• Steel and Composite Structures
• /
• 제6권3호
• /
• pp.221-236
• /
• 2006

The objective of this work is to describe the main steps involved in the derivation of a GBT (Generalised Beam Theory) formulation to analyse the vibration behaviour of loaded cold-formed steel members and also to illustrate the application and capabilities of this formulation. In particular, the paper presents and discusses the results of a detailed investigation about the local and global free vibration behaviour of lipped channel simply supported columns. After reporting some relevant earlier GBT-based results dealing with the buckling and vibration behaviours of columns and load-free members, the paper addresses mostly issues concerning the variation of the column fundamental frequency and vibration mode nature/shape with its length and axial compression level. For validation purposes, some GBT-based results are also compared with values obtained by means of 4-node shell finite element analyses performed in the code ABAQUS.

• Structural Engineering and Mechanics
• /
• 제70권2호
• /
• pp.153-168
• /
• 2019

In this paper, energy absorption characteristics of circular windowed tubes with different section shapes (circular, ellipse, square, hexagon, polygon and pentagon) are investigated numerically and experimentally. The tube possesses the same material, thickness, height, volume and average cross sectional area which are subjected under axial and oblique quasi-static loading conditions. Numerical model was constructed with FE code ABAQUS/Explicit, the obtained outcome of simulation is in good matching with the experimental data. The energy absorbed, specific energy absorption, crash force efficiency, peak and mean loads along with the collapse modes with their initiation point of simple and windowed tubes were evaluated. The technique for order of preference by similarity ideal solution (TOPSIS) approach was employed for assessing their overall crushing performances. The obtained results confirm that efficacy of crash force indicators have improved by introducing windows and tubes with pentagonal and circular windows achieves the maximum ranking about 0.528 and 0.517, it clearly reveals the above are best window shapes.

• Structural Engineering and Mechanics
• /
• 제77권5호
• /
• pp.651-659
• /
• 2021

In this study, a new constitutive model has been developed to predict the elastic behavior of plain weave textile composites, using the finite element (FE) method. The geometric conditions and basic assumptions of this model are based on the basics of a continuum theory developed for the plane curved composites. In this model, the mechanical properties of the weave region and pure matrix region is calculated separately and then imported for the FE analysis. This new constitutive model is used to implement the mechanical properties of weave region in the representative volume element (RVE). The constitutive relations are implemented as user-material subroutine code (UMAT) in ABAQUS® FE software. The results of FE analysis have been compared with experimental results and other data available in the literature. These comparisons confirmed the capability of the presented model for the prediction of effective elastic properties of plain weave fabric composites.

• 한국분말재료학회지
• /
• 제30권1호
• /
• pp.29-34
• /
• 2023

A fixed-point iteration is proposed to integrate the stress and state variables in the incremental analysis of plastic deformation. The Conventional Newton-Raphson method requires a second-order derivative of the yield function to generate a complicated code, and the convergence cannot be guaranteed beforehand. The proposed fixed-point iteration does not require a second-order derivative of the yield function, and convergence is ensured for a given strain increment. The fixed-point iteration is easier to implement, and the computational time is shortened compared with the Newton-Raphson method. The plane-stress condition is considered for the biaxial loading conditions to confirm the convergence of the fixed-point iteration. 3-dimensional tensile specimen is considered to compare the computational times in the ABAQUS/explicit finite element analysis.

• Advances in materials Research
• /
• 제12권4호
• /
• pp.273-286
• /
• 2023

The fracture mechanics make it possible to characterize the behavior with cracking of structures using parameters quantifiable in the sense of the engineer, in particular the stress field, the size of the crack, and the resistance to cracking of the material. Any structure contains defects, whether they were introduced during the production of the part (machining or molding defects for example). The aim of this work is to determine numerically by the finite element method the stress concentration factor Kt of a plate subjected to a tensile loading containing a lateral form defect with different sizes: a semicircle of different radii, a notch with different opening angles and a crack of different lengths. The crack propagation is then determined using the extended finite element technique (X-FEM). The modeling was carried out using the ABAQUS calculation code.

• 국제초고층학회논문집
• /
• 제12권3호
• /
• pp.235-239
• /
• 2023

In this study, the fire resistance performance of the concrete-filled steel tube (CFT) columns and thin steel-plate composite (TSC) beams installed at a 20-story office building were designed using a performance-based structural fire design. Because of the lack of any specific provisions in the building code and guidelines for structural engineers about the performance-based approach, the only prescriptive approach has been selected for designing fire-resistant structures in Korea. To evaluate the fire resistance performance of the CFT columns and TSC beams, finite element analysis verified by the experimental results studied by several researchers was conducted with ABAQUS. From the fire scenario, the temperature distributions of the CFT columns and TSC beams were found via finite element analysis and the behaviors of the CFT columns and TSC beams were investigated in the structural field based on the temperature distribution.

