• Title, Summary, Keyword: Finite Element Contact Analysis

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Contact Heat Transfer Coefficient for Finite Element Analysis in Warm Forging Processes (온간단조 공정의 계면열전달계수)

  • Kang J.H.;Ko B.H.;Jae J.S.;Kang S.S.
    • Transactions of Materials Processing
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    • v.15 no.3
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    • pp.183-188
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    • 2006
  • Heat transfer coefficients have great influence on finite element analysis results in elevated temperature forging processes. Experimentally calculated contact heat transfer coefficient is not suitable for one-time finite element analysis because analyzed temperature will be appeared to be too low. To get contact heat transfer coefficient for one-time finite element analysis, tool temperature in operation was measured with thermocouple and repeated finite element analysis was performed with experimentally calculated contact and cooling heat transfer coefficient. Surface temperature of active tool was obtained comparing measurement and analysis results. Contact heat transfer coefficient for one-time finite element analysis was achieved analyzing surface temperature between repeated finite element analysis and one-time finite element analysis results.

Finite Element Analysis for Frictional Contact Problems of Axisymmetric Deforming Bodies (축대칭 변형체의 마찰 접촉문제에 관한 유한요소 해석)

  • 장동환;조승한;황병복
    • Transactions of Materials Processing
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    • v.12 no.1
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    • pp.26-33
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    • 2003
  • This paper is concerned with the numerical analysis of frictional contact problems in axisymmetric bodies using the rigid-plastic finite element method. A contact finite element method, based on a penalty function, are derived from variational formulations. The contact boundary condition between two deformable bodies is prescribed by the proposed algorithm. The program which can handle frictional contact problem is developed by using pre-existing rigid-plastic finite element code. Some examples used in this paper illustrate the effectiveness of the proposed formulations and algorithms. Efforts focus on the deformation patterns, contact force, and velocity gradient through the various simulations.

Finite Element Analysis of Adhesive Contact of Torus-Shaped Bumps (토러스형 돌기의 흡착접촉 유한요소해석)

  • 조성산;양승민
    • Tribology and Lubricants
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    • v.18 no.4
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    • pp.249-254
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    • 2002
  • Adhesive contact characteristics of torus-shaped bumps were analyzed using the finite element technique considering the adhesive force. Analyses focused on the effect of rim and bump radii on the adhesive contact behavior such as the jump-to-contact behavior, adhesion hysteresis, pull-off forces, contact region and pressure, and surface and subsurface stresses. Analysis results in the absence of adhesive force were also included to examine the effect of adhesive force. The applicability of torus-shaped bumps to the MEMS structure for reduction of friction is discussed.

Searching Algorithm for Finite Element Analysis of 2-D Contact Problems (2차원 접촉문제의 유한요소 해석을 위한 탐색알고리즘)

  • 장동환;최호준;고병두;조승한;황병복
    • Journal of the Korean Society for Precision Engineering
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    • v.20 no.12
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    • pp.148-158
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    • 2003
  • In this paper, efficient and accurate contact search algorithm is proposed for the contact problems by the finite element method. A slave node and a maser contact segment is defined using the side of a finite element on the contact surface. The specific goal is to develop techniques of reducing the nonsmoothness of the contact interactions arising from the finite element discretization of the contact surface. Contact detection is accomplished by monitoring the territory of the slave nodes throughout the calculation for possible penetration of a master surface. To establish the validity of the proposed algorithm, some different process and geometries examples were simulated. Efforts are focused on the error rate that is based on the penetrated area through the simulations fur large deformation with contact surface between deformable bodies. A proposed algorithm offers improvements in contact detection from the simulation results.

Finite Element Analysis of Pivot Stiffness for Tilting Pad Bearings and Comparison to Hertzian Contact Model Calculations (유한 요소 해석을 통해 계산된 틸팅 패드 베어링의 피봇 강성과 Hertzian 접촉 모델 해석 결과 비교)

  • Lee, Tae Won;Kim, Tae Ho
    • Tribology and Lubricants
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    • v.30 no.4
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    • pp.205-211
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    • 2014
  • Recent studies emphasize the importance of pivot stiffness in the analysis of tilting pad bearings (TPBs). The present paper develops a finite element model of the pad pivot and compares the predicted pivot stiffness to the results of Hertzian contact model calculations. Specifically, a finite element analysis generates tetrahedral mesh models with ~40,000 nodes for a ball-socket pivot and ~50,000 nodes for a rocker-back pivot. These models assume a frictionless boundary condition in the contact area. Increasing the applied loads on the pad in conjunction with increasing time steps ensures rapid convergence during the nonlinear numerical analysis. Predictions are performed using the developed finite element model for increasing the differential diameters between the pad pivot (or ball) and the bearing housing (or socket). The predictions show that the pivot contact area increases with decreasing differential diameters and increasing applied loads. Further, the maximum deformation occurring at the pivot center increases with increasing differential diameters and increasing applied loads. The pivot stiffness increases nonlinearly with decreasing differential diameters and increasing applied loads. Comparisons of results of the developed finite element model to those of Hertzian contact model calculations assuming a small contact area show that the latter model underestimates the pivot stiffnesses predicted by the finite element models of the ball-socket and rocker-back pivots, particularly for small differential diameters. This result implies the need for cautionduring the design of pivot stiffness by the Hertzian contact model.

