外文翻譯--一種能反映深拉深過程中加載和卸載影響的摩擦型模（英文）

1、A friction model for loading and reloading effects in deep drawing processes$D.K. Karupannasamy a,b,n, J. Hol a,c, M.B. de Rooij b, T. Meinders c, D.J. Schipper ba Materials innovation institute (M2i), P.O. box 5008, 260

2、0 GA Delft, The Netherlands b University of Twente, Faculty of Engineering Technology, Laboratory for Surface Technology and Tribology, P.O. box 217, 7500 AE Enschede The Netherlands c University of Twente, Faculty of En

3、gineering Technology, Nonlinear solid mechanics, P.O. box 217, 7500 AE Enschede, The Netherlandsa r t i c l e i n f oArticle history:Received 3 January 2014Received in revised form8 June 2014Accepted 9 June 2014 Availabl

4、e online 18 June 2014Keywords:Friction modelDeep drawing processAsperity flatteningPloughingBoundary lubricationa b s t r a c tDeep drawing is one of the most widely-used forming processes to manufacture automotive body

5、partsfrom sheet metal. In order to simulate deep drawing processes, a finite element (FE) method was used topredict formability. The accuracy of the FE simulation depends on the material models, numericaltechniques, and

6、contact algorithms. Despite the fact that the contact conditions between the tool andsheet material influences the coefficient of friction in forming processes, the coefficient of friction isoften treated as a constant C

7、oulomb friction coefficient in FE simulations. However, a friction modelbased on local contact conditions and surface topography is required to improve forming predictability.There is growing interest in developing conta

8、ct models to predict the nature of friction conditions foruse in FE calculations. In deep drawing processes, the sliding contact predominantly occurs in the blankholder region between the tool and sheet material. The con

9、tact pressure in the blank holder is non-uniform due to bending and material compression which vary depending on tool geometry. The sheetmetal surface is subjected to repeated contact during sliding, which in turn affect

10、s the local frictionconditions. The objective of this paper is to develop a sliding friction model for mixed modes of surfacedeformation. The deterministic approach used in the current model includes the roughness of bot

11、h thesheet material and the tool. The sheet material is subject to an asperity flattening process. Further, thetool surface indents into the sheet material under normal loading. The geometry of the asperities ischaracter

12、ized by an elliptical paraboloid shape to better calculate the load-dependence of friction. Themodel has been compared with data from experiments using a rotational friction tester under multipleloading conditions.fax: &

13、#254;31 534894784.E-mail addresses: k.dineshkumar@yahoo.co.in,d.karupannasamy@m2i.nl (D.K. Karupannasamy).Wear 318 (2014) 27–39elastic–plastic contact is described by Masen et al., [23] to calculate the wear process. The

14、 coefficient of friction is calculated based on the ploughing of the tool asperities as described by Karupannasamy et al., [13] for two rough surfaces in contact using the model of [23].1.3. Asperity characterizationThe

15、surface is represented in a height matrix of pixels. As the contact load is increased, the surface separation reduces. For a known surface separation, the contact patches are located within the height matrix. The contact

16、 patches are identified by means of connected pixels. After the contact patches are identified, they were characterized as elliptical paraboloids using the volume and area of the contact patch as given by de Rooij et al.

17、 [24]. This gives a better control for the description of the asperity compared to the conical or spherical shape according to [14,23,24]. The base area of the contact patch is described using an ellipse with a semi-majo

18、rand semi-minor radii, a and b and the orientation of the ellipse with respect to sliding direction, φ as shown in Fig. 2. The elliptical paraboloid asperity is characterized with radii in the major and minor axis direct

19、ions as denoted by Rx and Ry.2. Single asperity deformation modelAn asperity which is in contact undergoes three different modes of deformation with increasing load, i.e. elastic, elastic–plastic and plastic deformation.

20、 When the load is increased to a critical load which is beyond the elastic regime, the onset of plasticity occurs. The plasticity occurs beneath the surface. While unloading the asperity, a part of the deformation zone r

21、emains plastic and the rest of the deformation recovers. The asperity geometry changes due to the plastic deformation. A finite element simulation is shown by Shankar and Mayuram [25] for the deformation of hemispherical

22、 asperity with a rigid flat. Initially, a plastic deformation zone starts in a smallDeformed Workpiece surface Friction model W/FN Boundary layers FW Workpiece Tool Identification of contact patches and mapping of too

23、l surface FN Asperity characterization Fig. 2. Contact occurring between tool and sheet metal surfaces in deep drawing processes.Contact pressure from a FE simulation of a cup drawing process 1 2 3 Fig. 1. Contact cond