共查询到20条相似文献,搜索用时 15 毫秒
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分析和论述了板料成形有限元模拟中网格重划技术,研究并建立了板料成形有限元网格重划算法,实现了状态参量在新旧网格中的传递,结合DYNAFORM有限元分析软件,对NUMISHEET’93设定的方盒标准考题进行了模拟,结果证实了该技术的可行性。 相似文献
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Xu Weili Yang Yuying Z. R. Wang Lin Zhongqin 《Journal of Materials Processing Technology》2000,100(1-3)
A new contact judgement method for sheet metal forming simulation is proposed. The method can overcome miss-judgement and error-judgement, and improve numerical stability and computational accuracy effectively. Based on the proposed contact judgement method, a static–implicit FE code is developed. Some typical sheet metal forming processes and the benchmark of NUMISHEET’93 are simulated, and satisfactory results being obtained. 相似文献
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This study is concerned with visioplastic analysis of metal forming processes with help of the R-functions method. The method in conjunction with the flow function and stress function methods is used to construct kinematically admissible velocity fields and statically admissible stress fields for regions with complicated boundary shapes. Application of such fields for approximation of the experimentally obtained information allows to determine mechanically correct strain and stress distribution for steady and non-steady-state problems in axisymmetric and plane-strain metal forming processes. 相似文献
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Sheet-bulk metal forming as a new class of manufacturing processes is one of the possible answers production processes provide to the increasing demands on functional integration into light weight parts made of high strength steel. Research in this field is carried out in several places. The special issue was initiated by the Transregional Collaborative Research Centre 73. It contains newest results from this research initiative as well as international results in the field of sheet-bulk metal forming. 相似文献
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Adam K. Rzepniewski David E. Hardt 《International Journal of Machine Tools and Manufacture》2008,48(5):599
The problem of flexible-tool sheet metal forming and in-process shape control has been confounded by the lack of available measurements during the process. Run-by-run (rbr) control has been developed to achieve feedback control advantages in processes that do not lend themselves to in-process sensing and actuation. While the process cycle time sampling interval limits the performance, rbr can still achieve zero mean error and predictable variance on the output. This paper demonstrates a novel extension of typically single input–single output (SISO) rbr control to the control of discrete-die sheet metal forming which is a multivariable, regionally-coupled process; one where a single input affects a limited region of outputs and a single output is affected by multiple independent inputs. To this end, an easily calibrated, generic plant model is first reviewed. This model, along with others describing regional coupling, proves to be ill-conditioned for even moderately-sized processes. This renders the direct plant inversion used in SISO rbr control impractical. As a result, three controllers that do not rely on inverting the plant are considered: the linear-quadratic regulator (LQR), linear-quadratic Gaussian (LQG), and H-infinity. All three of these controllers are applicable to both square and non-square plants, and they are not limited to the class of plant explicitly considered in this paper. Next, the concept of robustness is introduced by establishing stability limits through structured singular values. All three controllers are experimentally tested on a discrete-die sheet metal forming press. In this stretch forming process, the traditionally monolithic die is divided into many small segments. These segments can then be rearranged to form a new die shape between sheet metal stretching cycles. The proper rearrangement of these inputs in response to output shape error is the goal of the three controllers. Experimental results are in close agreement with theoretical predictions, showing the validity of the modeling and control approaches. 相似文献
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D. H. Kim D. J. Kim D. C. Ko B. M. Kim J. C. Choi 《Metals and Materials International》1998,4(3):548-553
This study shows the correlation between the design methodology of the artificial neural network (ANN) and the statistical design of experiments (DOE) approach and is demonstrated for process design in various metal forming processes. After investigating the effect of each parameter upon the characteristics by the Taguchi method which is one of the DOE, orthogonal array (OA) table and characteristics are applied to ANN as experimental data and then opiimal design parameters are established. Using the rigid plastic FEM, the simulations are performed and the results of ANN are confirmed. This technique requires smaller runs than the conventional method to find the optimal condition of design parameters for the design’s aim. This new technique can be used in a wide range of metal forming process designs. 相似文献
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Development of multistage sheet metal forming analysis method 总被引:1,自引:0,他引:1
The multistep sheet metal forming process for axisymmetric shapes has been modeled employing a simplified finite element analysis
method. The analysis is based on the idea of dividing the deformation history into several steps while applying the total
strain theory of plasticity in each step. An algorithm has been developed which satisfies the potential energy minimization
process at the entire nodal point grouping in each step of the forming process. Although numerical solutions have been obtained
up to a four-step process, there are no inherent limitations in the basic methodology to extend it to any number of steps.
