基于柔性铰链通用模型的柔性位移放大机构建模方法研究
发布时间：2019-02-15 11:42
【摘要】：作为柔性铰链机构的核心单元,柔性铰链的选型与参数设计直接关系到机构的整体性能。由于对各种切口型式的柔性铰链的研究是独立完成的,每种铰链都对应一套十分复杂的设计计算公式,这使得柔性铰链机构的设计者在选择铰链型式时难度很大。在进行柔性铰链参数设计之前,设计者主要根据经验来完成柔性铰链的选型,这样难以保证所选择的铰链切口型式最佳。柔性铰链的通用模型方法,通过通用的解析模型将多种切口形状的柔性铰链统一起来,从而将柔性铰链切口型式的选择和参数设计两个过程合二为一。论文基于圆锥曲线类柔性铰链的通用模型,以桥式柔性位移放大机构为研究对象,研究柔性位移放大机构的运动静力学和动力学建模、应力分析以及涉及柔性铰链切口选型和机构几何参数(包括柔性铰链的几何参数)的多目标优化设计。论文完成的主要工作有:(1)利用圆锥曲线的统一极坐标方程,提出了一种圆锥曲线类柔性铰链的通用模型,并基于小变形梁假设,推导了柔性铰链沿各个方向柔度的解析表达式;基于圆锥曲线类柔性铰链的通用模型,综合考虑机构中柔性铰链的切口形状及几何参数、机构中刚性杆的几何参数,建立了柔性位移放大机构的静力学分析模型;基于该模型分析了柔性铰链切口形状及机构几何参数对机构静力学性能的影响,以及柔性铰链几何参数加工误差对机构静力学性能的影响。(2)基于力插值的有限元法,采用单位载荷法推导了柔性铰链的通用位移插值函数,并利用位移插值函数给出了圆锥曲线类柔性铰链的一致质量矩阵表达式。基于圆锥曲线类柔性铰链的通用模型,建立了单个柔性铰链的动力学方程,并分析了柔性铰链切口形状及几何参数对其基频的影响。(3)分别基于伪刚体模型和多柔体系统动力学理论,建立了柔性位移放大机构的动力学分析模型;基于圆锥曲线类柔性铰链的通用模型,分析了机构中柔性铰链的切口形状及机构几何参数对放大机构最低阶固有频率的影响。(4)基于圆锥曲线类柔性铰链的通用模型,研究了平面载荷作用下柔性铰链中的应力分布,并根据畸变能密度屈服准则,给出了柔性铰链最大名义应力的计算公式及强度校核条件;基于有限元仿真分析数据,采用数值拟合法,得到了圆锥曲线类柔性铰链的拉伸应力集中系数和弯曲应力集中系数的经验计算公式,并考虑应力集中影响给出了平面载荷作用下柔性铰链及位移放大机构最大应力的计算公式。(5)根据使用性能原则,在保证机构固有频率的前提下,以柔性铰链的失效抗力指标为材料选择原则,基于Ashby图法分析了柔性铰链的材料选择,给出了几种适合加工柔性铰链机构的材料。(6)在综合考虑静力学、动力学性能及应力条件下,给出了位移放大机构的综合评价函数,并进行了位移放大机构的参数优化设计。根据优化结果加工样机,并搭建样机实验平台,通过实验测试了位移放大机构样机的位移放大比,有限元仿真结果和实验结果验证了理论模型的正确性。
[Abstract]:As the core unit of the flexible hinge mechanism, the selection and parameter design of the flexible hinge are directly related to the overall performance of the mechanism. Since the study of flexible hinges for various cut-outs is done independently, each hinge corresponds to a complex set of design formulas, which makes the designer of the flexible hinge mechanism difficult to select in the choice of the hinge type. Prior to the design of the flexible hinge parameters, the designer is primarily based on experience to select the flexible hinge, which makes it difficult to ensure that the selected hinge cut type is optimal. The universal model of the flexible hinge is used to unify the flexible hinges of various cut-out shapes through a universal analytical model, so that the choice of the flexible hinge cut-out type and the parameter design are combined into one. Based on the general model of the flexible hinge of the cone curve, the paper studies the static and dynamic modeling of the flexible displacement amplifying mechanism by using the bridge type flexible displacement amplification mechanism as the research object. The stress analysis and the multi-objective optimization design involving the selection of the flexible hinge cut and the geometric parameters of the mechanism, including the geometric parameters of the flexible hinge. The main work of the thesis is as follows: (1) Using the uniform polar coordinate equation of the conic curve, a general model of the flexible hinge with a conic curve is proposed, and the analytical expression of the flexibility of the flexible hinge in various directions is derived based on the hypothesis of the small deformation beam. Based on the general model of the flexible hinge of the conical curve, the geometrical parameters of the flexible hinge in the mechanism and the geometric parameters of the rigid rod in the mechanism are taken into consideration, and the static analysis model of the flexible displacement amplifying mechanism is established. Based on this model, the influence of the shape of the flexible hinge notch and the geometric parameters of the mechanism on the static performance of the mechanism is analyzed, and the influence of the processing error of the flexible hinge on the static performance of the mechanism is analyzed. (2) Based on the finite element method of force interpolation, the general displacement interpolation function of the flexible hinge is derived by the unit load method, and the uniform quality matrix expression of the flexible hinge of the conic curve is given by using the displacement interpolation function. The dynamic equation of a single flexible hinge is established based on the general model of the flexible hinge of the conic curve, and the influence of the shape and the geometric parameters of the flexible hinge on the fundamental frequency is also analyzed. (3) the dynamic analysis model of the flexible displacement amplification mechanism is established based on the pseudo-rigid body model and the multi-soft body system dynamics theory, The influence of the notch shape of the flexible hinge and the geometric parameters of the mechanism on the lowest order natural frequency of the amplifying mechanism is analyzed. (4) The stress distribution in the flexible hinge under the action of plane load is studied based on the general model of the flexible hinge of the conic curve, and the calculation formula and the strength check condition of the maximum nominal stress of the flexible hinge are given according to the distortion energy density yield criterion. based on the finite element simulation analysis data, the empirical formula of the tensile stress concentration coefficient and the bending stress concentration coefficient of the conical curve type flexible hinge is obtained by adopting the numerical simulation method, The calculation formula of the maximum stress of the flexible hinge and the displacement amplifying mechanism under the action of a plane load is given in consideration of the influence of the stress concentration. (5) According to the principle of service performance, on the premise of ensuring the natural frequency of the mechanism, the material selection principle of the flexible hinge is analyzed based on the failure resistance index of the flexible hinge, and the material selection of the flexible hinge is analyzed based on the Ashby method, and a plurality of materials suitable for processing the flexible hinge mechanism are provided. (6) Under the conditions of static, dynamic and stress, the comprehensive evaluation function of the displacement amplification mechanism is given, and the parameter optimization design of the displacement amplification mechanism is carried out. According to the optimization result, the prototype is processed, and the experimental platform of the prototype is set up. The displacement amplification ratio, the finite element simulation result and the experimental results of the displacement amplification mechanism prototype are tested by the experiment. The correctness of the theoretical model is verified.
