• Journal of Welding and Joining
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• 제26권3호
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• pp.67-73
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• 2008

Fatigue life evaluation of welded structures in a range of high cycles is one of the most difficult problems since extremely small plastic deformation and damage occur during the loading cycles. Moreover, it is very difficult to identify the strong non-linearities of welding, inducing residual stress. In this paper, numerical fatigue test method for welded structures was developed using continuum damage mechanics with inherent strain. Recently, continuum damage mechanics, which can simulate both crack initiation at the micro-scale level and crack propagation at the meso-scale level, has been adopted in the fracture related problem. In order to consider the residual stresses in the welded strictures, damage calculation in conjunction with welding, inducing inherent strain, was proposed. The numerical results obtained from the damage calculation were compared to experimental results.

• 대한조선학회논문집
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• 제46권5호
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• pp.498-509
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• 2009

Present study is concerned with the simulation of plasticity models for the cyclic stressstrain behavior of aluminum alloy AC4C-T6 that can be used for primary materials of LNG cargo pump. Material model of cyclic hardening and plasticity for aluminum alloy AC4C-T6 was investigated through experiments and numerical simulations. Monotonic tensile and cyclic tension-compression test under symmetric load cycles was performed at both room temperature and cryogenic temperature of $-165^{\circ}C$. Based on the experimental data plastic hardening models were evaluated for isotropic/kinematic/combined hardening. FEA (Finite Element Analysis) models which describe the cyclic stress-strain relationship were evaluated for the simulation of plasticity. An appropriate hardening model is proposed comparing the results of FEA with those of experiments.

• 한국실내디자인학회논문집
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• 제14호
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• pp.130-136
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• 1998

The stepping stone of the study is provided through understanding the transformation of the cultural value with the paradigm shift at the turning point of late 20th century and examining the cultural relationaship between the East and the West. By researching the oriental and occidental culture in terms of the origin formation relation and differences which should be divided into broad branches that is natural ideological formative and spatial aspects and so forth. This paper makes it possible to understand the fundamental differences and relativities between two divergent cultures by way of analyzing the architecture in plastic and cognitive aspects to residential space. this study intends to elucidate common traits of korean traditional architecture and that of the Occident and the discrepancies of their attitudes toward nature and space. In Western civilization they used to consider architecture as a physical organization while the oriental people consider it a object what is so of itself. The former concentrated on the functional rationality of scientific technology with the uncontextual propensity which does not consider natural environment the latter could reach the naturalness more harmonious to environment. What counts in the upcoming age of coexistence of Globalism that emphasizes the worlds universality and Nationalism that sticks to local cultural characteristics is to establish the new value system and identity based upon natural order and organic quality. As a result we could recognize the organic quality as a cosmic order could be a valid means to achieve the globalization of our culture through the compatibility between gap and common ground of both cultural sphere.

• Steel and Composite Structures
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• 제24권1호
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• pp.1-13
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• 2017

In order to improve the deformation capacity of the high-strength concrete shear wall, five high-strength concrete shear wall specimens confined with high-strength rectangular spiral reinforcement (HRSR) possessing different parameters, were designed in this paper. One specimen was only adopted high-strength rectangular spiral hoops in embedded columns, the rest of the four specimens were used high-strength rectangular spiral hoops in embedded columns, and high-strength spiral horizontal distribution reinforcement were used in the wall body. Pseudo-static test were carried out on high-strength concrete shear wall specimens confined with HRSR, to study the influence of the factors of longitudinal reinforcement ratio, hoop reinforcement form and the spiral stirrups outer the wall on the failure modes, failure mechanism, ductility, hysteresis characteristics, stiffness degradation and energy dissipation capacity of the shear wall. Results showed that using HRSR as hoops and transverse reinforcements could restrain concrete, slow load carrying capacity degeneration, improve the load carrying capacity and ductility of shear walls; under the vertical force, seismic performance of the RC shear wall with high axial compression ratio can be significantly improved through plastic hinge area or the whole body of the shear wall equipped with outer HRSR.

• Earthquakes and Structures
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• 제16권1호
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• pp.83-96
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• 2019

The seismic behavior of PRC coupling beam-hybrid coupled shear wall system is analyzed by using the finite element software ABAQUS. The stress distribution of steel plate, reinforcing bar in coupling beam, reinforcing bar in slab and concrete is investigated. Meanwhile, the plastic hinges developing law of this hybrid coupled shear wall system is also studied. Further, the effect of coupling ratio, section dimensions of coupling beam, aspect ratio of single shear wall, total height of structure and the role of slab on the seismic behavior of the new structural system. A fitting formula of plate characteristic values for PRC coupling beams based on different displacement requirements is proposed through the experimental date regression analysis of PRC coupling beams at home and abroad. The seismic behavior control method for PRC coupling beam-hybrid coupled shear wall system is proposed based on the continuous connection method and through controlling the coupling ratio, the roof displacement, story drift angle of hybrid coupled shear wall system, displacement ductility of coupling beam.

