共查询到18条相似文献,搜索用时 171 毫秒
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应用伪刚体方法设计直角柔性铰链双柔性平行四杆结构时,为满足臂杆为刚性杆的假设,要求臂杆厚度远远大于柔性铰链厚度.设计常根据经验,缺乏相关的理论依据.本文通过对直角柔性铰链平行四杆结构进行刚度误差分析,得到臂杆等效为刚性杆的设计可行域.首先利用积分法求得考虑臂杆变形的精确刚度;然后利用有限元分析方法验证此刚度为精确理论计算刚度;最后,分析虚功原理法求得的理想刚度和积分法精确刚度之间的相对误差,研究其随结构参数的变化规律,并得到臂杆等效为刚性杆的值域,即应用伪刚体模型设计直角柔性铰链双柔性平行四杆的设计可行域. 相似文献
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基于集总解析建模方法和构件有限元分析建立包含驱动副、被动万向铰链和运动杆件弹性变形以及预载作用下的Stewart机构刚度矩阵模型。采用添加虚拟铰链等效构件弹性的方式,将分支等效为一系列刚性构件经由主、被动副以及虚拟铰链连接的形式,给出了运动关节和虚拟铰链变量对机构末端位姿的运动学Jacobian矩阵的数值计算方法,应用虚功原理得到静平衡方程,最终建立了机构无预载以及预载下的刚度矩阵模型。该模型不仅考虑了控制环路刚度,还将构件柔性的有限元分析结果与解析建模相结合,在降低计算成本的同时保证了精度。通过一机构分析实例,考察了两种模型下刚度分布的差异。 相似文献
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一类桥式直接耦合柔性机构的刚度与应力分析 总被引:1,自引:1,他引:0
分析了一类桥式直接耦合柔性机构的精确的刚度和应力模型.分别采用伪刚体模型和卡氏第二定理推导了该柔性机构理论刚度模型,利用两个理论模型与有限元模型的结果进行对比,并采用正交实验法全面分析了柔性铰链的寄生刚度和旋转刚度的精度对其刚度性能的影响.研究结果表明:该柔性机构的寄生刚度影响较小,误差贡献率小于3%;旋转刚度的精度影响较大,通过选择精确的旋转刚度公式可以得到精确的理论刚度模型,同有限元结果相比其误差在t/r〈0.65范围内小于8%;与设计实验及其对应的有限元结果的误差分别为4%和3.96%,验证了刚度模型的正确性.基于刚度模型推导了该柔性机构的应力模型,运用正交实验法与有限元结果进行对比,误差小于4%,验证了应力模型的正确性. 相似文献
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新型柔性铰链的柔度计算 总被引:2,自引:0,他引:2
在力或力矩作用下,柔性铰链将会产生相应的微弹性变形,其柔度性能是表征载荷与形变关系的量度,直接影响着柔性铰链的运动精度和综合性能.目前柔性铰链的设计一般基于繁琐的数值积分方法和有限元技术来计算柔性铰链的性能指标.在提出一种新型柔性铰链的基础上,基于弹性静力学基本公式和微积分理论,推导出一种新型柔性铰链的柔度计算公式,为新型柔性铰链的设计提供了理论依据;严格推导出柔性铰链中心轴线上任意位置的变形公式,实现了柔性铰链的精确设计计算.采用ANSYS软件对理论公式的准确性进行验证,两种结果十分吻合. 相似文献
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六自由度微动工作台柔性铰链设计 总被引:4,自引:0,他引:4
主要介绍了用于六自由度微动工作台的柔性铰链即双向柔性铰链和万向柔性铰链的设计过程,根据微动台中柔性铰链的设计要求,分析了微动台运动时驱动力与铰链变形的关系,确定了满足驱动力条件的柔性铰链刚度范围,并结合柔性铰链强度条件、工作台动态特性以及柔性铰链转角刚度与结构尺寸的关系,进一步确定柔性铰链的刚度和结构尺寸,合理设计柔性铰链.另外,通过有限元分析软件分析了柔性铰链最大受力时的应力分布情况.对柔性铰链的强度进行了校核,进一步保证了柔性铰链设计的正确性. 相似文献
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A new type of flexure hinge named the Triple Lamina Emergent Torsional (Triple-LET) was proposed in this paper. Its 3D structure was designed, and its equivalent bending stiffness was also derived. Based on the equivalent formula and the finite element simulation analysis, the equivalent bending stiffness of the Triple-LET and the LET flexure hinge with the same overall dimensions were analyzed and compared. It was concluded that under the same torque, the Triple-LET flexure hinge can realize larger deformation than the LET flexure hinge. Thus, the proposed new flexure hinge is presented as a compliant joint suitable for applications where large angular rotation is desired. Failure analyses of the Triple-LET and the LET flexure hinges were also carried out, respectively. The analysis results show that the Triple-LET flexure hinge made of polypropylene can reach 180° with no plastic deformation, while the LET flexure hinge with the same overall dimensions will plastically deform once the bending angle is greater than 161.4°. The results also indicate that the range of bending angles of the Triple-LET flexure hinge made of beryllium bronze is from 0° to 128.2°, which is two times larger than that of the LET flexure hinge. 相似文献
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为了分析两种柔性铰链导向机构的稳定性以及柔性铰链参数对导向机构稳定性的影响,本文结合卡氏位移定理和能量法,分别推导了柔性铰链导向机构在运动方向、垂直于运动方向和绕z轴转动方向的刚度计算公式,并应用推导公式对两种导向机构3个方向上刚度进行实例对比,分别计算其3个方向上的谐振频率,并根据谐振频率分析稳定性.最后改变柔性铰链的参数,用MATLAB分析其对导向机构稳定性的影响.结果表明,刚度推导公式的有限元验证和理论计算结果误差在1.10%~13.79%,证明了推导公式的正确性;同时,谐振频率的理论计算数据对比表明双平行四杆导向机构具有更好的稳定性,MATLAB分析得出铰链的切口半径r对微动平台的稳定性和承载能力影响程度最大.谐振频率的对比分析和柔性铰链参数对稳定性的影响分析为微动平台设计时导向机构的选取提供了参考. 相似文献
