• 대한용접접합학회:학술대회논문집
• /
• 대한용접접합학회 2003년도 춘계학술발표대회 개요집
• /
• pp.210-212
• /
• 2003

Finite element analysis of welding processes, which entail phase evolution, heat transfer and deformation, is considered in this paper. Attention focuses on numerical implementation of the thermo-elastic-plastic constitutive equation proposed by Leblond et al in consideration of the transformation plasticity. Based upon the multiplicative decomposition of deformation gradient, hyperelastic formulation is employed for efficient numerical integration, and the algorithmic consistent moduli for elastic-plastic deformations including transformation plasticity are obtained in the closed form. The convergence behavior of the present implementation is demonstrated via a couple of numerical example.

• Steel and Composite Structures
• /
• 제18권5호
• /
• pp.1083-1101
• /
• 2015

Previous theoretical equations for the shear capacity of steel beam to concrete filled steel tube (CFT) column connections vary in the assumptions for the shear deformation mechanisms and adopt different equations for calculating shear strength of each component (steel tube webs, steel tube flanges, diaphragms, and concrete etc.); thus result in different equations for calculating shear strength of the joint. Besides, shear force-deformation relations of the joint, needed for estimating building drift, are not well developed at the present. This paper compares previously proposed equations for joint shear capacity, discusses the shear deformation mechanism of the joint, and suggests recommendations for obtaining more accurate predictions. Finite element analyses of internal diaphragm connections to CFT columns were carried out in ABAQUS. ABAQUS results and theoretical estimations of the shear capacities were then used to calibrate rotational springs in joint elements in OpenSEES simulating the shear deformation behavior of the joint. The ABAQUS and OpenSEES results were validated with experimental results available. Results show that: (1) shear deformation of the steel tube dominates the deformation of the joint; while the thickness of the diaphragms has a negligible effect; (2) in OpenSEES simulation, the joint behavior is highly dependent on the yielding strength given to the rotational spring; and (3) axial force ratio has a significant effect on the joint deformation of the specimen analyzed. Finally, modified joint shear force-deformation relations are proposed based on previous theory.

• 대한조선학회논문집
• /
• 제44권1호
• /
• pp.32-39
• /
• 2007

A three-dimensional finite element model has been developed to simulate the MIG P/S welding process of two aluminum plates. The finite element calculations are performed using ANSYS finite element code, which takes into account the thermal and mechanical non-linear material properties. The results of finite element analysis compared with those of experiment to show its validity in view of distortions. Parametric studies are carried out on the validated model to assess the effects of various factors on the final residual distortion. Large deformations, temperature dependent material properties are included in the model. Finally, the formulas of fitting curves of angular distortion transverse shrinkage, and longitudinal shrinkage have been proposed.

• Design & Manufacturing
• /
• 제7권1호
• /
• pp.34-39
• /
• 2013

The finite element method(FEM) presents some limitations when the mesh becomes highly distorted. For analysis of metal forming processes with large deformation, the conventional finite element method usually requires several remeshing operations due to severe mesh distortion. The new computational method developed in the recent years, usually designated by meshfree method, offers an attractive approach to avoid those time-consuming remeshing efforts. This new method uses a set of points to represent the problem domain with no need of an additional mesh. Also this new generation of computational method provides a higher rate of convergence than that of the conventional finite element methods. One of the promising applications of meshfree methods is the adaptive refinement for problems having multi-scale nature. In this study, an adaptive node generation procedure is proposed and also to illustrate the efficiency of proposed method, several numerical examples are presented.

• 소성∙가공
• /
• 제6권5호
• /
• pp.408-415
• /
• 1997

The backward tracing scheme of the finite element analysis, which is counted to be unique and useful for process design in metal forming, has been developed and applied successfully in industry to several metal forming processes. Here the backward tracing scheme is implemented for process design of three-dimensional plastic deformation in metal forming, and it is applied to a precision coining process. The contact problem between the die and workpiece has been treated carefully during backward tracing simulation in three-dimensional deformation. The results confirm that the application of the developed program implemented with backward tracing scheme of the rigid plastic finite element leads to a reasonable initial piercing hole configuration. It is concluded that three-dimensional extension of the scheme appears to be successful for industrial applications.

