3-PRS并联动力头弹性动力学建模与分析
发布时间：2018-07-24 07:53
【摘要】：本文面向航空航天制造业中铝合金构件加工的需求,以一种空间三坐标并联动力头——3-PRS并联动力头为研究对象,对其静、动态特性进行研究,为该类机床的加工精度和加工效率的提高提供理论依据。本文以3-PRS并联动力头为研究对象,首先对其进行结构设计,然后建立了该机构的动力学模型,基于此进行静、动特性分析研究。全文所取得的成果总结如下:首先,采用闭环矢量法,建立该类并联动力头的运动学模型,并依托所建的运动学模型对其进行运动学逆解分析和工作空间分析,旨在明确该并联动力头的运动链尺度和运动极限范围,从而为该类样机的虚拟样机结构设计提供关键参数依据。其次,运用三维建模软件对3-PRS并联动力头的各个部件进行结构设计,并基于软件装配体功能将各个结构组件装配,最终形成3-PRS并联动力头的虚拟样机装配体。以设计出的3-PRS并联动力头虚拟样机为研究分析对象,应用有限元软件对其关键部件进行静力学仿真分析,旨在获得关节刚度设计参数并进一步捕获样机设计的薄弱环节,为3-PRS并联动力头的关键部件及装配体设计提供优化设计理论。然后,基于变形叠加原理与动态子结构综合思想,通过计入各运动铰链的弹性变形以及支链体的结构柔度,运用变形协调关系建立3-PRS并联动力头的系统弹性动力学模型,为研究该类并联动力头系统的静、动态特性能全域快速预估与性能优化设计提供坚实的理论基础。继而,根据上述所建3-PRS并联动力头的弹性动力学模型,可以简化得到该类并联动力头的弹性静力学模型以及关节反力/反力矩方程,进而为深入研究该类并联动力头的静刚度特性和关节力能提供了分析理论。在对可达工作空间内静特性预估分析的基础上,深入研究了动平台位姿转角、机构尺度参数以及关节刚度参数对该类并联动力头静特性的内在作用机理与联系。最后,研究了3-PRS并联动力头系统固有频率的快速预估与动力学优化设计,并以动平台位姿转角、动静平台半径以及支链截面尺寸为参数变量,分析该类机构的低阶固有频率与机构设计参数之间的内在关联。本文的研究方法结合了有限元法和解析法的优点,同时兼具有限元法的计算精度和解析法的效率,也可以扩展到其他类型的并联机构,相关成果可对少自由度机构的结构优化、提高精度等具有指导意义。
[Abstract]:In order to meet the requirement of aluminum alloy component processing in aerospace manufacturing industry, this paper studies the static and dynamic characteristics of 3-PRS parallel power head, which is a kind of spatial three-dimensional parallel power head. It provides a theoretical basis for the improvement of machining accuracy and efficiency of this kind of machine tools. This paper takes the 3-PRS parallel power head as the research object, designs its structure at first, then establishes the dynamic model of the mechanism. Based on this, the static and dynamic characteristics of the mechanism are analyzed and studied. The results obtained in this paper are summarized as follows: firstly, the kinematics model of this kind of parallel power head is established by using closed loop vector method, and the kinematics inverse solution analysis and workspace analysis are carried out based on the kinematics model. The aim of this paper is to make clear the kinematic chain size and the motion limit range of the parallel power head, so as to provide the key parameter basis for the virtual prototype structure design of this kind of prototype. Secondly, three dimensional modeling software is used to design the structure of each component of 3-PRS parallel power head, and based on the function of software assembly, each structural component is assembled, and finally the virtual prototype assembly of 3-PRS parallel power head is formed. Taking the virtual prototype of 3-PRS parallel power head as the research object, the finite element software is used to simulate and analyze the key parts of the virtual prototype in order to obtain the design parameters of joint stiffness and further capture the weak links of the prototype design. The optimal design theory is provided for the design of the key parts and assembly of the 3-PRS parallel power head. Then, based on the principle of superposition of deformation and the comprehensive idea of dynamic substructure, the elastic dynamic model of 3-PRS parallel power head is established by taking into account the elastic deformation of each moving hinge and the structural flexibility of branch chain. It provides a solid theoretical basis for the study of the static and dynamic characteristics of this kind of parallel power head system. Then, according to the elastodynamic model of the 3-PRS parallel power head, the elastic static model and the joint reaction / torque equation of the parallel power head can be simplified. It provides an analytical theory for studying the static stiffness characteristics and joint force performance of this kind of parallel power head. Based on the analysis of the static characteristics in the reachable workspace, the internal mechanism and relation of the kinematic platform pose angle, the mechanism dimension parameter and the joint stiffness parameter on the static characteristics of the parallel power head are studied. Finally, the fast prediction and dynamic optimization design of the natural frequency of the 3-PRS parallel power head system are studied. The dynamic platform position and pose angle, the dynamic and static platform radius and the sectional size of the branching chain are taken as parameter variables. The relationship between the low order natural frequency of this kind of mechanism and the design parameters of the mechanism is analyzed. The research method in this paper combines the advantages of the finite element method and the analytical method. At the same time, it has the accuracy of the finite element method and the efficiency of the analytical method, and can also be extended to other types of parallel mechanism. The related results can optimize the structure of the mechanism with less degrees of freedom. It is of guiding significance to improve the precision.
