• Journal of Welding and Joining
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• 제29권4호
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• pp.73-79
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• 2011

Friction stir welding (FSW) is a solid state joining method patented in 1991 by The Welding Institute (TWI). It is widely used for joining light metals such as Al and Mg alloys. Foreign railway vehicle manufacturing companies have been applying FSW to car body welding, but domestic companies are in the beginning of feasibility study. Therefore, lots of experimental and analytical study is needed. In this study, three-dimensional finite element modeling of the friction stir welding of two Al6061-T6 plates was carried out. And temperature field and residual stresses were obtained and compared to experimental results in the literature. It is found the analytic thermal field is in a good agreement with the experimental results, but there are some differences between numerical and experimental residual stresses.

• Steel and Composite Structures
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• 제12권3호
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• pp.249-260
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• 2012

In this study, stress and deflection behaviours of T-type welding joint applied to HE200M steel beam and column were investigated in finite element method (FEM) under different distributed loads. In the 3D-FEM modelling, glue option was used to contact between steel materials and weld nuggets. Geometrical model was designed as 3-dimensional solid in ANSYS software program. After that, homogeneous, linear and isotropic properties were used to design to materials of model. Solid-92 having 3-dimensional, 4 faced and 10-noded was selected as element type. In consequence of mesh operation, elements of 13285 and nodes of 28086 were occurred. Load distribution was applied to top surface of steel beam to determine behaviours of stress and deflection. As a result of FEM analysis applied with the loads of 55,000 N, 110,000 N and 220,000 N, maximum values were obtained as 116 N/$mm^2$, 232 N/$mm^2$ and 465 N/$mm^2$ for stress and obtainedas 1,083 mm, 2,166 mm and 4.332 mm for deflection, respectively. When modelling results and classical calculation values were compared, it was obtained difference of 10 % for stress values and 2.5% for deflection values.

• Computers and Concrete
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• 제13권4호
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• pp.569-585
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• 2014

In this paper, a four-layer road structure consisting of an edge transverse crack is simulated using three-dimensional finite element method in order to capture the influence of a single-axle wheel load on the crack propagation through the asphalt concrete layer. Different positions of the vehicular load relative to the cracked area are considered in the analyses. Linear elastic fracture mechanics (LEFM) is used for investigating the effect of the traffic load on the behavior of a crack propagating within the asphalt concrete. The results obtained show that the crack front experiences all three modes of deformation i.e., mode I, mode II and mode III, and the corresponding stress intensity factors are highly affected by the crack geometry and the vehicle position. The results also show that for many loading situations, the contribution of shear deformation (due to mode II and mode III loading) is considerable.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2002년도 춘계학술대회 논문집
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• pp.8-11
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• 2002

In this study, Automatic design program creates 3D solid models and constructs them. The method of making assembly model is two. One assembles the element made in automatic design program with hand, the other develops the automatic design program for creating assembly model. Automatic design program improves the convenience of user. In creating gears, involute ewe and Trochoidal fillet curve are made by mathematical development.

• Structural Engineering and Mechanics
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• 제31권3호
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• pp.349-365
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• 2009

Membrane structures are quite sensitive to wind and therefore the fluid-solid interaction can not be neglected in dynamic analysis. A boundary element method (BEM) for 3D simulation of wind-structure interaction in tensile membrane structures is presented in this paper. The flow is treated as incompressible and potential. The flow field is solved with boundary element method codes and structural simulation is performed by finite element method software ANSYS. The nonlinear equations system is solved iteratively, with segregated treatment of the fluid and structure equations. Furthermore this method has been demonstrated to be effective by typical examples. Besides, the influence of several parameters on the wind-structure interaction, such as rise-span ratio, prestress and the wind velocity are investigated according to this method. The results provide experience in wind resistant researches and engineering.

