• The Transactions of the Korean Institute of Electrical Engineers
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• v.35 no.11
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• pp.479-486
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• 1986

It is necessary to consider a rotor movement in dynamic analysis on the flux distribution of electric machinery by FEM. Therefore, if air-gap domain was subdivided into triangular elements, computation results contain errors due to variation of element shape in air-gap because the nodal points corresponding to the rotor are displaced in analyzing domain for the time difference. In order to reduce this errors, the paper presents a application of a Macro Air-gap Element that interpolation function is obtained analytically and a means to join it with linear triangular elements in the rotating machine or in the linear machine. At the end of paper, setting up analytic domain model, it compares analytic solution with the computation results of Macro Air-gap Element appliction and that of linear triangular element subdivision only to each cases of nodal displacement. And it carries out that errors due to variation of element shape are reduced effectively by application of a Macro air-gap element.

• Proceedings of the KWS Conference
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• 2007.11a
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• pp.26-28
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• 2007

This research is concerned with a study of failure strength evaluation on heat element gap at resistance welding. The failure strength of resistance welded joint is changed by welding factor like as current(power level), welding time(total energy), pressure etc. and another heat element factor like as number of element line, element gap etc. Tensile-shear tests were carried out with the single-lap specimen using polypropylene(PP). The failure mechanism and optimization of gap was discussed in order to explain the tensile-shear strength evaluation on heat element gap at resistance welding. Orthogonal array was used by fractional factorial design for efficient experiments.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1997.10a
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• pp.32-39
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• 1997

The coiling station of ISP coil box is an equipment that winds a hot bar rolled at reduction unit into a coil without mandrel. In the coiling process, the roll gap of the bending unit is a significant one of several factors that influence bar coiling. To obtain a good bar-coil, the roll gap must be set appropriately according to the bar thickness. In this study, with 2-dimensional isothermal elastic-plastic finite element method, authors investigated influence of the change of the roll gap on the initial coiling shapes and the formed inner diameters of coils. Based on finite element analysis, authors proposed the appropriate roll gap according to the bar thickness to be able to wind a hot bar. The inner diameters of coils by results of analysis comparatively agreed with coling operation conducted in plant.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.4
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• pp.667-676
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• 2002

Many studies on the finite element modeling for bolted joints have proceeded, but the structures with bolted joints are complicated in shape and it is difficult to find out the characteristics according to joint condition. Usually, experimental methods have been used for bolted joint analysis. A reliable and practical finite element modeling technique for structure with bolted joints is very important for engineers in industry. In this study, three kinds of model are presented; a detailed model, a practical model and a simple model. The detailed model is modeled by using 3-D solid element and gap element, and the practical model is modeled by using shell element (a portion of bolt head) and beam element (a portion of bolt body), the simple model is modeled by simplifying practical model without using gap elements. Among these models, the simple model has the least degree of freedom and show the effect of memory reduction of 59%, when compared with the detailed model.

• Steel and Composite Structures
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• v.26 no.2
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• pp.139-150
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• 2018

In this paper, two kinds of buckling restrained braces (BRBs) are designed to improve the mechanical properties and fatigue life, the reserved gap and viscoelastic filler with high energy dissipation capacity are employed as the sliding element, respectively. The fatigue life of BRBs considering the effect of sliding element is predicted based on Manson-Coffin model. The property tests under different displacement amplitudes are carried out to evaluate the mechanical properties and fatigue life of BRBs. At last, the finite element analysis is performed to study the effects of the gap and viscoelastic filler on mechanical properties BRBs. Experimental and simulation results indicate that BRB employed with viscoelastic filler has a higher fatigue life and more stable mechanical property compared to BRB employed with gap, and the smaller reserved gap can more effectively improve the energy dissipation capacity of BRB.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.943-946
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• 2007

The vibration and noise characteristic of the Axial-gap motor for an air conditioner were analyzed. Experimental Modal Analysis was performed to understand the vibration characteristic of the motor. The noise of motor was measured in a dead room. Finite Element Method was performed to find the vibration characteristic of the motor by using ABAQUS program.

• Steel and Composite Structures
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• v.47 no.3
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• pp.365-374
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• 2023

This paper presents a new scheme for constructing locking-free finite elements in thick and thin plates, called Discrete Shear Gap element (DSG), using multiphase material topology optimization for triangular elements of Reissner-Mindlin plates. Besides, common methods are also presented in this article, such as quadrilateral element (Q4) and reduced integration method. Moreover, when the plate gets too thin, the transverse shear-locking problem arises. To avoid that phenomenon, the stabilized discrete shear gap technique is utilized in the DSG3 system stiffness matrix formulation. The accuracy and efficiency of DSG are demonstrated by the numerical examples, and many superior properties are presented, such as being a strong competitor to the common kind of Q4 elements in the static topology optimization and its computed results are confirmed against those derived from the three-node triangular element, and other existing solutions.

• Steel and Composite Structures
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• v.19 no.3
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• pp.661-678
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• 2015

Buckling Restrained Braces (BRB) have been widely used in the construction industry as they utilize the most desirable properties of both constituent materials, i.e., steel and concrete. They present excellent structural qualities such as high load bearing capacity, ductility, energy-absorption capability and good structural fire behaviour. The effects of size and type of filler material in the existed gap at the steel core-concrete interface as well as the element's cross sectional shape, on BRB's fire resistance capacity was investigated in this paper. A nonlinear sequentially-coupled thermal-stress three-dimensional model was presented and validated by experimental results. Variation of the samples was described by three groups containing, the steel cores with the same cross section areas and equal yield strength but different materials (metal and concrete) and sizes for the gap. Responses in terms of temperature distribution, critical temperature, heating elapsed time and contraction level of BRB element were examined. The study showed that the superior fire performance of BRB was obtained by altering the filler material in the gap from metal to concrete as well as by increasing the size of the gap. Also, cylindrical BRB performed better under fire conditions compared to the rectangular cross section.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.3
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• pp.249-257
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• 2015

A fuel assembly consists of fuel rods composed of pellets (UO2) and a cladding tube (Zircaloy). The role of the fuel rods in the reactor is to generate heat by nuclear fission, as well as to retain fission products during operation. A simulation method using a computer program was used to evaluate the safety of the nuclear fuel rods. This computer program has been called the fuel performance code. In the analysis of a light water reactor fuel rod, the gap conductance, which depended on the distance between the pellets and cladding tube, mainly influenced the thermomechanical behavior of the fuel rod. In this work, a 3D gap element was proposed to simulate the thermo-mechanical behavior of the nuclear fuel rod, considering the gap conductance. To implement the proposed 3D gap element, a 3D thermo-mechanical module was also developed using FORTRAN90. The asymmetric characteristics of the nuclear fuel rod, such as the MPS (missing pellet surface) and eccentricity, were simulated to evaluate the proposed 3D gap element.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.2
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• pp.49-54
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• 2002

Most single-Phase brushless DC (BLDC) motors have unequal air gap to eliminate the dead-point where the developed torque value is zero. However this partial increase of the air gap deteriorates the motor characteristics in cogging torque. Thus in this paper a new topology of unequal air gap is proposed to solve this problem. The topology is to use some pairs of equal or unequal air gaps. As a result, it is proved by the finite element analysis and experimental results that the single-Phase BLDC motor with the proposed air gap topology is very effective in reducing the cogging torque.