板材通过拉深筋时的循环塑性变形机理分析  

Research on Cyclic Plastic Deformation Mechanism of Sheet Flowing through Drawbead

作　　者：金淼[1] 李群[1] 蔡星周[1] 董荣梅[1] 

机构地区：[1]先进锻压成形技术与科学教育部重点实验室(燕山大学),秦皇岛066004

出　　处：《机械工程学报》2013年第12期38-42,共5页Journal of Mechanical Engineering

基　　金：国家自然科学基金(50305031);河北省自然科学基金(E2013203271);河北省科技计划(12217621)资助项目

摘　　要：板材通过拉深筋的变形具有明显的循环加载特征,因反向加载时存在包申格效应,所以目前对不同反向加载阶段板材的变形特征还不明确。为研究板材在拉深筋中的循环变形机理,明确不同加载阶段的变形特征及包申格效应的具体体现,考虑板材方向性、加工硬化特性和包申格效应,建立基于Hill正交各向异性屈服条件和Ziegler随动硬化法则的材料模型。分别采用Mises屈服条件的各向同性硬化、Hill屈服条件的随动硬化两种材料模型,对板材通过半圆形拉深筋的循环塑性变形过程进行数值模拟对比分析,并通过试验验证所建材料模型的有效性。分析随动硬化模型下计算所得板材经过拉深筋时的循环变形特征及各加载阶段应力应变的对应关系;揭示包申格效应对应力-应变循环关系的影响规律。对应力应变历程关系曲线的分析显示,不同于现有的分析结果板材在半圆筋中经历了两次弯曲、卸载与反向弯曲的塑性变形过程;板材同一截面上不同积分点在同一加载分支的包申格效应参数不同,同一积分点在不同加载分支的包申格效应参数也不同;随循环加载次数增加,反映不同加载分支硬化情况的切线模量呈显著下降趋势。The deformation of sheet flowing through drawbead is of obvious cyclic loading deformation feature. As the influence of Bauschinger effect in the reverse loading the deformation in different reverse loading stage is not clear now. To investigate the cyclic deformation mechanism of sheet flowing through drawbead, make clear the deformations of different loading stage and the behavior of Bauschinger effect a material model based on Hill yield criterion and Ziegler kinematic hardening rule is built with consideration of the directivity of sheet, work hardening and Bausehinger effect. The numerical simulation comparative analysis of the cyclic plastic deformation process of sheet flowing through semi-cycle drawbead is carded out with two material models, isotropic hardening of Mises yield condition and kinematic hardening of Hill yield condition respectively, and the effectiveness of the material models being built are verified by experiment. The cyclic deformation features of sheet flowing through drawbead and the stress-strain relations at each loading stage are analyzed, and the influence law of Bauschinger effect on the stress-strain relation is revealed. The analysis of the curve of stress-strain relationship shows that sheet through semi-cycle drawbead undergoes twice bending, unloading and reverse bending in the plastic deformation process which is different from the existing results. And the Bauschinger effect factors of different integration points on the same cross section under the same loading branch are different, and so as the factors of the same integration points under different loading branch, What＇s more the tangent modulus corresponding to hardening situations of different loading branch decrease significantly with the increase of cyclic loading numbers.

关 键 词：随动硬化模型 循环加载 包申格效应 拉深筋 切线模量 

分 类 号：TG386[金属学及工艺—金属压力加工]