| Automotive stamping panels generally are large size and complex structure, often as a result of unreasonable die design or stamping process in a variety of forming defects (such as fracture, wrinkle, springback). The stamping forming analysis CAE technology is the multitudinous discipline intercrossing high-tech of metal plasticity processing, computation mechanics and mathematics, the electronic information and the computer technology, the new material, the automobile body project and the machine manufacture and so on. Adoption of computer-assisted stamping forming analysis, through of forming process's quantitative numerical simulation, optimization of die structure, surface design, shorten the die test cycle, thereby reducing the vehicle cost, and enhance market competition.Stamping edge fracture defect of sheet metal has been one of mainly factor to effect production stability control and sheet metal products quality. Edge fracture occurs on the sheet metal forming, the concave side (or straight edge) where the major stress (σ1) axe is approximately tangential to the stamping edge, and its value reached a certain level. Now existent FEM (Finite Element Method) simulation software can mostly indicate fracture defect of sheet metal stamping. For example, in this field, Dynaform,Autoform and so on have done quite well job. But there are mostly two situations, one is flange operation, the other is automotive panel with larger hole, because of neglecting the factor of along sheared edge defects leading deformation capacity to decrease dramatically, it is difficult to accurately indicate whether it will happen edge fracture. To this issue, as the basis of Dr.Yanwu Xu's forming theory of edge fracture, in the Institute of Automobile Body and Die Engineering in Jilin university KMAS (King Mesh Analysis System) software development platform——COMX, developed edge fracture analysis software module.Edge fracture's typical condition is the stretch flanging, the paper as the concave flange in outside edge as an example, studied edge fracture mechanism. After stress-strain state analysis, found that the first major strainε1 is much larger than the second major strainε2,and the third major strainε3. There are little difference between the calculated equivalent strainεe and the first major strainε1. Therefore, edge fracture state can be similar to single tensile state,ε1 replacesεe to determine whether the edge fracture occurs. In flanging process, if sheet metal's concave side (or straight edge) where the major stress (σ1) is approximately tangential to the stamping edge, fracture will occur on that the value is far from attaining the material yield limit. The study found that sheared edge's work-hardening zone,burrs and micro-cracks defects leading deformation capacity to decrease dramatically, and the defects produced in the separation process which can not be indispensable on each stamping forming. So, all the stamping edge had sheared defects. In this paper, to Dr. Yanwu Xu the largest deformation capacity to characterization of properties of metal materials, with the remainder of deformability as formability index of the edge fracture analysis. Materials largest deformation capacity is the equivalent strain of the such material deformability necking happen. Because sheared edge's deformation due to sheet metal edge state, work-hardening zone and micro-cracks are difficult to be quantified, so the burr relative height is on behalf of the sheared edge state to analyze the deformability of sheet metal edge. Author's Group to do a special experiment, to quantify the relationship between the maximum deformation and burr relative height. This paper is based on the experimental result, got the largest capacity DCe of sheared edge. RCMDe is the difference between DCe and strain near the sheared side. Comparing RCMDe and safety factorΔRCMD, if RCMDe≥?RCMD, sheared edge is safe, edge will not spilt, If RCMDe |
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