【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】：2014
【分类号】：TH112
本文编号：2423310
[Abstract]:As the core unit of the flexible hinge mechanism, the selection and parameter design of the flexible hinge are directly related to the overall performance of the mechanism. Since the study of flexible hinges for various cut-outs is done independently, each hinge corresponds to a complex set of design formulas, which makes the designer of the flexible hinge mechanism difficult to select in the choice of the hinge type. Prior to the design of the flexible hinge parameters, the designer is primarily based on experience to select the flexible hinge, which makes it difficult to ensure that the selected hinge cut type is optimal. The universal model of the flexible hinge is used to unify the flexible hinges of various cut-out shapes through a universal analytical model, so that the choice of the flexible hinge cut-out type and the parameter design are combined into one. Based on the general model of the flexible hinge of the cone curve, the paper studies the static and dynamic modeling of the flexible displacement amplifying mechanism by using the bridge type flexible displacement amplification mechanism as the research object. The stress analysis and the multi-objective optimization design involving the selection of the flexible hinge cut and the geometric parameters of the mechanism, including the geometric parameters of the flexible hinge. The main work of the thesis is as follows: (1) Using the uniform polar coordinate equation of the conic curve, a general model of the flexible hinge with a conic curve is proposed, and the analytical expression of the flexibility of the flexible hinge in various directions is derived based on the hypothesis of the small deformation beam. Based on the general model of the flexible hinge of the conical curve, the geometrical parameters of the flexible hinge in the mechanism and the geometric parameters of the rigid rod in the mechanism are taken into consideration, and the static analysis model of the flexible displacement amplifying mechanism is established. Based on this model, the influence of the shape of the flexible hinge notch and the geometric parameters of the mechanism on the static performance of the mechanism is analyzed, and the influence of the processing error of the flexible hinge on the static performance of the mechanism is analyzed. (2) Based on the finite element method of force interpolation, the general displacement interpolation function of the flexible hinge is derived by the unit load method, and the uniform quality matrix expression of the flexible hinge of the conic curve is given by using the displacement interpolation function. The dynamic equation of a single flexible hinge is established based on the general model of the flexible hinge of the conic curve, and the influence of the shape and the geometric parameters of the flexible hinge on the fundamental frequency is also analyzed. (3) the dynamic analysis model of the flexible displacement amplification mechanism is established based on the pseudo-rigid body model and the multi-soft body system dynamics theory, The influence of the notch shape of the flexible hinge and the geometric parameters of the mechanism on the lowest order natural frequency of the amplifying mechanism is analyzed. (4) The stress distribution in the flexible hinge under the action of plane load is studied based on the general model of the flexible hinge of the conic curve, and the calculation formula and the strength check condition of the maximum nominal stress of the flexible hinge are given according to the distortion energy density yield criterion. based on the finite element simulation analysis data, the empirical formula of the tensile stress concentration coefficient and the bending stress concentration coefficient of the conical curve type flexible hinge is obtained by adopting the numerical simulation method, The calculation formula of the maximum stress of the flexible hinge and the displacement amplifying mechanism under the action of a plane load is given in consideration of the influence of the stress concentration. (5) According to the principle of service performance, on the premise of ensuring the natural frequency of the mechanism, the material selection principle of the flexible hinge is analyzed based on the failure resistance index of the flexible hinge, and the material selection of the flexible hinge is analyzed based on the Ashby method, and a plurality of materials suitable for processing the flexible hinge mechanism are provided. (6) Under the conditions of static, dynamic and stress, the comprehensive evaluation function of the displacement amplification mechanism is given, and the parameter optimization design of the displacement amplification mechanism is carried out. According to the optimization result, the prototype is processed, and the experimental platform of the prototype is set up. The displacement amplification ratio, the finite element simulation result and the experimental results of the displacement amplification mechanism prototype are tested by the experiment. The correctness of the theoretical model is verified.
【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】：2014
【分类号】：TH112
【参考文献】
相关期刊论文 前1条
1 陈蕴博;岳丽杰;;机械工程材料优选方法的研究现状[J];机械工程学报;2007年01期
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