摘要
采用了一个由简单机构建立的材料热力学一致性弹塑性大变形本构模型,该模型满足热力学基本的不可逆约束条件,并考虑到了储存在残余微应力场中的能量,用相应的算法,编制了一个用户子程序UMAT,并将其嵌入到商用软件ABAQUS中,对圆柱形工件在弹性工具中镦粗和闭合模镦粗时的回弹和二次屈服进行了分析。比较模拟和实验所测得的载荷-位移关系,可以看出在镦粗的第一阶段发生塑性变形,工件在轴向加载过程中产生的横向变形受到了由于模具的弹性变形引起的径向约束,载荷迅速增加;第二阶段轴向压力减少,模具回弹使得工件的径向变形得以恢复,但随着塑性应变的增加,发生工作强化;第三阶段模具约束解除,工作的径向尺寸增加。用该本构模型对闭合模镦粗过程的计算,表明计算结果与实验结果是一致的。
A thermomechanically consistent constitutive model for finite elastoplastic deformation is established based on the simple mechanical model, and the material user subroutine, UMAT, is programmed for embedding in the commercial software, ABAQUS, together with this new consistent 3-D constitutive model for large elastoplastic deformation and the corresponding numerical algorithm, where the fundamental constraints of irreversible thermodynamics are satisfied and the energy stored in the residual microstress fields is taken into account. The spring back and secondary yielding of cylindrical billets in elastic tools during upsetting and closed-die upsetting are analyzed. Comparison of the load-displacement relationship between the computed and experimental measurement indicates that the experimental data are limited to 32% of the original height, three phases of plastic deformation in an upsetting phase when the load increases rapidly fill the onset of upsetting, then work-hardening occurs as plastic strain developed, and the third phase of load increases rapidly with increase of load-carrying area.
出处
《应用力学学报》
EI
CAS
CSCD
北大核心
2005年第2期180-183,i003,共5页
Chinese Journal of Applied Mechanics
基金
国家自然科学基金项目(10272119)
教育部跨世纪优秀人才项目基金资助
关键词
有限变形
弹塑性
本构模型
镦粗
回弹
二次屈服
finite deformation, elastoplasticity, constitutive model, upsetting, springback, secondary yield.