• Steel and Composite Structures
• /
• 제35권1호
• /
• pp.43-59
• /
• 2020

In this study, free vibration analysis of laminated composite parabolic thick plate frames by using finite element method is introduced. Governing equations of an eigenvalue problem are obtained from First Order Shear Deformation Theory (FSDT). Finite element method is employed to obtain natural frequency values from the governing differential equations. The frames consist of two flat square plates and one singly curved plate. Parameters like radii of curvature, aspect ratio, ply orientation and boundary conditions are investigated to understand their effect on dynamic behavior of such a structure. In addition, multi-bay structures of such geometry with different stacking order are also taken into account. The composite frame structures are also modeled and simulated via ANSYS to verify the accuracy of the present study.

• 소성∙가공
• /
• 제25권5호
• /
• pp.325-331
• /
• 2016

In this paper, a three-dimensional part model is constructed for the finite element analysis of hemming models where hemming defects frequently occur. The roller path is modeled as the boundary condition with the one-dimensional beam element and the revolute joint model. With the constructed part model and the roller movement, a finite element analysis has been pursued in order to identify the hemming load and hemming defects such as wrinkling in the flange region. The analysis result shows that the maximum hemming load occurs in the intake situation while oscillatory behavior of the load is found especially when hemming the curved model because of wrinkle generation. This paper compares the amplitude and the period of wrinkle between the analysis result and the experiment, which shows good agreement with each other.

• 전자공학회논문지B
• /
• 제31B권6호
• /
• pp.81-90
• /
• 1994

Finite element analysis is performed for transient thermal deformation of a shadow mask inside the Braun tube and the landing shift or mislanding of the electronic beam is calclated. The shadow mask has numerous slits through which the electronic beams are guided to land on the designed phosphor. Its thermal deformations therefore cause the mislanding of the electronic beam and result in decolorization of a screen. For realistic finite element analysis, firstly the effective thermal conductivity and the effective elastric modulus are calculated, and the shadow mask is modeled as shell without slits. Next the nonlinear finite element formulation is developed for transient heat transfer on the shadow mask, wherein thermal radiation is a major heat transfer mechanism. Analysis of the resulting thermoelastic deformations is followed, from which the mislanding of the electronic beam is obtained. The present finite element scheme may be efficiently used for thermal deformation design of a shadow mask.

• 대한기계학회논문집A
• /
• 제27권9호
• /
• pp.1539-1545
• /
• 2003

A lot of researches have been performed on the equal channel angular pressing (ECAP) which produces ultra-fine grains. Along with the experiments, the finite element method has been widely employed to investigate the deformation behavior of specimen during ECAP and the effects of process parameters of ECAP. In this paper, pure-Zirconium is considered for ECAP process by using three-dimensional finite element analysis. The results have been compared with those of previous two-dimensional analysis and with the experimental results

• 한국정밀공학회지
• /
• 제10권4호
• /
• pp.206-215
• /
• 1993

The finite element method is applied to analyze the mechanism of metal cutting, especially micro metal cutting. This paper introduces some effects, such as constitutive deformation laws of workpiece material, friction of tool-chip contact interfaces, tool rake angle and also simulate the cutting process, chip formation and geometry, tool-chip contact, reaction force of tool. Under the usual plane strain assumption, quasi-static analysis were performed with variation of tool-chip interface friction coefficients and tool rake angles. In this analysis, cutting speed, cutting depth set to 8m/sec, 0.02mm, respectively. Some cutting parameters are affected to cutting force, plastic deformation of chip, shear plane angle, chip thickness and tool-chip contact length and reaction forces on tool. Several aspects of the metal cutting process predicted by the finite element analysis provide information about tool shape design and optimal cutting conditions.