Dynamic Force and Torque Analysis of Spherical Four Link Mechanisms

1983 ◽  
Vol 105 (3) ◽  
pp. 492-497 ◽  
Author(s):  
A. T. Yang ◽  
Sun Zhishang

In this paper we present a dynamic analysis of a general spherical four-link mechanism whose links have arbitrary mass distribution. Results, which are in explicit analytical expressions in terms of inertia-induced forces and moments in links, are useful for optimum design of the mechanism under high-speed operation.

2017 ◽  
Vol 9 (5) ◽  
Author(s):  
Na Li ◽  
Hai-Jun Su ◽  
Xian-Peng Zhang

Dynamic characteristics analysis is very important for the design and application of compliant mechanisms, especially for dynamic and control performance in high-speed applications. Although pseudo-rigid-body (PRB) models have been extensively studied for kinetostatic analysis, their accuracy for dynamic analysis is relatively less evaluated. In this paper, we first evaluate the accuracy of the PRB model by comparing against the continuum model using dynamic simulations. We then investigate the effect of mass distribution on dynamics of PRB model for compliant parallel-guided mechanisms. We show that when the beam mass is larger than 10% of the motion stage, the error is significant. We then propose a new PRB model with a corrected mass distribution coefficient which significantly reduces the error of the PRB model. And the dynamic responses are also analyzed according to the corrected mass distribution coefficient. At last, a compliant double parallel-guiding mechanism is used as a case study for validation of the new PRB model for dynamics of compliant mechanisms.


Author(s):  
J. R. Dooley

Abstract Spherical four-bar linkages are compact mechanisms capable of motion outside the plane and transmission between intersecting shafts. Dynamic analyses of spherical four-bar linkages are complicated by the fact that they are statically indeterminate. Previous solutions have used an RCCC approximation to model the 4R linkage. This paper extends previous results to include the material elasticity in the dynamic analysis. The results of this more accurate model are compared to those obtained from the RCCC model and it is shown that the RCCC approximation yields significant errors.


2021 ◽  
pp. 1-23
Author(s):  
Zhiwei Wang ◽  
Zhonghui Yin ◽  
Paul Allen ◽  
Ruichen Wang ◽  
Qing Xiong ◽  
...  

2011 ◽  
Vol 133 (2) ◽  
Author(s):  
Venkata K. Yadalam ◽  
B. F. Feeny

A method of modal analysis by a mass-weighted proper orthogonal decomposition for multi-degree-of-freedom and distributed-parameter systems of arbitrary mass distribution is outlined. The method involves reduced-order modeling of the system mass distribution so that the discretized mass matrix dimension matches the number of sensed quantities, and hence the dimension of the response ensemble and correlation matrix. In this case, the linear interpolation of unsensed displacements is used to reduce the size of the mass matrix. The idea is applied to the modal identification of a mass-spring system and an exponential rod.


2014 ◽  
Vol 50 (2) ◽  
pp. 765-768 ◽  
Author(s):  
Haijun Zhang ◽  
Weijie Xu ◽  
Shuhong Wang ◽  
Youpeng Huangfu ◽  
Guolin Wang ◽  
...  

2018 ◽  
Vol 180 ◽  
pp. 01005 ◽  
Author(s):  
Andrzej Wilk

Transmission of electrical energy from a catenary system to traction units must be safe and reliable especially for high speed trains. Modern pantographs have to meet these requirements. Pantographs are subjected to several forces acting on their structural elements. These forces come from pantograph drive, inertia forces, aerodynamic effects, vibration of traction units etc. Modern approach to static and dynamic analysis should take into account: mass distribution of particular parts, physical properties of used materials, kinematic joints character at mechanical nodes, nonlinear parameters of kinematic joints, defining different parametric waveforms of forces and torques, and numerical dynamic simulation coupled with FEM calculations. In this work methods for the formulation of the governing equations of motion are presented. Some of these methods are more suitable for automated computer implementation. The novel computer methods recommended for static and dynamic analysis of pantographs are presented. Possibilities of dynamic analysis using CAD and CAE computer software are described. Original results are also presented. Conclusions related to dynamic properties of pantographs are included. Chapter 2 presents the methods used for formulation of the equation of pantograph motion. Chapter 3 is devoted to modelling of forces in multibody systems. In chapter 4 the selected computer tools for dynamic analysis are described. Chapter 5 shows the possibility of FEM analysis coupled with dynamic simulation. In chapter 6 the summary of this work is presented.


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