被动过约束并联机构的受力与数值仿真分析

发布时间：2018-05-08 16:52

本文选题：弹性变形 + 被动过约束并联机构　；参考：《燕山大学》2014年硕士论文

【摘要】：相较于串联机构，并联机构尽管结构相对复杂、工作空间较小、动作相对不灵活，但是刚度大、运动误差无累积、承载重量比大、模块化程度高、响应速度快、成本低、技术附加值高，特别适用于重载高精度的场合或微动场合。过约束并联机构作为特殊的并联机构，具有并联机构的所有优点，在许多场合发挥了重要作用。但是由于过约束并联机构受力分析问题属于静不定问题，研究起来很复杂，目前国内外对过约束并联机构的受力分析问题进行较为系统的研究文献还非常少。因此，本文是在考虑弹性变形时，针对被动过约束并联机构进行的受力与数值仿真分析，主要研究内容包含下面几个方面：应用螺旋理论分析过约束并联机构的运动螺旋系、约束力螺旋系，并定义过约束力螺旋系、等效约束力螺旋系、分析等效约束力螺旋系与六维外力之间的关系；考虑弹性变形时分析了不同分支的刚度矩阵；基于并联机构的变形协调方程，得到机构的整体刚度矩阵及分支末端的约束反力及分支驱动力；根据分支末端的约束反力依次可得到分支各关节的约束力。最终得到求解过约束并联机构受力的理论计算方法，为过约束并联机构的受力分析提供重要的理论指导。应用提出的过约束并联机构的受力理论计算方法，针对三种典型的被动过约束并联机构(3-PRRR三维正交移动过约束少自由度并联机构、二自由度球面定点并联机构、2UPS+SR二维转动过约束并联机构)进行受力分析计算。提出了一种建立过约束并联机构的受力数值仿真方法。该方法首先应用Proe对几种典型的被动过约束并联机构进行三维模型的建立，，并保存为Adams和Ansys能够导入的格式；在Ansys有限元软件中对需要柔性化的杆件进行模态分析，导出模态中性文件；在Adams软件中对三维刚体模型中需要进行柔性化的刚性杆件进行替换或导入，完成刚柔混合模型的建立并进行仿真。通过对并联机构分支进行分类，并在分析被动过约束并联机构的分支特点及分支在约束力螺旋和驱动力螺旋作用下产生的弹性变形特点，得到了分析被动过约束并联机构受力时影响分支受力分析机理非常重要的两点结论。
[Abstract]:Compared with the series mechanism, the parallel mechanism is relatively complex in structure, small in workspace and relatively inflexible in motion, but it has large stiffness, no accumulation of motion error, large load-bearing weight ratio, high modularization, fast response speed and low cost. High added-value technology, especially for heavy-duty and high-precision occasions or fretting occasions. As a special parallel mechanism, overconstrained parallel mechanism has all the advantages of parallel mechanism and plays an important role in many situations. However, due to the static uncertainty of overconstrained parallel mechanisms, the research is very complex. At present, there are few literatures on the mechanical analysis of overconstrained parallel mechanisms at home and abroad. Therefore, this paper is to consider the elastic deformation, the passive over-constrained parallel mechanism force and numerical simulation analysis, the main content of the study includes the following aspects: The screw theory is applied to analyze the kinematic and binding helical system of the parallel mechanism, and the relationship between the equivalent binding helical system and the six-dimensional external force is analyzed by defining the superbinding helical system and equivalent binding helical system. Considering the elastic deformation, the stiffness matrix of different branches is analyzed, and based on the deformation coordination equation of the parallel mechanism, the global stiffness matrix of the mechanism, the constrained reaction force at the end of the branch and the driving force of the branch are obtained. According to the constraint reaction at the end of the branch, the binding force of each joint can be obtained in turn. Finally, the theoretical calculation method for the force of over-constrained parallel mechanism is obtained, which provides an important theoretical guidance for the analysis of the force of over-constrained parallel mechanism. In this paper, three typical passive over-constrained parallel mechanisms are studied by using the theory of force calculation of over-constrained parallel mechanisms, which are 3-PRRR three dimensional orthogonal moving and less degree of freedom parallel mechanisms. The two-DOF spherical fixed-point parallel mechanism is analyzed and calculated by 2 D UPS SR 2 D rotational over-constrained parallel mechanism. In this paper, a numerical simulation method for the force of an overconstrained parallel mechanism is proposed. In this method, three dimensional models of several typical passive over-constrained parallel mechanisms are built by using Proe, which is saved as a format that can be imported by Adams and Ansys, and the modal analysis of the members that need flexibility is carried out in Ansys finite element software. The modal neutral file is derived, and the flexible rigid bar is replaced or imported in Adams software to complete the establishment and simulation of the rigid-flexible hybrid model. By classifying the branches of the parallel mechanism and analyzing the characteristics of the branch of the passive over-constrained parallel mechanism and the elastic deformation characteristics of the branch under the action of the binding screw and the driving force screw, the paper analyzes the characteristics of the branch of the passive over-constrained parallel mechanism. Two important conclusions are obtained that influence the mechanism of branch force analysis when the passive overconstrained parallel mechanism is subjected to force.
【学位授予单位】：燕山大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TH112

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