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Modeling of compliant mechanisms incorporating flexure hinges is mainly focused on linear methods. However, geometrically nonlinear effects cannot be ignored generally. This work shows that nonlinear behavior plays an important role in the deformation and stress analysis, which consequently impacts the design of compliant mechanisms. In this study a nonlinear higher order finite beam element based modeling approach is presented strongly reducing the computation time of nonlinear models. Planar deformation and mechanical stress of a single circular flexure hinge under a wide range of loads is modeled and computed with the proposed approach. A comparison with a 3D-nonlinear finite element model shows very good agreement and validates the beam model. It is shown that the linear and nonlinear deformation behavior of a single flexure hinge deviate marginally so that linear modeling approaches are sufficient. Furthermore a planar displacement amplification mechanism incorporating circular flexure hinges is studied by means of the same method highlighting the distinct deviation of the behavior of the geometrically nonlinear model from its linear prediction. In conclusion the nonlinear behavior at the system level can not longer be neglected. Finally, a study shows that different designs of the displacement amplification mechanism are achieved when linear or nonlinear modeling approaches are applied. 相似文献
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采用新型高精度类V型柔性铰链设计了柔性微位移放大机构,以减小该类机构的寄生运动并提高其动力学性能。对类V型柔性铰链与最常见的高精度直圆型柔性铰链的性能进行了比较;在考虑柔性铰链转动中心偏移量的基础上,基于弹性力学和材料力学理论推导了基于类V型柔性铰链和基于直圆型柔性铰链的两类二级杠杆式微位移放大机构的放大比。采用ANSYS软件,建立了放大机构的有限元模型,验证了位移放大比的理论推导,并对上述两类放大机构的位移放大比、寄生运动和固有频率进行了仿真和比较。有限元分析结果显示:基于类V型柔性铰链的放大机构有着更小的寄生运动和更高的固有频率,且前2阶固有频率分别是基于直圆型柔性铰链放大机构的1.68倍和1.41倍。最后,采用微视觉测量系统测量了两类放大机构的位移放大比和寄生运动。结果表明:基于类V型和直圆型柔性铰链放大机构的放大比和相对寄生运动比分别为4.387、4.529和0.314 7、0.334 2,显示类V型柔性铰链用于微位移放大机构可有效减小寄生运动并提高动力学性能。 相似文献
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提出一种新型的单轴柔性铰链结构型式-单边混合柔陛铰链,由半个直圆柔性铰链和半个导角柔性铰链构成.通过有限元方法,分析了一组不同导角半径的单边混合铰链设计实例,结果表明单边该混合柔性铰链相对于一般混和柔性铰链与单边柔性铰链具有更高的柔度.并得到其柔度应力比,可用于定量地比较各种柔性铰链的性能差异.提出的单边混合柔性铰链为面向结构紧凑、大位移、高精度的工程应用提供了有价值的参考. 相似文献
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Dimensionless design graphs for flexure elements and a comparison between three flexure elements 总被引:1,自引:0,他引:1
Wouter O. Schotborgh Frans G. M. Kokkeler Hans Tragter Fred J. A. M. van Houten 《Precision Engineering》2005,29(1):1348
This paper presents dimensionless design graphs for three types of flexure elements, based on finite element analysis. Using these graphs as a design tool, a designer can determine the optimal geometry, based on the stiffness and rotation demands of a flexure element. An example is given using the beam flexure hinge.Between the analyzed flexure hinges, a comparison is made on basis of equal hinge functionality: rotation. The result describes the maximum stiffness properties from different hinges in identical situations. A beam flexure element is preferred over a circular flexure hinge for stiffness demands in a single direction, while a cross flexure element enables medium stiffness in two perpendicular directions. 相似文献
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单边导角形柔性铰链的计算与性能分析 总被引:10,自引:4,他引:10
提出了一种单边导角形柔性铰链,以力学卡氏第二定理和微积分为理论基础,推导了单边导角形柔性铰链柔度和转动精度的闭环解析公式,利用有限元和实验的方法对柔性铰链的柔度公式进行校验。结果表明:有限元和实验方法与闭环解析式的结果基本一致。对单边导角形柔性铰链的性能进行分析,得出了结构参数对其柔度性能的影响关系,并通过与双边导角形柔性铰链比较,分析了单边导角形柔性铰链的转动能力、转动精度和对轴向载荷的影响,为柔性铰链在结构紧凑、大位移场合的工程应用提供了有价值的参考。 相似文献
