• 대한토목학회논문집
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• 제13권2호
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• pp.41-49
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• 1993

2차원 곡선보요소를 이용하여 대변형효과 및 탄소성거동을 고려한 유한요소법을 제시한다. Total Lagrangian 방법을 적용하며, 보요소는 평면응력요소로부터 유도된다. 또한, 임의의 단면을 갖는 평면뼈대 구조의 탄소성 해석을 수행하기 위하여 layered approach를 사용한다. 비선형 유한요소해석은 하중증분 또는 변위증분법을 적용한다. 본 연구에서 제안한 보요소의 거동과 정확도를 검증하기 위하여, 다른 문헌의 결과와 본 연구의 결과를 비교 분석한 해석예제를 제시한다.

• 한국전산구조공학회논문집
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• 제30권1호
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• pp.1-6
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• 2017

본 논문에서는 비교적 최근 정립된 co-rotational 이론을 기반으로 한 4절점 평면요소 정식화를 확장하여 9절점 평면 요소에 적합한 CR 정식화를 제시하고자 한다. 그리고 등방성 재료의 소성 해석을 위해, 선형 경과 규칙(bi-linear hardening rule)을 바탕으로 하는 Newton-Raphson return-mapping 알고리즘을 적용하였다. 이때, von Mises 기준을 적용하여 소성 변형 상태를 예측하였다. Lagrange 승수를 도입하여 2차원 접촉에 대한 구속조건을 부여하였다. 개발한 요소는 상용프로그램인 ABAQUS 해석결과와 비교 검증하였다.

• 대한토목학회논문집
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• 제28권1A호
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• pp.115-123
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• 2008

최근 섬유강화 복합재료의 특성예측은 많은 공학자들에게 관심의 대상이 되고 있으며, 섬유강화 복합재료의 특성을 예측하기 위한 다양한 이론적, 수치적 방법들이 제안되고 있다. 본 연구에서는 복합재료내 구성요소를 고려한 Ju and Zhang (2001)의 미세역학 모델을 개선하고 원형섬유와 매트릭스간의 점진적인 손상을 고려하여 원형섬유강화 복합재료의 탄소성거동 및 점진적 손상해석을 위한 미세역학 모델을 개발하였다. 제안된 해석모델을 이용하여 다양한 수치해석을 통해 원형섬유강화 복합재료의 탄소성거동 및 점진적 손상을 예측하였고 손상을 고려하지 않은 모델과의 비교를 통하여 점진적 손상이 복합재료의 탄소성거동에 미치는 영향을 검토하였다.

• Tribology and Lubricants
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• 제40권1호
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• pp.8-16
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• 2024

This study conducts numerical modeling and eigen-analysis of a rod-fastened rotor, which is mainly used in aircraft gas turbine engines in which multiple disks are in contact through curvic coupling. Nayak's theory is adopted to calculate surface parameters measured from the tooth profile of the curvic coupling gear. Surface parameters are important design parameters for predicting the stiffness between contact surfaces. Based on the calculated surface parameters, elastoplastic contact analysis is performed according to the interference between two surfaces based on the Greenwood-Williamson model. The equivalent bending stiffness is predicted based on the shape and elastoplastic contact stiffness of the curvic coupling. An equation of motion of the rod-fastened rotor, including the bending stiffness of the curvic coupling, is developed. Methods for applying the bending stiffness of a curvic coupling to the equation of motion and for modeling the equation of motion of a rotor that includes both inner and outer rotors are introduced. Rotordynamic analysis is performed through one-dimensional finite element analysis, and each element is modeled based on Timoshenko beam theory. Changes in bending stiffness and the resultant critical speed change in accordance with the rod fastening force are predicted, and the corresponding mode shapes are analyzed.

• 소성∙가공
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• 제28권3호
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• pp.115-122
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• 2019

In this paper, finite element analysis of an automatic five-stage precision cold forging process of a yoke, a steering part of a passenger's car, is conducted with emphasis on spring back analysis at the yoke-forming stage and its experimental verification is subsequently made. An elastoplastic finite element method with MINI-element technique employed for the analysis of the entire process is explained. There is emphasis that the thin film of material formed between the punch and die in the stage may result to some errors especially in elastoplastic finite element analysis of spring back due to frequent remeshing. The numerical robustness of the spring back analysis in regards to remeshing is hence shown first through investigation into its effect on the predicted spring back. Experimental measurement of displacement due to spring back is carried out for comparison with the predicted results, and they are in a qualitative agreement with each other.