• Journal of Welding and Joining
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• 제24권5호
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• pp.57-61
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• 2006

For the production of functional $TiO_2$-biodegradable plastic (polybutylene succinate:PBS) composite material with photocayalytic activity, we attempted to prepare $TiO_2$ coatings on PBS substrate by HVOF and plasma spraying techniques under various conditions. The microstructures of coatings were characterized with SEM and XRD analysis, and the photocatalytic efficiency of coatings was evaluated by the photo degradation of gaseous acetaldehyde. The effects of primary particle size and spraying parameters on the formation behavior, photocatalytic performance of the coatings have been investigated. The results indicated that for both the HVOF sprayed $P_{200}$ and $P_{30}$ coatings, the high anatase ratio of 100% can be achieved regardless of fuel gas pressure. On the other hand, the HVOF sprayed $P_7$ coating exhibited a largely decreased anatase ratio (from 100% to 49.1%) with increasing the fuel gas pressure, which may be attributed to much higher susceptibility of heat for 7 nm agglomerated powder. HVOF sprayed $P_{200}$ and $P_{30}$ coatings show better performance as compared to that of plasma sprayed $P_{200}$ coatings owing to the higher anatase ratio. However, the HVOF sprayed $P_7$ coatings did not show the photocatalytic activity, which may result from the extremely small reaction surface area to the photocatalytic activity and low anatase ratio.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2012년도 춘계학술대회
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• pp.225-226
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• 2012

최근 국내에서 섬유강화유리플라스틱(GRP)을 주로 사용하여 해양레저선박 및 구조물에 대한 건조가 이루어지고 있다. 하지만 해양레저 선박에 대한 구조강도 평가의 관심이 다소 미흡하다. 따라서 국내 실정에 적합한 구조강도평가기법을 정립하고 국내 규정 중 한국선급(KR)의 해양레저선박지침과 국토해양부의 강화플라스틱선 구조기준을 적용하여 구조설계 및 유한요소해석을 수행하여 신뢰성을 확보하고자 하였다.

• 콘크리트학회논문집
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• 제24권3호
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• pp.241-248
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• 2012

이 연구에서는, 철근콘크리트 기둥 실험체를 대상으로 기둥의 휨 위험 단면부에 국부적으로 강섬유 시멘트모르타르를 적용함으로서 기존 철근콘크리트 기둥에 비해 내진성능이 우수한 강섬유 모르타르 적용 철근콘크리트 복합기둥공법에 관해 제시하였다. 제시된 적용공법의 성능검증을 위하여 기존 철근콘크리트 기둥 1개 및 소성힌지구간에 국부적으로 강섬유 모르타르를 적용한 복합기둥 실험체 2개를 제작하여 일정 축하중 하에서 횡방향 반복하중을 받는 재하시험을 수행하였다. 콘크리트 및 강섬유 모르타르는 모두 현장타설되었다. 재하시험 결과 기존 철근콘크리트 기둥 실험체와 비교하여 강섬유 모르타르 적용 철근콘크리트 복합기둥 실험체의 경우 휨 및 전단 균열의 제어에 우수할 뿐만 아니라 기둥의 횡하중 내력 및 횡방향 변형 능력 향상에서도 우수한 것으로 평가되었다.

• 대한조선학회논문집
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• 제50권1호
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• pp.41-48
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• 2013

Several fatigue damages have recently been reported which cannot be resolved in the context of the existing fatigue design procedure, and they are suspected to be the cracks induced by the low cycle fatigue mechanism. To tackle the problem, a series of material tests together with fatigue tests have been carried out, and elasto-plastic notch strain analysis using nonlinear kinematic hardening model has been performed. The cyclic stress-strain curves are obtained and the nonlinear kinematic hardening model was calibrated based on the obtained material data. Also, the fatigue test with non-load-carrying cruciform fillet welded joint has been performed in low cycle fatigue regime. Then, the notch strain analyses have been carried out to find the precise elasto-plastic behavior of the material at the notch root of the cruciform joint. The variation of the material property from the base metal via HAZ up to the weld metal was taken into account using spatial variation of the material property. Then the detail elasto-plastic behavior of the welded joint subjected to the repeated cyclic loading has been investigated further through the comparison with the prediction with Neuber's rule. The calibration of the nonlinear kinematic hardening model and nonlinear notch strain analyses have been performed using the commercial FE program ABAQUS.

• 대한조선학회논문집
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• 제47권6호
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• pp.843-849
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• 2010

This paper presents definition of symmetry of a ship section where three symmetries are proposed: material, geometric, and load symmetries. Precise terminologies of centroid, moment plane, and neutral axis plane are also defined. It is suggested that force vector equilibrium as well as force equilibrium are necessary condition to determine new position of neutral axis due to translational and rotational mobility. It is also stated that new reference datum of ENMP(elastic neutral moment plane), PNMP(fully plastic moment plane), ENAP(elastic neutral axis plane), and INAP(inelastic neutral moment plane) are required to define asymmetric section properties such as second moment of area, elastic section modulus, yield moment, fully plastic moment, and ultimate moment. Since collision-induced damage and flooding-induced biaxial bending moment produce typical asymmetry of section, the section properties are calculated for a typical VLCC. Geometry asymmetry is determined from ABS and DNV rules and two moment planes of 0/30 degs are assumed for load asymmetry. It is proved that the property reduction ratios directly calculated from second moment of area are usually larger than area reduction ratio. Reduction ratio of ultimate moment capacity shows almost linearly proportional to area reduction ratio. Mobility of elastic and inelastic neutral axis planes is visually provided.