航空学报 > 2011, Vol. 32 Issue (7): 1309-1317   doi: CNKI:11-1929/V.20101228.1334.002

一种改进的Lemaitre韧性断裂准则及其在旋压成形中的应用

吴卷, 詹梅, 蒋华兵, 陈飞, 杨合   

  1. 西北工业大学 凝固技术国家重点实验室, 陕西 西安 710072
  • 收稿日期:2010-10-28 修回日期:2010-11-19 出版日期:2011-07-25 发布日期:2011-07-23
  • 作者简介:吴卷(1985- ) 女, 硕士研究生。 主要研究方向: 先进塑性加工技术与计算机仿真的研究。 Tel:029-88460212-805 E-mail: wj1372169@163.com 詹梅(1972- ) 女, 博士, 教授, 博士生导师。 主要研究方向: 材料加工工程中的先进塑性成形技术、 计算机模拟仿真及智能化的研究。 Tel: 029-88460212-805 E-mail: zhanmei@nwpu.edu.cn
  • 基金资助:

    国家"863"计划(2008AA04Z122)

A Modified Lemaitre Ductile Fracture Criterion and Its Application to Spinning Forming

WU Juan, ZHAN Mei, JIANG Huabing, CHEN Fei, YANG He   

  1. State Key Laboratory of Solidification Processing, Northwestern Ploytechnical University, Xi’an 710072, China
  • Received:2010-10-28 Revised:2010-11-19 Online:2011-07-25 Published:2011-07-23

摘要: 采用Lemaitre韧性断裂准则与有限元模拟相结合来预测材料在塑性成形过程中的开裂是广泛应用的一种方法,其中的Lemaitre准则是以损伤值与塑性应变呈线性关系为基础的,而实际一些材料的损伤值与塑性应变间却是非线性的。为此,本文将原Lemaitre准则中反映损伤值与塑性应变间的线性关系修正为非线性关系,得到了改进的Lemaitre准则。对比采用改进前后的Lemaitre准则对锥形件旋压和分形旋压开裂的预测结果表明,改进后的Lemaitre准则的预测结果更符合实际。采用改进后的Lemaitre准则在旋压成形中进行应用,获得了偏离率和芯模转速对锥形件旋压过程中损伤值分布和变化的影响。结果表明:零偏离时的损伤值较小,分布也较均匀;大的负、正偏离率下工件的损伤发生的区域不同,在大的负偏离率下,损伤主要发生在工件的顶部大拉应力作用区和旋轮作用下的变形区,在大的正偏离率下,旋轮和起皱后凸缘的干涉作用导致损伤主要分布在凸缘处;当进给比一定时,芯模转速越小,损伤发展越缓慢,越有利于工件的成形。

关键词: 韧性断裂, Lemaitre准则, 非线性, 锥形件旋压, 分形旋压, 损伤

Abstract: Combining the Lemaitre ductile fracture criterion with finite element simulation is a method widely used in predicting the cracking of a workpiece in plastic forming. In the Lemaitre criterion, the relationship between the damage value and plastic strain is supposed to be linear, which is not the case for some materials that exhibit a nonlinear relationship. In this study, the Lemaitre criterion is modified by substituting linearity for non-linearity between the damage value and plastic strain of a workpiece. The comparisons on the prediction of cone spinning cracks and splitting spinning cracks using the original and modified Lemaitre criteria show that, the prediction of the modified Lemaitre criterion is in better agreement with experiment results. The influences of deviation and mandrel rotation on the distribution and variation of damage value during cone spinning are obtained by the modified Lemaitre criterion. The results show that, the damage value is the smallest and it is most evenly distributed at zero deviation, and the damage occurrence zone under a large negative deviation is different from that under a large positive deviation. For the former, damage mainly occurs in the top zone where large tension stress exists and where there is a contact deformation zone under the action of the rollers, but for the latter damage mainly occurs in the wrinkled flange impacted by rollers. At a given feed ratio, the less the mandrel rotational speed, the slower the damage develops, and the more helpful it is for cone spinning to continue successfully.

Key words: ductile fracture, Lemaitre criterion, nonlinearity, cone spinning, splitting spinning, damage

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