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41.
This paper deals with the prototype of a new pivot bearing having two degrees of freedom. The idea of the pivot bearing is based on a continuous velocity joint (CVJ). The experimental axial stiffness and contact pressure are compared with those determined by theoretical analysis. Then, it is confirmed that the pivot bearing swings smoothly with a range of ±25°. Furthermore, the stiffness of the bearing increases as the swinging angle becomes larger. Therefore, this newly developed pivot bearing may be applied to a parallel mechanism, a joint of robot and so on. 相似文献
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44.
3自由度并联柔索驱动变刚度操作臂的刚度控制 总被引:9,自引:2,他引:7
利用柔索的弹性及驱动冗余性构造了一种3自由度并联柔索驱动变刚度操作臂,在静力学与刚度分析的基础上,进行刚度控制研究。首先,将柔索驱动力映射到关节空间,并分析等效关节力与柔索张力和外力的关系, 提出该操作臂的三维力矢量闭合原理。根据微分变换原理进行刚度分析,得到关节刚度矩阵及操作手刚度矩阵, 并进行数值算例分析,结果表明:刚度与柔索的张力有关,调节柔索张力可以改变系统刚度。最后,采用位置与张力混合控制的策略,对该变刚度操作臂进行了刚度控制,并进行了仿真验证。 相似文献
45.
The vertical stiffness and deformation theories of rubber isolators in compression and compression-shear states are systemically researched in the paper, a series of basic concepts, such as origin compression stiffness, origin compression longitudinal elastic modulus, offset vertical stiffness, etc. are suggested with corresponding theoretical formula and experimental estimation method. Based on the basic concepts and newly suggested calculating theories, the deformation calculating theory related to pure compression state and compression-shear state of isolating bearing is established. The vertical stiffness, offset vertical stiffness and deformation tests are performed with nature rubber bearings and lead plug rubber bearings total 16 original specimens to verify the new concepts and computation model of rubber isolators. All test results show that the theories established in the paper are suitable for analyzing the vertical stiffness and deformation of rubber isolators. 相似文献
46.
M. Schüller H. Drobetz H. Redl E.K. Tschegg 《Materials science & engineering. C, Materials for biological applications》2009,29(8):2471-2477
Fractures of the distal radius are with 10% the most frequent fractures of the human skeleton. In order to stabilize the fracture which is essential for succesful bone-healing, distal volar compression using dorsal compression plates is often used. Among the most important, but until now sparsely investigated criteria for implant-quality is the fatigue behaviour of the system of radius and stabilizing implant. Several types of implants were tested in combination with synthetic bones in the fatigue regime. The fatigue behaviour of samples was characterized using the parameters stiffness, tilting angle and reduction of the fracture gap which can be expressed by the permanent deformation of the system. The study of the evolution of these properties allows an interpretation of the mechanisms governing fatigue. Thus, a comparison of different implant types was obtained. Results show that the geometry of the implant as well as the positioning and type of the used screws has a profound effect on the characteristics of the system. 相似文献
47.
Bo Yeon Kim Chang-Boo Kim Seung Gwan Song Hyeon Gyu Beom Chongdu Cho 《Journal of Mechanical Science and Technology》2009,23(5):1396-1405
A finite thin circular beam element for the out-of-plane vibration analysis of curved beams is presented in this paper. Its
stiffness matrix and mass matrix are derived, respectively, from the strain energy and the kinetic energy by using the natural
shape functions derived from an integration of the differential equations in static equilibrium. The matrices are formulated
with respect to the local polar coordinate system or to the global Cartesian coordinate system in consideration of the effects
of shear deformation and rotary inertias. Some numerical examples are analyzed to confirm the validity of the element. It
is shown that this kind of finite element can describe quite efficiently and accurately the out-of-plane motion of thin curved
beams.
This paper was recommended for publication in revised form by Associate Editor Seockhyun Kim
Chang-Boo Kim received his B.S. degree in Mechanical Engineering from Seoul University, Korea in 1973. He then received his D.E.A., Dr.-Ing.
and Dr.-es-Science degrees from Nantes University, France in 1979, 1981 and 1984, respectively. Dr. Kim is currently a Professor
at the School of Mechanical Engineering at Inha University in Incheon, Korea. His research interests are in the area of vibrations,
structural dynamics, and MEMS. 相似文献
48.
N. El Meiche A. Tounsi E.A. Adda-Bedia A. Megueni 《Computational Materials Science》2009,46(4):1102-1108
A modified shear-lag analysis, taking into account the concept of interlaminar shear stress, is employed to evaluate the effect of transverse cracks on the stiffness reductions in different glass/epoxy and graphite/epoxy hybrid cross-ply laminates. The modified shear-lag model is proposed that assumes interlaminar adhesive layer between two neighbouring layers transferring not only interlaminar shear stress but also normal stress. The stress distribution is solved by the used model which rigorously satisfies the stress equilibrium equations, boundary conditions and the traction continuity at interfaces between layers. 相似文献
49.
本文在对柔性多体动力学发展略作回顾的基础上,采用d'Alembert-Lagranse原理,对由基座、(n-1)个柔性连杆及端部负载组成、相互之间由柱铰联结的柔性链式多体系统进行理论建模;柔性杆模态取三维梁单元进行有限元离散;算法上选用Gear算法克服柔体动力学微分方程的刚性(Stiffness)问题。成功地进行了一种工况的失重柔性机械臂的动力学数值计算,为在其上进一步实施控制打下了良好的基础。 相似文献
50.
本文介绍了单层和多层U形膨胀节刚度的主要计算式和刚度测试结果,并将测试结果与有关理论公式计算结果进行了分析比较,评价了公式的准确性。 相似文献