基于平面连杆构型的多稳态柔顺机构综合与设计方法

发布时间：2018-03-23 22:38

本文选题：柔顺机构　切入点：多稳态机构　出处：《西安电子科技大学》2015年博士论文

【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。
[Abstract]:Compliant multistable mechanisms have multiple stable equilibrium positions in their range of motion and do not require sustained input of energy to maintain these stable equilibrium positions. This unique performance makes them available on switches, valves, relays, Spatial deployable mechanisms have been applied in many fields. Because the motion of compliant multistable mechanism is accompanied by complex nonlinear deformation process of large deflection, It is very difficult to synthesize and design this kind of mechanism. With the support of National Natural Science Foundation, this paper studies the synthesis and design method of compliant multi-steady mechanism. The main work accomplished is as follows: taking a single compliant bistable mechanism and a multistage linkage slider mechanism as the modules, a general configuration of a linear partially compliant multistable mechanism is presented. By using the bistable, external and anti-external characteristics of the compliant bistable mechanism, a compliant mechanism with arbitrary steady-state number can be obtained. The formulas for calculating the motion range of the slider and the distance between the stable equilibrium positions are derived. In this paper, the driving force and potential energy calculation formula of partially compliant multistable mechanism are given, and the partial compliance multistable mechanism designed by this universal configuration is demonstrated by several examples. A fully compliant multi-steady mechanism is obtained by replacing the slider mechanism with a compliant fixed-guide mechanism with initial inclination angle. The pseudo-rigid body model of the compliance fixed-guide mechanism is established. Under the conditions of design constraints such as stress and buckling, the length of compliance segment and the initial inclination angle of the compliant fixed-guide mechanism are given. Methods for determining stiffness and thickness parameters. Four design examples and prototypes demonstrate the effectiveness of the design method. Two compliant bistable mechanisms and a compliant fixed-guide segment are used as modules. Using the difference of critical jump force or steady-state distance between two compliant bistable mechanisms, The configurations of two fully compliant six-stable mechanisms and one fully compliant eight-stable mechanism are given. The superposition of the force-displacement characteristics of two compliant bistable mechanisms with different critical jumping forces and different steady-state distances is analyzed. And the contour drawing method of the global elastic potential energy in the multi-steady state mechanism is presented to analyze the jump of the mechanism between different steady-state states. Three design examples are given. The feasibility of the three configurations is verified by the nonlinear finite element analysis and the prototype. Based on the pseudo-rigid body model of the compliant five-bar mechanism, the static equilibrium equation and the input torque expression of the compliant five-bar mechanism are established. Three motion coefficients of a single input compliant five-bar mechanism are obtained, and a numerical method for determining the kinematic position of a compliant five-bar mechanism is given. The flexible five-bar mechanism with two flexure hinges is taken as an example. The distribution of zero point in the expression of input torque is analyzed, and the conditions for the existence of three stable equilibrium positions and three unstable equilibrium positions are obtained. Three design examples are given to verify the correctness of the equilibrium position of the single-input compliant five-bar mechanism. An unconstrained optimization algorithm and a particle swarm optimization algorithm are presented. The design method of compliant five-bar three-stable mechanism based on. The effectiveness of the two optimal design methods is verified by an example and a prototype. In a word, several new configurations of multi-steady-state compliant mechanism based on planar linkage mechanism are proposed, and some effective design methods are given. It provides valuable reference for researchers in this field.
【学位授予单位】：西安电子科技大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TH112

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