• 방사성폐기물학회지
• /
• 제13권2호
• /
• pp.99-112
• /
• 2015

본 연구에서는 고준위폐기물 처분시 완충재로 사용되는 벤토나이트의 열적 거동을 평가하기 위해 실내실험장치를 제작하였다. 그리고 실험 결과를 검증하기 위해 유한요소해석 프로그램인 ABAQUS를 이용한 열해석을 실시하였다. 그리고 실험기간 동안의 계절변화를 감안하여 외부대기 온도에 따른 벤토나이트의 열적거동을 평가하였다. 해석결과, 스테인리스스틸이 포함된 case3 해석모델의 결과가 실험결과와 1℃ 내외의 오차를 보이며 거의 일치함을 볼 수 있었다. 그리고 계절에 따른 벤토나이트 온도 해석을 수행한 결과, 시간에 따른 온도분포 경향이 일치함을 확인하였다. 이러한 열해석을 통해 완충재를 둘러싸고 있는 물질의 열전도도와 외부대기의 온도가 벤토나이트 완충재의 열적 거동에 큰 영향을 주는 요소임을 확인할 수 있었다. 향후 열원을 포함한 벤토나이트 완충재의 수분 포화 특성 실험이 실시 될 예정이므로, 실험에 대한 검증과 예측을 위해 보다 적합한 수치해석모델 개발에 대한 연구가 필요할 것이다.

• Composites Research
• /
• 제17권1호
• /
• pp.29-37
• /
• 2004

하니컴 샌드위치 복합재료(HSC) 구조물은 높은 강성 및 경량화가 요구되는 항공ㆍ우주 및 군수 산업 등에 폭 넓게 이용되고 있으며 하니컴 샌드위치 복합재료의 정확한 강도 해석에 있어서 하니컴 코어의 기계적 물성 예측이 필요하다. 본 연구에서는 하니컴 코어 벽의 굽힘, 축 방향 및 전단 변형을 고려한 에너지 법을 사용하여 하니컴 코어 재료의 각 방향 탄성계수 및 포아송 비와 같은 기계적 물성 값을 구하기 위한 예측식을 유도하고, 이 이론 예측값이 유한요소 해석 프로그램인 ABAQUS 6.3을 이용하여 구한 결과와 거의 일치하고 있음을 알았다. 또한 하니컴 샌드위치 복합재료 평판의 인장 실험 및 유한요소 시뮬레이션을 수행하여 변형 거동 예측 및 층간 응력을 해석하였다. 하니컴 코어층과 표면층 사이의 전단 응력의 증가는 HSC 평판의 층간분리 현상의 주원인임을 알 수 있었다.

• 터널과지하공간
• /
• 제10권2호
• /
• pp.237-248
• /
• 2000

역학적으로 안정한 공동 및 처분공 간격을 결정하기 위해, 현재 수행 중인 열 해석의 중간 결과를 근거로 범용 해석 프로기램인 ABAQUS 버전 5.8을 이용해 3차원 유한요소해석을 수행하였다. 세 가지 초기지압을 조건으로 공동간격과 처분공 간격을 바꿔가면서 선형탄성해석을 수행하였고. 그 결과를 분석하여 굴착 후 응력재분배에 의한 암반의 거동은 어떤 경향을 가지고 있으며, 적절한 공동 간격 및 처분공 간격은 어느 정도가 좋은지를 분석하였다. 또한 각 경우 역학적인 안전계수는 어느 정도인지도 계산하였다. 국내지압분포를 근거로 도출한 초기지압 하에서는 공동간격 40m, 처분공간격 3m인 경우 안전계수 3.42가 계산되어 아주 안정한 결과를 얻었고, 스웨덴이나 캐나다의 초기지압 경힘식의 경우의 안전계수는 각각 1.19와 1.27로 비교적 낮은 값이지만 1 이상의 값이므로 응력재분배로 인한 파괴는 일어나지 않는다는 결과를 얻었다.

• 한국자동차공학회논문집
• /
• 제22권1호
• /
• pp.117-125
• /
• 2014

The temperature distribution of steady state rolling tires with detailed tread blocks is numerically predicted using the three dimensional full patterned tire model. A three dimensional periodic patterned tire model is constructed by copying 1-sector mesh in the circumferential direction. Using the static tire contact analysis, the strain cycles during one revolution are approximated with the strains at Guassian points of the elements which are sector-wise repeated within the same circular ring of elements, by neglecting the tire rolling effect. Based upon the multi-axial fatigue theory, the maximum principal strain is used to represent the combined effect of six strain components on the hysteretic loss. In the following, the deformation due to the inflation and vertical load is calculated using ABAQUS. Then heat generation rate in each element is calculated using an in-house code. Lastly, temperature distribution is calculated using ABAQUS again. Through the numerical experiments, the validity of the proposed prediction method is examined by comparing with the experiment and the temperature distribution of a patterned tire model is compared with those of the main-grooved simple tire model.