The assumption of proportional loading in each step of forming was carefully examined by comparing the computed principal
strain ratios with those of experimentally observed values. It was found that some regions of the sheet material undergo nonproportional
straining; consequently, a single-step approximation for a multistage forming process may not give a valid result. Sensitivity
of the new model to the number of intermediate steps has also been examined. It is concluded that the new model is a good
approximation of the multistage sheet forming process. 相似文献
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Shichao Ding Paul A. MeehanWilliam J.T. Daniel 《Journal of Materials Processing Technology》2011,211(3):376-381
Millipede forming, a novel sheet metal forming method, has been proposed and developed recently to overcome fundamental limitations in conventional roll forming. For this new method, there are two main aspects: use of an optimal transitional surface and implementation of a method to feed the strip through the transition surface. Achieving the optimal transitional surface involves defining the change of surface shape between a flat strip and a final shaped product conceptualised to the strip's mid-surface, regardless of the strip's thickness.In this paper, one method of implementing a transition surface, Millipede forming, is introduced. A prototype has been built to demonstrate the working principle and can be used to produce some simple profiles, within a short forming length of 200 mm. 相似文献
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将拉延筋模型引入到板料成形动力显式有限元分析中,并以汽车前照灯矩形反光镜为应用实例,对其拉延成形过程进行了模拟。 相似文献
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Sheet metal forming: A review 总被引:1,自引:0,他引:1
William F. Hosford John L. Duncan 《JOM Journal of the Minerals, Metals and Materials Society》1999,51(11):39-44
Developments in the numerical modeling of stamping processes and experimental measurements now make it possible to design
stamping processes using sound engineering principles. This article shows how experimental and theoretical contributions have
led to the concept of a forming window in strain space that identifies the strains that can be developed safely in a sheet
element. It is bounded by failure limits corresponding to localized necking, shear fracture, and wrinkling. A robust stamping
process is one in which the strains in the part lie well within the forming window. The nature of the window and the influence
of material behavior on its shape can be predicted.
Editor’s Note: A hypertext-enhanced version of this article can be found at www.tms.org/pubs/journals/JOM/9911/Hosford-9911.html.
For more information, contact W.F. Hosford, University of Michigan, Department of Materials Science and Engineering, 2300
Hayward Street, Ann Arbor, Michigan 48109-2136; (734) 764-3371; fax (734) 763-4788; e-mail whosford@umich.edu. 相似文献
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Two-step method of forming complex shapes from sheet metal 总被引:2,自引:0,他引:2
Sergey F. Golovashchenko Nicholas M. BessonovAndrey M. Ilinich 《Journal of Materials Processing Technology》2011,211(5):875-885
A two-step method of forming a part and a method of designing a preform shape are being discussed. The part may be formed from lightweight material to an extent that would normally exceed the forming limits of the material if the part were attempted to be formed in one-step conventional stamping die. Critical areas including deep pockets and sharp radius areas of the final part are formed from a preform or intermediate shape part. The first forming step can be conducted by variety of sheet metal forming methods; the preformed blank is further formed in a fluid pressure forming process to a final part shape wherein broad radius areas and pockets of accumulated metal of the preform are formed into deep pockets and sharp corners of the final shape. Electrohydraulic forming technology is employed for the second forming step. 相似文献
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将无网格方法引入三维金属体积成形分析,在给出基于刚塑性流动理论的三维无网格再生核质点方法及其基本理论方程的基础上,为了提高分析系统的通用化和自动化,采用网格法来描述任意形状的三维模具型腔曲面,给出了三维无网格法数值模拟系统中动态接触边界自动处理的非线性接触算法,实现了任意模具形状的三维体积成形过程的无网格法数值模拟。对上模为半球形的三维立方体塑性变形过程进行了数值模拟,并与三维刚塑性有限元体积成形商品软件Deform3D的计算结果作了比较,验证了本文方法的正确性。 相似文献
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A lubricant carrier for metal forming processes is developed. Surfaces with pores of micrometer size for entrapping lubricant are generated by electrochemical deposition of an alloy, consisting of two immiscible metals, of which one metal subsequently is etched away leaving 5 μm layers with a sponge-like structure. The pores will act as lubricant reservoirs during severe forming processes. The deposited microporous layer is evaluated by friction tests in the form of ring compression tests and double cup extrusion tests. Furthermore the anti-seizure properties are investigated by single cup extrusion at high reduction and excessive stroke comparing with conventionally lubrication using phosphate coating and soap. 相似文献
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Raja Srinivasan Anil Chaudhary Sc.D. 《JOM Journal of the Minerals, Metals and Materials Society》1990,42(2):22-23
The central idea behind a numerical approach for parameter tolerance design is the concept that multiple numerical process simulations can be used in accordance with the Taguchi orthogonal experiment arrays to perform parameter sensitivity analysis and for tolerance design using a quality loss function. The quality loss function is analytically defined using a novel material modeling technique based upon the second law of thermodynamics. 相似文献
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A new upper-bound elemental technique (UBET) is proposed to improve the ineffectiveness of UBET for solving forging problems that are geometrically complex or need a forming simulation for predicting the profile of free boundary. This method combines the advantages of the stream function and the finite element method (FEM); specifically, the curve fitting property of FEM and the fluid incompressibility of the stream function. The formulated optimal design problems with constrained conditions are solved by the flexible tolerance method. Three forming problems (ring upsetting, closed-die, and backward-extrusion forging) are used to illustrate this method: the results of ring upsetting show a good ability of simulating for predicting the forming profile of a free boundary; the closed-die forging produces a lower upper-bound solution than UBET; and backward-extrusion forging demonstrates the flexible curve fitting property for a complex geometric boundary. 相似文献