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This paper proposes a novel analytical model for flexure-based proportion compliant mechanisms. The displacement and stiffness calculations of such flexure-based compliant mechanisms are formulated based on the principle of virtual work and pseudo rigid body model (PRBM). According to the theory and method, a set of closed-form equations are deduced in this paper, which incorporate the stiffness characteristics of each flexure hinge, together with the other geometric and material properties of the compliant mechanism. The rotation center point for a corner-filleted flexure hinge is investigated based on the finite element analysis (FEA) and PRBM. An empirical equation for the rotational angle is fitted in this paper in order to calculate accurately the position of the end-point of the flexure hinge. The displacement proportion equation for such mechanisms is derived according to the new approach. Combining the new proposed design equation and the existed stiffness equation, a new proportion compliant mechanism with corner-filleted flexure hinges is designed by means of the least squares optimization. The designed models are verified by finite element analysis. 相似文献
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对直梁圆角形柔性铰链的柔度矩阵进行了研究。首先,基于悬臂梁理论推导了直梁圆角形柔性铰链平面内变形的解析计算方法,建立了柔性铰链平面内柔度矩阵的闭环解析模型,并给出了rt(r为铰链圆角半径,t为铰链厚度)时柔度矩阵的简化计算公式。然后,建立了直梁圆角形柔性铰链的有限元模型,得到了柔性铰链结构参数r/t和l/t(l为铰链长度)变化时柔度矩阵解析值和有限元仿真值的相对误差,以及r/t变化时柔度矩阵简化解析值和仿真值的相对误差。结果表明:采用悬臂梁理论建立的柔性铰链柔度矩阵模型,当l/t≥4时,柔度矩阵各项参数的理论解析值与有限元仿真值相对误差在5.5%以内,当0.1≤r/t≤0.5时,两者的相对误差能够控制在9%以内,当0.2≤r/t≤0.3时,两者的相对误差能够控制在6.5%以内;当r/t≤0.3时,简化解析值与仿真值的相对误差控制在9%以内,
当r/t≤0.2时,简化解析值与仿真值的相对误差控制在7%以内,从而验证了柔度矩阵闭环解析模型的正确性。建立的直梁圆角形柔性铰链柔度矩阵闭环解析模型可为柔性铰链以及柔性体机构的设计和优化提供理论依据。 相似文献
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基于闭环柔度解析式的双曲线形柔性铰链研究 总被引:1,自引:0,他引:1
提出了一种新型的单轴柔性铰链结构型式一单边双曲线形柔性铰链。以力学卡氏第二定理和微积分为理论基础,推导了单边双曲线形柔性铰链柔度的闭环解析公式,在此基础上,推导出单边双曲线形柔性铰链的转动精度公式,对单边双曲线形柔性铰链的性能进行分析,得出了结构参数对其柔度性能的影响关系。并通过对双边双曲线形柔性铰链比较,分析了单边双曲线形柔性铰链的转动能力、转动精度和对轴向载荷的影响等性能,利用有限元和实验的方法对单边柔性铰链的柔度公式进行校验,结果表明有限元与闭环解析式的偏差小于8%,实验结果和解析式的偏差在7%以内,为柔性铰链在结构紧凑、大位移场合的工程应用提供了有价值的参考。 相似文献
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This article presents a new multi-notched flexure hinge, which consists of two right circular and two parabolic notches, for positioning stages based on compliant mechanisms. First, the configuration of the presented multi-notched hinge is obtained using topology optimization, and the final shape is proposed based on post-processing. Second, the dimensionless empirical equations for the stiffness, rotational precision and stress levels of the flexure hinges are developed using finite element analysis (FEA). Third, based on the established equations, the influences of the geometric parameters on the performance of the flexure hinge are investigated. Finally, to further understand the characteristics of this type of flexure hinge, comparisons with flexure hinges of various shapes are performed in terms of stiffness, rotational precision and stress levels. 相似文献
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本文主要研究了椭圆弧柔性铰链刚度的优化设计方法。首无,针对椭圆弧柔性铰链刚度计算公式过于复杂的问题,采用幂函数非线性曲线拟合的方法,推导了椭圆弧柔性铰链刚度的近似理论计算公式。然后,基于近似理论计算公式,分析了柔性铰链的精度特性及工作时的最大应力;采用GlobalSearch全域优化指令和Fmincon局域优化指令对椭圆弧柔性铰链工作方向的最大刚度进行了优化设计。最后,采用有限元仿真和实验验证的方法证实近似理论计算公式的适用性和优化结果的可靠性。验证显示:实验结果与近似理论计算结果的相对误差小于5%,表明提出的方法不仅省去了繁杂的有限元模型建立以及计算和修改的过程,大大提高了设计效率;而且通过优化计算可以得到椭圆弧柔性铰链的最大刚度。 相似文献
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Compliance-based matrix method for modeling the quasi-static response of planar serial flexure-hinge mechanisms 总被引:1,自引:0,他引:1
A matrix method is proposed to model the direct and inverse quasi-static response of constrained/over-constrained planar serial mechanisms with flexure hinges under bending, axial, and shear planar (three-dimensional) loading and small-deformations. The method uses a basic three-point compliance matrix corresponding to one rigid link and one adjacent flexure hinge that are subjected to one point load. This matrix connects the displacements at a point on the rigid link with the load that is applied at another point on it, and the deformations of the flexure hinge at its distal point. The quasi-static model of planar serial flexure-based mechanisms with multiple links under single/multiple point loading results from linearly superimposing all relevant hinge-link-load triads defined by their three-point matrices. A displacement-amplification planar device with right circularly corner-fileted flexure hinges is studied using several refinement stages of the matrix method to generate a model whose predictions are confirmed by finite element simulation. 相似文献