【学位授予单位】：安徽工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG502
本文编号：2140719
[Abstract]:In order to meet the requirement of aluminum alloy component processing in aerospace manufacturing industry, this paper studies the static and dynamic characteristics of 3-PRS parallel power head, which is a kind of spatial three-dimensional parallel power head. It provides a theoretical basis for the improvement of machining accuracy and efficiency of this kind of machine tools. This paper takes the 3-PRS parallel power head as the research object, designs its structure at first, then establishes the dynamic model of the mechanism. Based on this, the static and dynamic characteristics of the mechanism are analyzed and studied. The results obtained in this paper are summarized as follows: firstly, the kinematics model of this kind of parallel power head is established by using closed loop vector method, and the kinematics inverse solution analysis and workspace analysis are carried out based on the kinematics model. The aim of this paper is to make clear the kinematic chain size and the motion limit range of the parallel power head, so as to provide the key parameter basis for the virtual prototype structure design of this kind of prototype. Secondly, three dimensional modeling software is used to design the structure of each component of 3-PRS parallel power head, and based on the function of software assembly, each structural component is assembled, and finally the virtual prototype assembly of 3-PRS parallel power head is formed. Taking the virtual prototype of 3-PRS parallel power head as the research object, the finite element software is used to simulate and analyze the key parts of the virtual prototype in order to obtain the design parameters of joint stiffness and further capture the weak links of the prototype design. The optimal design theory is provided for the design of the key parts and assembly of the 3-PRS parallel power head. Then, based on the principle of superposition of deformation and the comprehensive idea of dynamic substructure, the elastic dynamic model of 3-PRS parallel power head is established by taking into account the elastic deformation of each moving hinge and the structural flexibility of branch chain. It provides a solid theoretical basis for the study of the static and dynamic characteristics of this kind of parallel power head system. Then, according to the elastodynamic model of the 3-PRS parallel power head, the elastic static model and the joint reaction / torque equation of the parallel power head can be simplified. It provides an analytical theory for studying the static stiffness characteristics and joint force performance of this kind of parallel power head. Based on the analysis of the static characteristics in the reachable workspace, the internal mechanism and relation of the kinematic platform pose angle, the mechanism dimension parameter and the joint stiffness parameter on the static characteristics of the parallel power head are studied. Finally, the fast prediction and dynamic optimization design of the natural frequency of the 3-PRS parallel power head system are studied. The dynamic platform position and pose angle, the dynamic and static platform radius and the sectional size of the branching chain are taken as parameter variables. The relationship between the low order natural frequency of this kind of mechanism and the design parameters of the mechanism is analyzed. The research method in this paper combines the advantages of the finite element method and the analytical method. At the same time, it has the accuracy of the finite element method and the efficiency of the analytical method, and can also be extended to other types of parallel mechanism. The related results can optimize the structure of the mechanism with less degrees of freedom. It is of guiding significance to improve the precision.
【学位授予单位】：安徽工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG502
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