• Architectural research
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• 제11권1호
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• pp.15-23
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• 2009

An application of the constrained adaptive topology optimization (CATO) algorithm is described for three-dimensional topology optimization of engineering structures. The enhanced assumed strain lower order solid finite element (FE) is used to evaluate the values of objective and constraint functions required in optimization process. The strain energy (SE) terms such as elastic and modal SEs are employed as the objective function to be minimized and the initial volume of structures is introduced as the constraint function. The SIMP model is adopted to facilitate the material redistribution and also to produce clearer and more distinct structural topologies. The linearly weighted objective function is introduced to consider both static and dynamic characteristics of structures. Several numerical tests are tackled and it is used to investigate the performance of the proposed three-dimensional topology optimization process. From numerical results, it is found to be that the CATO algorithm is easy to implement and extremely applicable to produce the reasonable optimum topologies for three dimensional optimization problems.

• 한국정밀공학회지
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• 제18권4호
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• pp.129-134
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• 2001

It is essential to predict the welding deformation at assembly stage, to increase productivity through mechanization and automation effectively. A practical analysis method appled for production engineering was proposed to simulate the deformation of arc welding, with an analytical model using finite element method solving thermal-elastic-plastic behavior. In this research, for accurate assembling, 3-D thermal-elastic-plastic finite element model is used to simulate the out-of-plane deformation caused by arc welding. Efforts have been made to find out the efficient method to improve the reliability and accuracy of the numerical calculation. Each of theories of small and large deformation is applied in solving 3-D thermal-elastic-plastic problem to compare with their efficiency about calculation imes and solution accuracy. When solid elements are used in a bending problem of a plate, phenomenon that the predictive deformation is more than that of actual survey is observed. To prevent this phenomenon, reduced integration method for element is employed instead of full integration that is generally used in 3-D thermal-elastic-plastic analysis.

• 한국산학기술학회논문지
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• 제10권9호
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• pp.2183-2188
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• 2009

본 논문은 3차원 균열의 유한요소해석을 위한 자동요소분할시스템에 대한 것으로, 논문의 구성은 퍼지지식처리, 버블메슁, 솔리드모델러로 구성된다. 새로운 요소분할과정은 (a) 해석모델인 기하학적 모델 정의, (b) 버블생성, (c), 요소분할로 구성되어 진다. 3차원 균열체를 위해 범용솔리드 모델러를 사용하였으며 버블은 존재하는 버블점들간의 거리가 그 점에서의 버블간격 함수와 유사한지를 결정하여 발생되어 진다. 버블간격 함수는 퍼지지식처리에 의해 잘 조절되어 진다. 요소생성에 관한 기본 툴로서는 데로우니기법이 사용되었다. 시스템의 실제적인 효용성을 검증하기 위해 3차원 균열에 대한 몇가지 예를 나타내었다.

• 소성∙가공
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• 제8권3호
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• pp.294-305
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• 1999

A vision-based surface-strain measurement system has been still improved since the authors devel-oped the first version of it. New algorithms for the subpixel measurement and surface smoothing are introduced to improve the accuracy and precision in the present study. The effects of these algorithms are investigated by error analysis. And the equations required to calculate 3D surface-strain of a shell element are derived from the shape function of a linear solid finite-element. The influences of external factors on the measurement error are also examined, and several trials are made to obtain possible optimal condition which may minimize the error.

• Journal of Electrical Engineering and Technology
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• 제13권3호
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• pp.1275-1284
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• 2018

The coaxial magnetic gear with the flux concentrating structure is known that it has the torque performance advantage over the coaxial magnetic gear having surface mounted permanent magnet, thanks to the flux focusing effect. But, if the solid cores are used in the modulating pieces and rotor cores to consider the mechanical reliability and cost reduction, the operating torque of the flux concentrating coaxial magnetic gear can be significantly diminished because the iron losses at the solid cores affect the actual transmitted torque. Furthermore, the modulating pieces and rotor cores have different characteristics of the iron losses from one another, because the space harmonic components of the magnetic flux density, which cause the iron losses, are different. Thus, in this paper, we focused on the analysis of the characteristics of the space harmonic components of the magnetic flux density and resultant eddy current losses in the surface mounted PM and flux concentrating coaxial magnetic gears, when these coaxial magnetic gears have the solid cores at the modulating pieces and rotor cores. The characteristics of pull-out torque (static torque), operating torque (dynamic torque), and efficiency are also researched, and compared by the 3D finite element analysis (FEA) and experiment.