• Earthquakes and Structures
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• 제17권1호
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• pp.39-48
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• 2019

This paper presents an experimental study on a 1/2 scale steel frame with archaized-style under the pseudo-dynamic loading. Four seismic waves, including El Centro wave, Taft wave, Lanzhou wave and Wenchuan wave, were input during the test. The hysteresis characteristic, energy dissipation acceleration response, displacement response, strength, stiffness and strain were analyzed. Based on the experiment, the elastoplastic dynamic time-history analysis was carried out with the software ABAQUS. The stress distribution and failure mode were obtained. The results indicate that the steel frame with archaized-style was in elastic stage when the peak acceleration of input wave was no more than 400 gal. Under Wenchuan wave with peak acceleration of 620 gal, the steel frame enters into the elastoplastic stage, the maximum inter-story drift was 1/203 and the bearing capacity still tended to increase. During the loading process, Dou-Gong yielded first and played the role of the first seismic fortification line, and then beam ends and column bottom ends yielded in turn. The steel frame with archaized-style has good seismic performance and meets the seismic design requirement of Chinese code.

• Geomechanics and Engineering
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• 제37권1호
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• pp.1-8
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• 2024

Buckling failure is one of the classical types of catastrophic landslides developing on inclination-paralleled rock slopes, which is mainly governed by its self-weight, earthquake and ground water. However, nearly none of the existing studies fully consider the influence of slope self-weight, earthquake and ground water on the mechanical model of buckling failure. In this paper, based on energy equilibrium principle and elastoplastic slab theory, a thorough mechanical analysis on bucking slopes has been carried out. Furthermore, an analytical solution for slip bucking failure of rock slopes has been proposed, which fully considers the effect of slope self-weight, seismic force and hydrostatic pressure. Finally, the methodology is used to conduct comparative analysis with other analytical solutions for three practical buckling studies. The results show that the proposed approach is capable of providing a more accurate and reasonable evaluation for stability of rock slopes with potential buckling failure.

• Geomechanics and Engineering
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• 제36권2호
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• pp.121-130
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• 2024

Many foundation projects are built on red-bed soft rocks, and the damage evolution of this kind of rocks affects the safety of these projects. At present, there is insufficient research on the damage evolution of red-bed soft rocks, especially the progressive process from mesoscopic texture change to macroscopic elastoplastic deformation. Therefore, based on the dual-porosity characteristics of pores and fissures in soft rock, we adopted a cellular automata model to simulate the propagation of these voids in soft rocks under an external load. Further, we established a macro-mesoscopic damage model of red-bed soft rocks, and its reliability was verified by tests. The results indicate that the relationship between the number and voids size conformed to a quartic polynomial, whereas the relationship between the damage variable and damage porosity conformed to a logistic curve. The damage porosity was affected by dual-porosity parameters such as the fractal dimension of pores and fissures. We verified the reliability of the model by comparing the test results with an established damage model. Our research results described the progressive process from mesoscopic texture change to macroscopic elastoplastic deformation and provided a theoretical basis for the damage evolution of these rocks.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 추계학술대회 논문집
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• pp.181-184
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• 2009

The hot press farming process, which is the press hardening of steel parts using cold dies, can utilize both ease of shaping and high strength due to the hardening effect of rapid quenching during the pressing. In this study, a thermo-elastoplastic analysis of the hot press forming process using the finite element method was performed in order to investigate the deformation behavior and temperature history during the process and the mechanical properties of the pressed parts.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2002년도 춘계 학술발표회 논문집
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• pp.109-116
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• 2002

Since experimental evaluation of underground RC structures considering interaction with surrounding soil medium is quite difficult to be simulated, the evaluation for the underground RC structures using an analytical method can be applied very usefully. For underground structures interacted with surrounding soils, it is important to consider path-dependent RC constitutive model, soil constitutive model, and interface model between structure and soil, simultaneously. In this paper, an elastoplastic interface model which consider thickness of interface is proposed and applied for the analysis considering the interaction. Failure mechanism of underground RC box of two story and two box subway station under seismic action is obtained and the effects of ductility of intermediate column to entire underground RC system are investigated through analysis.