【作者】 勾燕洁；

【导师】 贾建援； 陈贵敏；

【作者基本信息】 西安电子科技大学 ， 机械电子工程， 2015， 博士

【摘要】 柔顺多稳态机构在其运动范围内具有多个稳定平衡位置,而且不需要持续输入能量来维持这些稳定平衡位置,这种独特的性能使其在开关、阀门、继电器、空间可展开机构等领域获得诸多应用。由于柔顺多稳态机构的运动伴随着复杂的大挠度非线性变形过程,使得这类机构的综合与设计难度很大。本文在国家自然科学基金的支持下,开展对柔顺多稳态机构综合与设计方法的研究,完成的主要工作如下所述：以单个柔顺双稳态机构和多级连杆滑块机构为模块,给出了一种直线型部分柔顺多稳态机构的通用构型。通过单独或混合使用两种综合方法,利用柔顺双稳态机构的双稳态特性、外特性和反外特性,可以得到具有任意稳态数的柔顺机构。推导了滑块的运动范围和各稳定平衡位置之间的距离计算公式,给出了部分柔顺多稳态机构的驱动力和势能计算公式,并通过多个实例展示了这种通用构型设计出的部分柔顺多稳态机构。在上述通用构型的基础上,用具有初始倾斜角的柔顺固定－导向机构取代连杆滑块机构,获得了全柔顺的多稳态机构。建立了柔顺固定-导向机构的伪刚体模型,在综合考虑应力和屈曲问题等设计约束条件下,给出了柔顺固定-导向机构的柔顺片段长度、初始倾斜角、刚度和厚度等参数的确定方法。四个设计实例和样机演示了该设计方法的有效性。以两个柔顺双稳态机构和一个柔顺固定-导向片段为模块,利用两个柔顺双稳态机构的临界跳转力或稳态距离的差异,给出了两种全柔顺六稳态机构和一种全柔顺八稳态机构的构型。分析了具有不同临界跳转力和不同稳态距离的两个柔顺双稳态机构力-位移特性的叠加,以及多稳态机构中整体弹性势能的等高线绘制方法,以此分析机构在不同稳态之间的跳转。给出三个设计实例,并用非线性有限元分析及样机验证了三种构型的可行性。基于柔顺五杆机构伪刚体模型建立了柔顺五杆机构的静平衡方程和输入力矩表达式,得到了单输入柔顺五杆机构的三个运动系数,并给出了用运动系数确定柔顺五杆机构运动位置的数值方法。以含有两个柔性铰链的柔顺五杆机构为例,分析了输入力矩表达式的零点分布情况,得到了存在三个稳定平衡位置和三个非稳定平衡位置的条件,进而指导柔顺五杆三稳态机构的设计。三个设计实例验证了单输入柔顺五杆机构平衡位置的正确性。给出了一种基于无约束优化算法和一种基于粒子群优化算法的柔顺五杆三稳态机构设计方法,并用实例和样机验证了两种优化设计方法的有效性。总而言之,本论文提出了几种基于平面连杆机构的多稳态柔顺机构新构型,并给出了行之有效的设计方法,为本领域的研究人员提供了有价值的参考。更多还原

【Abstract】 A compliant multistable mechanism is capable of steadily staying at multiple distinct posi-tions without power input. Many applications including switches, valves, relays, positioners, and reconfigurable robots may benefit from multistability. Because the motion of a compli-ant multistable mechanism is always accompanied by complex nonlinear large deflections of the compliant members, it is difficult to synthesize and design a compliant mechanism with more than two stable equilibrium positions. Supported by the National Natural Science Foundation of China, this dissertation studies on the synthesis and design approaches for the compliant multistable mechanisms. The main works include:Based on a single compliant bistable mechanism and several link-slider modules, this dis-sertation presents two synthesis approaches for compliant multistable mechanisms, which utilize the bistable, the post-bistable and the reverse behaviors of the compliant bistable mechanism. Compound use of both approaches is also discussed. The equations are de-rived for calculating the motion ranges of the sliders, the distances of the stable equilibrium positions, the actuating force and the potential energy of the multistable mechanisms. The synthesis approaches are validated by several design examples and prototypes.By replacing each link-slider module in the configurations of the above compliant multi-stable mechanisms by an end-effector, a general configuration of the fully compliant mul-tistable mechanisms is obtained. The pseudo-rigid-body model method is used to derive the displacement and spring-back force formulas of the end-effectors. According to the al-lowable stress and the critical buckling load, the design parameters of the end-effector are determined. The effectiveness of the design approach is demonstrated by the successful operation of four fully compliant multistable mechanisms with four, seven and eight stable equilibrium positions.Three fully compliant multistable mechanism configurations are presented through employ-ing one end-effector and two compliant bistable mechanisms with different switching forces and different distances between the two stable equilibrium positions. The force-deflection characteristics of the two bistable mechanisms connected in series is obtained and the plot-ting approach for contour of the potential energy is provided, so as to analyze the motion of the compliant multistable mechanisms. Two examples with six stable equilibrium positions and one example with eight stable equilibrium positions are provided; the nonlinear finite element analysis results and a prototype verify the feasibility of the three configurations.The force and moment equilibrium equations and the input moment formulas are derived based on the pseudo-rigid-body model for the compliant five-bar mechanism. Three kine-matic coefficients are obtained by solving the moment equilibrium equations, and the nu-merical method for determining the position of the compliant five-bar mechanism driven by one moment is provided. By taking the compliant five-bar mechanism including two flexure hinges as an example, the solutions for the input moment equations are discussed, the condi-tions of existing three stable and three unstable equilibrium positions are obtained to design the compliant five-bar tristable mechanism, and are validated by three design examples.Finally, two design approaches based on unconstrained optimization algorithm and parti-cle swarm optimization algorithm are described to develop the compliant five-bar tristable mechanism, and two design examples are given to validate the proposed methods.In general, several novel compliant multistable mechanism configurations based on planar linkages are proposed, and the effective design approaches are presented to facilitate the design for the compliant multistable mechanisms.更多还原