute for Structural Durability and System Reliability) durability research center in Germany. Finally this the durability CAE simulation by using HMC(Hyundai Motor Company)'s the bi-axial test mode predicts feasibly the steel wheel's durability performance before vehicle durability test.

• Computers and Concrete
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• 제21권2호
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• pp.117-126
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• 2018

This research investigate the behavior of reinforced normal and lightweight aggregate concrete hollow core slabs with different core shapes, shear span to effective depth (a/d). The experimental work includes testing seven reinforced concrete slabs under two vertical line loads. The dimensions of slab specimens were (1.1 m) length, (0.6 m) width and (0.12 m) thickness. The maximum reduction in weight due to aggregate type was (19.28%) and due to cross section (square and circular) cores was (17.37 and 13.64%) respectively. The test results showed that the decrease of shear span to effective depth ratio from 2.9 to 1.9 for lightweight aggregate solid slab cause an increase in ultimate load by (29.06%) and increase in the deflection value at ultimate load or the ultimate deflection by (17.79%). The use of lightweight aggregate concrete in casting solid slabs give a reduction in weight by (19.28%) and in the first cracking and ultimate loads by (16.37%) and (5%) respectively for constant (a/d=2.9).The use of lightweight aggregate concrete in casting hollow circular core slabs with constant (a/d=2.9) (reduction in weight 32.92%) decrease the cracking and ultimate loads by (12%) and (5.18%) respectively with respect to the solid slab. These slab specimens were analyzed numerically by using the finite element computer program ANSYS. Good agreements in terms of behavior, cracking load (load at first visible crack) and ultimate load (maximum value of testing load) was obtained between finite element analysis and experimental test results.

• 한국안전학회지
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• 제23권3호
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• pp.58-64
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• 2008

In order to identify the exact behavior of corbel section, the horizontal force acting on corbel section should be considered as well as the vertical force. In this study, a new corbel section, which is economical and easy to construct, is developed by evaluating the exact strength of the section. Experiments were performed to verify the strengths of the proposed sections comparing with those of the currently used section. The summary of the experiment results are as follows: 1) In order to minimize the horizontal force effect, it was found that the use of pre-stressing was most effective, and that TB type corbel section is a most efficient section in terms of economy and workability. 2) The experimentally obtained strength of corbel section matched well with that estimated using shear friction theory. Therefore, it is concluded that shear friction theory would be very useful if a precise crack angie in the corbel section, which is pre-stressed by PS strings and threaded bolts, is available.

• 대한기계학회논문집A
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• 제21권3호
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• pp.439-446
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• 1997

A traditional notion of composites has been composed as a uniform dispersoid, but now it is proposed without regard to such rule with process development. Functionally Graded Material(FGM) consists of a new material design that is to make intentionally irregular dispersion state. In this study, thermal stress analysis of plasma spraying PSZ/NiCrAlY gradient material was conducted theoretically using a finite-element program. A formations of the model are direct bonding material(NFGM) and FGM with PSZ and NiCrAlY component element. The temperature conditions were $700^{\circ}C$ to 1100.deg. C assuming a cooling-down precess up to room temperature. Fracture damage mechanism was analyzed by the parameters of residual stress.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 1998년도 특별강연 및 추계학술발표 개요집
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• pp.288-291
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• 1998

Inconel 600 alloy is used as the material of nuclear steam generator tubing because of its mechanical properties, formability, and corrosion properties. According to reports, the life time of nuclear power plants decreases because of the pitting, intergranular attack, primary water stress corrosion cracking(PWSCC), and intergranular stress corrosion cracking(IGSCC), and denting in the steam generator. The SCC test is very important because of SCC appears in various environment such as solutions, materials, and stress. The C-Rig specimen was made of the steam generator welded sleeve repairing by the pulsed Nd:YAG laser. In the corrosion invironment, corrosion solutions are Primary Water, Caustic, and Sulfate solution and corrosion time is 1624-4877hr. The permitted stress is 30-60ksi.In this C-Ring SCC test is the relationship between corrosion depth, crack and corrosion environment is evaluated. SCC was happens in Sulfate and Corrosion solution but doesn't happen in Primary Water. The corrosion time and stress is very affected by the severely environment of Sulfate or Caustic solution. The microstructure observation indicates that SCC causes interganular failure in the grain boundary of vertical direction.

• 콘크리트학회지
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• 제4권4호
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• pp.171-179
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• 1992

본 연구에서는 전단-스팬비가 1.5에서 2.5 범위의 고강도 콘크리트 보에 대해 기존 규준식의 안전여부를 확인하고, 사균열강도와 극한전단강도를 결정하기 위해 총 15개의 시험체를 제작하여 실험적 연구를 수행하였다. 주요변수는 전단-스팬비(a/d=1.5, 2.0, 2,5)와 수직전단철근비(Rv=0, 25, 50, 75, 100%, Rv=[$ ho$v / $\rho$v(ACI)] 100)이며, 콘크리트 압축강도(f＇c=747kg/$ extrm{cm}^2$와 인장철근비($\rho$w=0.0377)는 일정하다. 실험결과 본 연구의 전단-스팬비의 범위에서 ACI 318-89 (11-31)식은 일반적으로 수직전단철근에 의해 저항되는 전단강도를 상당히 과소평가하는 것으로 나타났다. 따라서 수직전단철근에 대한 영향이 재고되어야 할 것이다.

• 콘크리트학회지
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• 제10권6호
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• pp.161-168
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• 1998

본 연구는 수직전단하중에 대한 프리캐스트 바닥판간 이음부거동을 규명하고 수직전단력 전달에 유리한 이음부 구조도출을 위해 female-female 형식의 이음부를 제안하고, 실험 및 유한요소해석을 수행한 것이다. 경사각, 이음부깊이/높이 및 구속응력을 변수로 총 18개의 실험체에 대한 실험 및 유한요소해석결과 ,이음부의균열저항성 개선을 위해서는 경사각이 60。, D/H가 1/4일 경우가 유리하며 측방향구속으로 이음부를 압축상태로 유지하는 것이 이음부 균열방지에 효과적임을 알았다.

• 콘크리트학회지
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• 제3권2호
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• pp.115-121
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• 1991

보-기둥 접합부에서 보의 축방향 철근의 슬립은 정하중 및 동하중 하에서 철근 콘크리트 골조를 손상시키는 중요한 요인중 하나이다. 이 논문은 이형철근의 국부 부착-슬립 특성에 관한 콘크리트강도 및 보강철근에 대해 실행된 실험결과를 요약하였다. 실험결과로부터 부착할렬균열(bond splitting crack)이 기둥은 축방향 철근에 의해 제어되는 한 횡방향 보강철근이 국부부착거동에 직접적인 영향을 미치지 않으며 극한부착강도는 콘크리트강도의 콘크리트강도의 제곱근에 비례해 증가함을 알 수 있었다. 이를 근거로 압축강도에 따른 보강철근 내부의 콘크리트와 이형철근의 국부 부착 응력-슬립 상관관계를 나타내는 실험모델을 유도하였다.