外文翻譯---沖壓工藝中幾何及內(nèi)圓角對模具應(yīng)力產(chǎn)生的影響

1、附錄 附錄 A 外文文獻(xiàn) 外文文獻(xiàn)Effects of geometry and fillet radius on die stresses in stamping processesAbstract: This paper describes the use of the finite element method to analyze the failure of dies in stamping processes. For th

2、e die analyzed in the present problem, the cracks at different locations can be attributed to a couple of mechanisms. One of them is due to large principal stresses and the other one is due to large shear stresses. A th

3、ree-dimensional model is used to simulate these problems first. The model is then simplified to an axisymmetric problem for analyzing the effects of geometry and fillet radius on die stresses. 2000 Elsevier Science S.A.

4、 All rights reserved.Keywords: Stamping; Metal forming; Finite element method; Die failure1. IntroductionIn metal forming processes, die failure analysis is one of the most important problems. Before the beginning of thi

5、s decade, most research focused on the development of the- oretical and numerical methods. Upper bound techniques [1,2], contact-impact procedures [3] and the finite element method (FEM) [4,5] are the main techniques fo

6、r analyzing stamping problems. With the development of computer technology, the FEM becomes the dominant technique [6-12].Altan and co-workers [13,14] discussed the causes of failure in forging tooling and presented a fa

7、tigue analysis concept that can be applied during process and tool design to analyze the stresses in tools. In these two papers, they used the punching load as the boundary force to analyze the stress states that exist i

8、n the inserts during the forming process and determined the causes of the failures. Based on these concepts, they also gave some suggestions to improve die design.In this paper, linear stress analysis of a three-dimens

9、ional (3D) die model is presented. The stress patterns are then analyzed to explain the causes of the crack initiation. Some suggestions about optimization of the die to reduce the stress concentration are presented. I

10、n order to optimize the design of the die, the effects of geometry and fillet radius are discussed based on a simplified axisymmetric model.2. Problem definitionThis study focuses on the linear elastic stress analysis o

11、f the die in a typical metal forming situation (Fig. 1). The die (Fig. 2) with a half-moon shaped ingot on the top surface is punched down towards the workpiece which is held inside the collar, and the pattern is made

12、onto the workpiece. Cracks were found in the die after repeated operation: (i) when the die punched the workpiece, there is crack initiation between the tip of the moon shaped pattern and one of the edges (Crack I); and

13、 (ii) after repeated punching, there is also a crack at the fillet of the die (Crack II).The present work was carried out with the following objectives: (i) to establish the causes of the crack initiation; and (ii) to

14、study the effects of geometry and fillet According to their analysis, the fatigue failure is due to two factors: (i) when the stress exceeds the yield strength of the die material, a localized plastic zone generally form

15、s during the first load cycle and undergoes plastic cycling during subsequent unloading and reloading, thus microscopic cracks initiate; and (ii) tensile principal stresses cause the microscopic cracks to grow and lead

16、to the subsequent propagation of the cracks.The Von Mises stress distribution is shown in Fig. 5a. Very high stress occur in the half-moon and fillet regions. If the contact pressure keeps increasing, plastic zones will

17、form first in these two regions.Fig. 5b shows the maximum principal stress (SP3) distribution pattern. In order to show the area of Crack I initiation, Fig. 5c provides a zoomed view of the area. It is clear that a tensi

18、le principal stress (SP3) concentration of 25.5 MPa exists between the half-moon pattern and the free edge and is the cause of crack initiation.Since Crack I propagates nearly normal to the 1-2 plane, the direction of t