摘要
为研究Exechon并联模块的刚度性能,采用子结构综合方法建立该模块的刚度解析模型。分别采用虚拟关节法和有限元法计入各关节和支链体的柔性,并通过推导动平台和支链装配体间的变形协调方程构建出系统的弹性静力学模型。由系统方程抽取出动平台刚度矩阵,据此预估Exechon并联模块在典型位姿和工作全域内的刚度性能,并将其与有限元仿真结果进行对比。结果表明,所建解析模型具有较高计算精度,可快速预估机构工作全域的刚度特性;Exechon并联模块在工作空间任一截面内的刚度关于x轴对称分布,且沿w方向的刚度受机构位形影响较小。
In order to achieve a thorough understanding of the stiffness characteristics of the Exechon parallel kinematic machine（PKM）, an analytical kinetostatic model is proposed by using the substructure synthesis technique. The whole system is decomposed into a moving platform subsystem, three limb subsystems and a fixed base subsystem, which are connected to each other sequentially through corresponding joints. Each limb body is modeled as a spatial beam with rectangular cross-section constrained by two sets of lumped springs. The equilibrium equation of each individual limb assemblage is derived through finite element formulation and combined with that of the moving platform derived with Newtonian method to establish the governing kinetostatic equations of the system after introducing the deformation compatibility conditions between the moving platform and the limbs. The computation for the stiffness of the Exechon PKM at a typical configuration as well as throughout the workspace is carried out. Deformation of the Exechon PKM under an external load is computed by ANSYS Workbench, based on which calculation errors between the finite element method and the proposed analytical method are obtained to illustrate the high accuracy of the analytical model. The numerical simulations reveal a strong position-dependency of the PKM＇s stiffness, which is symmetric about x axis in a work plane due to structural features. It is worthy mentioning that the proposed methodology of stiffness modeling in this paper can also be applied to other overconstrained PKMs and can evaluate the global rigidity over workplace efficiently with minor revisions.
作者
张俊
赵艳芹
ZHANG Jun ZHAO Yanqin(School of Mechanical Engineering, Anhui University of Technology, Ma＇ anshan 243032 State Key Laboratory for Manufacturing Systems Engineering, Xi＇an Jiaotong University, Xi＇an 710049)
出处
《机械工程学报》
EI
CAS
CSCD
北大核心
2016年第19期34-41,共8页
Journal of Mechanical Engineering
基金
"机械制造系统工程"国家重点实验室(西安交大)开放基金(sklms2015004)
"高性能复杂制造"国家重点实验室(中南大学)开放课题(Kfkt2013-12)
上海市复杂薄板结构数字化制造重点实验室开放课题(2014002)资助项目
关键词
并联机构
Exechon
子结构综合
刚度建模
parallel kinematic machine
Exechon
substructure synthesis
stiffness modeling