Finite Element Analysis of Multiple Subsurface Cracks in Half-space Due to Sliding Contact

  • Lee, Sang Yun;Kim, Seock Sam
    • KSTLE International Journal
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    • v.2 no.1
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    • pp.12-16
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    • 2001
  • A finite element analysis of crack propagation in a half-space due to sliding contact was performed. The sliding contact was simulated by a rigid asperity moving across the surface of an elastic half-surface containing single and multiple cracks. Single, coplanar, and parallel cracks were modeled to investigate the interaction effects on the crack growth in contact fatigue. The analysis was based on linear elastic fracture mechanics and the stress intensity factor concept. The crack propagation direction was predicted based on the maximum range of the shear and tensile stress intensity factors.

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Biomechanical Analysis of the Shelf Operation for Dysplastic Hip Joint by Finite Element Analysis (유한요소해석을 이용한 이형성 고관절의 선반형성술에 대한 생체역학 해석)

  • Park W.M.;Kim Y.H.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.519-520
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    • 2006
  • The aim of this study was biomechanical analysis of shelf operation in patients with dysplastic hip joint by finite element contact analysis. Two dimensional CT images were used to construct the finite element models to analyze the contact pressure, and the 3D expansion of the Ninomiya's method was used in the calculation of the resultant force in the hip joint. The surgery recovered the center-edge angles to the normal anatomical range and increased the contact areas in two patients. The maximum contact pressures and von-mises stresses were decreased. The present study provides the biomechanical guideline of optimal surgical parameters to maximize the surgical efficiency and the clinical outcomes in dysplastic hip joint using the shelf operation.

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Finite element generalized tooth contact analysis of double circular arc helical gears

  • Qu, Wentao;Peng, Xiongqi;Zhao, Ning;Guo, Hui
    • Structural Engineering and Mechanics
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    • v.43 no.4
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    • pp.439-448
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    • 2012
  • This paper investigates the load sharing of double circular arc helical gears considering the influence of assembly errors. Based on a load sharing formulae, a three-dimensional finite element tooth contact analysis (TCA) is implemented with commercial software package ANSYS. The finite element grid for the double circular arc gear contact model is automatically generated by using the APDL (ANSYS Parameter Design Language) embedded in ANSYS. The realistic rotation of gears is achieved by using a coupling degree-of-freedom method. Numerical simulations are carried out to exemplify the proposed approach. The distribution of contact stress and bending stress under specific loading conditions are computed and compared with those obtained from Hertz contact theory and empirical formulae to demonstrate the efficiency of the proposed load sharing calculation formulae and TCA approach.

Metal forming analysis using meshfree-enriched finite element method and mortar contact algorithm

  • Hu, Wei;Wu, C.T.
    • Interaction and multiscale mechanics
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    • v.6 no.2
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    • pp.237-255
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    • 2013
  • In this paper, a meshfree-enriched finite element method (ME-FEM) is introduced for the large deformation analysis of nonlinear path-dependent problems involving contact. In linear ME-FEM, the element formulation is established by introducing a meshfree convex approximation into the linear triangular element in 2D and linear tetrahedron element in 3D along with an enriched meshfree node. In nonlinear formulation, the area-weighted smoothing scheme for deformation gradient is then developed in conjunction with the meshfree-enriched element interpolation functions to yield a discrete divergence-free property at the integration points, which is essential to enhance the stress calculation in the stage of plastic deformation. A modified variational formulation using the smoothed deformation gradient is developed for path-dependent material analysis. In the industrial metal forming problems, the mortar contact algorithm is implemented in the explicit formulation. Since the meshfree-enriched element shape functions are constructed using the meshfree convex approximation, they pose the desired Kronecker-delta property at the element edge thus requires no special treatments in the enforcement of essential boundary condition as well as the contact conditions. As a result, this approach can be easily incorporated into a conventional displacement-based finite element code. Two elasto-plastic problems are studied and the numerical results indicated that ME-FEM is capable of delivering a volumetric locking-free and pressure oscillation-free solutions for the large deformation problems in metal forming analysis.

Fretting Wear Simulation of Press-Fitted Shaft with Finite Element Analysis and Influence Function Method (유한요소해석과 영향함수법을 이용한 압입축의 프레팅 마모해석)

  • Lee, Dong-Hyong;Kwon, Seok-Jin;Choi, Jae-Boong;Kim, Young-Jin
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.32 no.1
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    • pp.54-62
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    • 2008
  • In this paper the fretting wear of press-fitted specimens subjected to a cyclic bending load was simulated using finite element analysis and numerical method. The amount of microslip and contact variable at press-fitted and bending load condition in a press-fitted shaft was analysed by applying finite element method. With the finite element analysis result, a numerical approach was applied to predict fretting wear based on modified Archard's equation and updating the change of contact pressure caused by local wear with influence function method. The predicted wear profiles of press-fitted specimens at the contact edge were compared with the experimental results obtained by rotating bending fatigue tests. It is shown that the depth of fretting wear by repeated slip between shaft and boss reaches the maximum value at the contact edge. The initial surface profile is continuously changed by the wear at the contact edge, and then the corresponding contact variables are redistributed. The work establishes a basis for numerical simulation of fretting wear on press fits.