摘要
采用Kirchner对应变时间历程的基本假设,针对振动拉伸建立一个一维粘弹塑性模型;利用MATLAB中的符号计算,推导粘弹塑性本构方程的显式表达式。通过确立粘弹塑性边界并对本构方程进行数值求解,可以确定金属在振动加工过程中,其应力应变在粘弹性与粘塑性之间的变化情况。通过计算瞬时应变的大小与屈服限建立粘弹性变形和粘塑性变形的判断准则。在考虑粘弹塑性本构关系中的后继屈服情况、应变历程、应变率历程及弹性应变等因素后,可以确定单轴振动拉伸时材料变形的动态应力和平均应力。根据所给定的振型参数和材料力学性能参数,结合特定的振动拉伸实例,分别得出金属在准静态拉伸和振动拉伸时的动态应力—时间、动态应力—应变和平均应力—应变率的变化趋势等,实现基于粘弹塑性本构关系的低频振动塑性成形的体积效应机理分析。
The metal deformation is consisted of elastic deformation, plastic deformation, visco-flttidity caused by the elastic and plastic deformation, and the strain ratio effect, creep and stress slack will appear when the metal is deformed. Already existing models which included visco-elastic model, vesco-plastic model and elastic visco-plastic model can＇ t completely with availably describe the metals＇ relationship of stress and strain at the metal deformation process. So a 1 D visco-dasfidty plasticity models which deal with vibration drawbench is built on the basis of the Kirchner＇ s strain course hypothesis; and the illustrative expression of visco-elasticity plasticity constitutive equation is deduced by the MATLAB symbolic operation. By visco-elasticity plasticity boundary defined, the numerical method is used to solve the constructive equation, then the strain and stress variability between the visco-elasticity and viscoplasticity can be described during the vibration plastic process. Under the instantaneeus strain and yield limit calculated, judgement nile about visco-elastic and visco-plastic is estabhshed. Subsequence yield state, strain course, strain ratio course and elastic strain in the constitutive equations is considerated, the dynamic stress and mean stress when are happenned in the vibration drawbench can be obtained. On the basis of special vibration parameters and material mechanical performance parameters, both approximate static drawbench and vibra-drawbench variabilities of dynamic stress-time, dynamic stress-strain and mean stress-strain are got and discussed, then the volume effect mechanism of visco-elasticity plasticity constitutive equations for plastic deformation with low-frequency vibration is quantitatively analyzed.
出处
《机械强度》
EI
CAS
CSCD
北大核心
2007年第2期346-350,共5页
Journal of Mechanical Strength
基金
国家自然科学基金(50665003)
江西省自然科学基金(0150029)资助项目~~
关键词
塑性成形
低频振动
粘弹塑性
本构关系
体积效应
Plastic deformation
Low-frequency vibration
Visco-elasticity plasticity
Constitutive equations
Volume effect
