基于Lemaitre模型的辊式冲裁工艺断面质量分析

为了准确表征材料变形中逐渐劣化的过程,引入考虑损伤与裂纹萌发的弹塑性本构模型.基于Abaqus/Explicit的二次开发接口,编写耦合Lemaitre损伤模型的用户子程序,根据算例验证其可靠性.通过反复加载-卸载拉伸试验并利用弹性模量变化法来获得损伤参数值.建立辊式冲裁工艺有限元模型,应用Lemaitre损伤模型来预测断面质量,并进行试验验证.分析冲裁间隙、模具磨损与板厚等工艺参数对断面质量、冲裁力及扭矩的影响.结果表明:前刃口断面质量总体上要好于后刃口,但光亮带具有一定的倾角;塌角区会随冲裁间隙增加而增大;模具磨损程度增加会导致毛刺急剧增大;最大冲裁力与扭矩会随着板厚的增大而增大.

Analysis of sheared edge quality in rotary blanking process based on Lemaitre damage model

To accurately describe the material degradation process from elastoplastic deformation to final rupture, an elastoplastic constitutive model was established to feature damage and crack initiation. A user-defined material subroutine VUMAT was developed, based on the Abaqus/ Explicit platform, and its reliability was validated with an example. The damage parameter values were deter-mined in cyclic loading-unloading tensile tests, using the Young's modulus weakening method. To predict the sheared edge quality, a finite element model of rotary blanking coupling with a Lemaitre damage model was built and the numerical results were compared with experimental results. The influences of blanking clearance, die wear and sheet metal thickness on the sheared edge quality, blanking force and torque were investigated. The results show that the sheared edge quality of the leading cutting edge is generally better than that of the trailing cutting edge, but the burnish depth of the leading cutting edge tilts at an angle. The rollover is larger, as is the die clearance. There is an extreme increase in the burr height when the degree of die wear is higher. The highest blanking force and torque values increase as the sheet metal thickness increases.