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Chen J.,Beijing Institute of Technology | Daxin E.,Beijing Institute of Technology | Zhang J.,China Automotive Engineering Research Institute Co.
International Journal of Advanced Manufacturing Technology | Year: 2013

Process parameters, such as clearance, friction, boosting displacement, bending velocity, and centerline radius/tube diameter ratio, have a significant and complicated influence on wrinkling of circular tubes during rotary draw bending process. To explore the effects of these parameters on the wrinkling, a 3D elastic-plastic finite element (FE) model based on eta/DYNAFORM has been built and validated by experiments. Then, relevant simulation and analysis of the process have been performed. The results show that: (1) the wrinkling increases with the accretion of the clearance. A reasonable clearance of mold groove (less than 0.2 mm) can alleviate the severity of the wrinkling; (2) when the boosting velocity of the pressure die is larger than or equal to the linear velocity of the bend die in the X-axis direction, the wrinkling relieves as the friction between the pressure die and the tube decreases; conversely, when the boosting velocity is smaller than the linear velocity, the wrinkling reduces with the increase of the friction between the two contacted components; (3) the wrinkling is negatively correlated with the centerline radius/tube diameter ratio and positively correlated with the bending velocity of the bend die; and (4) the boosting displacement of the pressure die dominates the direction of frictional force exerted by the pressure die in the bending process. The wrinkling tendency becomes more obvious as the displacement increases. © 2013 Springer-Verlag London.


Zhu C.-C.,Chongqing University | Luo J.-Y.,Chongqing University | Luo J.-Y.,China Automotive Engineering Research Institute Co.
Journal of Central South University of Technology (English Edition) | Year: 2012

Numerical simulation combined with experimental test was carried out to analyze the pre-stretching process of the 7075 aluminum alloy sheet, from which the stress variation curves and residual stress of aluminum alloy sheet in different stretch rates were obtained. The results show that the residual stress in length direction is released after unloading the stretch force, while the residual stress in width direction is released during the stretching process. The study of residual stress elimination is beneficial for optimizing stretch rate on the basis of residual stress distribution law. By comparing the variation principle of residual stress in length direction, the size range of three deformation areas and elimination percentage of residual stress were obtained. The residual stresses of clamping area and transition area are not eliminated effectively, so sawing quantity should be the sum of both the areas. The elimination rate of residual stress in even deformation area could reach 90% after choosing a proper stretch rate, which is verified by both simulation and experiment. © 2012 Central South University Press and Springer-Verlag Berlin Heidelberg.


Yao L.Y.,China Automotive Engineering Research Institute Co. | Yu D.J.,Hunan University | Cui W.Y.,Hunan University | Zhou J.W.,China Automotive Engineering Research Institute Co.
Noise Control Engineering Journal | Year: 2012

This paper presents a finite element-least square point interpolation method (FELSPIM) for solving 2D acoustic problem by synthesizing the attractive features of finite element and least-square point interpolation shape functions using the concepts of partition of unity (PU) methods. In the present method, the acoustic domain is discretized using quadrilateral element, and the shape functions of the quadrilateral element are used for PU and the least-square point interpolation method (LSPIM) for local approximation. This enables the proposed method to inherit the compatibility properties of finite element method and the quadratic polynomial completeness properties of meshfree methods, so that the finite element-least-square point interpolation method (FE-LSPIM) will greatly reduce the numerical dispersion error because the numerical dispersion error is essentially caused by the "overly-stiff" nature of the FEM model. Numerical results for benchmark problems show that, the FE-LSPIM achieves more accurate results and higher convergence rates as compared with the corresponding finite elements and Element-free Galerkin method (EFGM), especially for high wave number and irregular meshes. © 2012 Institute of Noise Control Engineering.


Yao L.Y.,China Automotive Engineering Research Institute Co. | Yu D.J.,Hunan University | Zhou J.W.,China Automotive Engineering Research Institute Co.
Applied Acoustics | Year: 2012

This paper addresses the cell-based smoothed radial point interpolation method (CS-RPIM) for 2D acoustic problem. In present method, the acoustic domain is discretized using triangular background cells, and each cell is further divided into several smoothing cells and then the cell-based gradient smoothing operation is implemented through the smoothing cells. The pressure field function is approximated using RPIM shape functions. Supporting node selection for shape function construction uses the T2L-scheme associated with edges of the background cells. The system equations are derived using the smoothed Galerkin weak form, and the essential boundary conditions are imposed directly as in the finite element method (FEM). The cell-based gradient smoothing operation provides proper softening effect, makes the CS-RPIM model much softer than the "overly-stiff" FEM model and hence significantly reduces the numerical dispersion error. Numerical results show that the CS-RPIM achieves more accurate results and higher convergence rates as compared with the corresponding finite elements © 2012 Elsevier Ltd. All rights reserved.


Zhou J.,China Automotive Engineering Research Institute Co. | Zhou J.,Chongqing Automotive Lightweight Engineering Research Center | Wan X.,China Automotive Engineering Research Institute Co. | Wan X.,Chongqing Automotive Lightweight Engineering Research Center | And 2 more authors.
Materials Today: Proceedings | Year: 2015

The present paper deal with aluminium alloys and their manufacturing technologies (stamping, extrusion, casting, etc.) applied on vehicles on EuroCarBody from 2009 to 2013 through presentations and benchmark data. The using percentage of aluminium alloy on body in white (BIW) are summarized and analyzed. The number of vehicles using aluminium alloy are increasing from 2009 to 2013 on some kind of vehicles. More and more new technologies are adopted by using aluminium alloys to manufacture parts, With the developing of the automotive industry, more and more aluminium alloys parts will be applied on vehicles in the future. EuroCarBody is an important forum for defining and discussing the state of the art in modern series car body engineering. © 2015 Elsevier Ltd.

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