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为提高柔性支承精密定位系统的行程,以传统直圆型柔性铰链为基本单元,提出一种新型大行程串联柔性机构.刚度与最大应力是影响大行程柔性机构性能的两个重要参数.采用伪刚体模型法,结合材料力学相关理论,建立了该柔性机构刚度和最大应力的理论模型.理论计算结果与非线性有限元分析结果相符,证明理论模型的正确性.在此基础之上,分析了大行程串联柔性机构的设计方法,验证了设计实例在大行程内的可靠性.脉冲响应测试实验结果表明由大行程串联柔性机构支承的精密定位系统定位误差不大于60nm. 相似文献
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Dominik Kern Malte Rösner Elisabeth Bauma Wolfgang Seemann Rolf Lammering Thomas Schuster 《Forschung im Ingenieurwesen》2013,77(3-4):117-125
This article is supposed to serve as a guide for the design of flexure hinges that act as rotational joints. Firstly, flexure hinges with concentrated and distributed compliance are reviewed. They can be modeled by linear beam theories or by the theory of Elastica, respectively. Secondly, the transition between these limit cases is investigated by finite element methods (FEM). A planar symmetric flexure hinge with a circular notch serves as an exemplary geometry. By extending the notch the compliance is distributed. The deflection curves and the kinetics of desired and parasitic motions are chosen as key features to be studied. The corresponding results are compressed into a pseudo-rigid-body model (PRBM) approximation for a range of geometries. It turned out that the concentrated compliance matches best with an ideal rotational joint, but even for small displacements large stresses occur so that its range of operation is small. Distributing the compliance increases the range of operation, however stiffness within the task space decreases dramatically so that the design of a flexure hinge becomes a tradeoff between the two concurring goals large stiffness and large range of operation. 相似文献
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直角柔性铰链的力学特性 总被引:3,自引:0,他引:3
为了深入分析精密传动用柔性铰链的机械性能,在研究常用结构形式柔性铰链力学特性的基础上,对变形敏感的直角柔性铰链的力学特性进行了分析.建立了直角柔性铰链空间力学模型,推导了空间刚度矩阵表达式.在此基础上。从柔性铰链基本结构尺寸等方面研究了影响柔性铰链刚度性能的因素,研究发现影响柔性铰链变形性能的刚度系数与柔性铰链几何尺寸参数和构成柔性铰链材料的弹性模量密切相关.研究表明,当柔性铰链的有效长度增加或材料的弹性模量降低时,其各方面的刚度系数均有不同程度的降低.研究工作对深入分析柔性铰链力学特性、优化设计压电驱动器结构,提高其综合性能具有一定的意义. 相似文献
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Md Rashadul Islam Mesbah U. Ahmed Rafiqul A. Tarefder 《International Journal of Pavement Engineering》2016,17(3):265-274
This study measures the cross-anisotropy of gyratory, kneading and field-compacted hot-mix asphalt samples of two sizes. One set of cube samples were subjected to compression through the top face and the other set through the side face. In addition, two sets of beam samples were tested for flexure stiffness using load on both the top and side faces. Results show that the side faces can sustain an average compressive stress of 0.89, 0.91 and 0.77 times of the top faces for kneading, gyratory and field-compacted cube samples, respectively. The average flexure stiffness of the side face is 0.85 times of that of the top face. For comparison, finite element model (FEM) was developed to predict pavement stress–strain under wheel load. In addition, stress–strain data from a field-instrumented pavement section on Interstate 40 in New Mexico were collected. The FEM-simulated vertical stress shows a close match with collected stress at cross-anisotropy value of 0.8. 相似文献
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目的研究冷轧铝带卷取内部应力的分布情况以及影响因素,为铝带卷筒的设计提供参考。方法通过冷轧铝板压缩实验,测定铝带径向压缩系数与应力的关系曲线;采用非线性有限差分法对卷取过程和内部应力进行仿真;分析线性、一次非线性和二次非线性材料模型以及卷筒刚度对带卷内部应力分布的影响。结果径向压缩系数的理论值与实验值有较好的一致性,卷筒刚度对铝带卷内层应力影响较大,而对外层影响很小,卷筒刚度较小时,在卷芯处容易产生塌卷缺陷,卷筒刚度较大时,容易出现扁卷现象。结论计算带卷内部应力分布时,需要考虑铝带卷的各向异性以及层与层之间的紧密程度,合理选择卷筒的刚度对提高卷取质量有很大的实际意义。 相似文献