基于变胞副阻力梯度的变胞机构设计方法

发布时间：2018-12-16 19:51

【摘要】：变胞机构是机构学研究的一个新的领域,它的提出给机构学带来了新鲜空气。变胞源机构具有多个自由度,变胞机构在运动过程中需要多个变胞副的约束来保证运动的确定性以及时序要求,而变胞副是通过约束两构件之间的阻力来实现作用的,所以有必要对多个变胞副之间阻力关系进行研究,本文的主要研究内容包括：首先,归纳了实现构件在非主动控制条件下实现合并与分离的方式,也就是变胞方式主要包括：力变胞,几何变胞,组合变胞等。利用这几类的变胞方式,分别针对转动类变胞副和移动类变胞副设计出多种变胞运动副,并分析了单个变胞副相对运动过程中阻力的变化趋势。其次,分别分析了两个典型的变胞机构,2自由度5杆机构和3自由度6杆机构。通过变胞源机构与各构态机构的拓扑图分析,运动副运动状况分析,得到构态变换过程中多个变胞副阻力变化状况,证明了变胞副阻力梯度的存在和阻力之间应当满足的原则等,建立了一种阻力梯度的求解方法。每一个相对运动着的变胞副应当满足最小阻力原则,并且在运动过程中其余变胞副的约束状况不得发生改变,从而才能够满足任务时序要求和运动的确定性,为变胞机构的设计工作打下基础。最后,基于前面得到的变胞副阻力梯度原则,对于一个已知的工作任务,建立了一种变胞机构的设计方法,并对设计方法进行了实例验证和动力学仿真验证。首先将工作任务进行动作分解,分解动作能够通过一类基本机构来实现,所有分解动作对应的机构就能够组成一个方案组合,通过一系列的筛选和机构的综合,能够得到变胞源机构。通过运动副运动,构态转换时序,变胞副类型分析等,选择到合适的变胞副,并使其满足阻力梯度原则。针对板坯剪切机构,利用建立的设计方法设计出变胞机构,并进行了动力学仿真,验证了阻力梯度准则的正确性和设计方法的可行性。
[Abstract]:Metamorphic mechanism is a new field of mechanism research, which brings fresh air to mechanism. The metamorphic mechanism has many degrees of freedom. In the process of motion, the metamorphic mechanism needs many constraints to ensure the certainty and timing of the motion, and the variable pair works by constraining the resistance between the two components. Therefore, it is necessary to study the resistance relationship between several metamorphic pairs. The main contents of this paper are as follows: firstly, the ways to realize the merging and separation of components under the condition of non-active control are summarized. That is, metamorphosis mainly includes: force cell, geometric cell, combinatorial metamorphosis and so on. Based on these metamorphic patterns, several metamorphic pairs are designed for rotational metamorphic pairs and mobile metamorphic pairs, and the variation trend of resistance in the relative motion of single metamorphic pair is analyzed. Secondly, two typical metamorphic mechanisms, 2 DOF 5 bar mechanism and 3 DOF 6 bar mechanism are analyzed respectively. By analyzing the topological diagram of the metamorphic mechanism and the mechanism of each structure, and analyzing the motion state of the motion pair, the change of the resistance of the mutual-cell pair in the process of the transformation of the structure state is obtained. It is proved that the existence of resistance gradient of metamorphic pair should be satisfied with the principle of resistance, and a method of solving resistance gradient is established. Each pair with relative motion should satisfy the principle of minimum resistance, and the constraint conditions of the remaining pairs should not be changed in the course of motion, so that the requirements of task timing and the certainty of movement can be satisfied. It lays a foundation for the design of metamorphic mechanism. Finally, based on the principle of resistance gradient of metamorphic pair, a design method of metamorphic mechanism is established for a known task, and the design method is verified by example and dynamic simulation. First of all, the task can be decomposed into action, which can be realized by a kind of basic mechanism. All the mechanisms corresponding to the decomposition actions can form a scheme combination, through a series of screening and mechanism synthesis. The metamorphic source mechanism can be obtained. The suitable metamorphic pair was selected through kinematic pair motion, structural transformation time series, metamorphic pair type analysis and so on, and the resistance gradient principle was satisfied. According to the slab shear mechanism, the variable cell mechanism is designed by using the established design method, and the dynamic simulation is carried out to verify the correctness of the resistance gradient criterion and the feasibility of the design method.
【学位授予单位】：东北大学
【学位级别】：硕士
【学位授予年份】：2011
【分类号】：TH112

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