scholarly journals Experimental investigations of the dynamic responses of a multi-link mechanism with revolute clearance joints

2021 ◽  
Vol 13 (4) ◽  
pp. 168781402110125
Author(s):  
Xiaofeng Li ◽  
Deng Zhao ◽  
Fuqi Xie ◽  
Shijing Wu ◽  
XiaoYong Li
Keyword(s):  
Dynamic Responses ◽  
Joint Clearance ◽  
Experimental Investigations ◽  
Clearance Joints ◽  
Continuous Contact ◽  
Clearance Joint ◽  
Link Mechanism ◽  
Driving Speed ◽  
Noise Vibration ◽  
Set Up

Joint clearance is unavoidable in the revolute joint of multi-link mechanism. Excessive value of joint clearance generally leads to the noise, vibration, and fatigue failure. In this paper, a multi-link articulated mechanism system with three revolute clearance joints is selected as the study object. At first, its ideal motion equations and dynamic responses without joint clearance are outlined. Then an experimental rig is set up, and the acceleration responses of the mechanism in different scenarios are investigated. Comparative analysis indicates that in the presence of joints clearance, clear periodic transient impacts appear in the acceleration outputs while this mechanism moves to specific positions, and the impacts amplitude increases along with the clearance size and driving speed. Also, certain sequence among three motion states of clearance joint, named free flight, penetration and continuous-contact is observed twice in one circle movement of the mechanism. Besides, the clearance joint at the end of the transmission chain has greater effects on the mechanism system than the other joints. Finally, flexible rubber sleeves are set into the clearance joints, and the obtained experimental results indicate that the undesired transient impact by clearance joints on the mechanical system can be suppressed by flexible sleeves.

scholarly journals A Study on Clearance Effects on Dynamic Responses of Robot Manipulator

Mechanika ◽  
2021 ◽  
Vol 27 (2) ◽  
pp. 130-138
Author(s):  
Zhengfeng Bai ◽  
Tianxi LIU
Keyword(s):  
Contact Force ◽  
Robot Manipulator ◽  
Dynamic Responses ◽  
Joint Clearance ◽  
Force Model ◽  
Clearance Joints ◽  
Clearance Joint ◽  
Dynamic Performances ◽  
Simulation Results ◽  
The Impact

Clearances caused by assemblage, manufacturing errors and wear, affect inevitably the dynamic responses of mechanisms such as robot manipulator. In this study, the effects of clearance on a robot manipulator system are investigated numerically. The contact behavior along normal and tangential direction of clearance joint is described by a nonlinear contact force model and a modified Coulomb friction model respectively. Then, the dynamics equations of the robot manipulator system are established considering joint clearance. In order to investigate the effects of clearance on dynamic performances of practical mechanism, a planar robot manipulator system on a spacecraft system with a revolute clearance joint is used as the apply example. Four case studies for various clearance sizes are implemented to investigate and discuss the effects of joint clearance. The simulation results indicate that clearance joints have severe effects on the dynamic performances of mechanism system and the impact in clearance joints represented by contact force models must be considered in dynamics analysis and design of mechanism system. The simulation results in this work can predict the effects of clearance on robot manipulator system preferably and it is the basis of precision analysis, robust control system design of robot manipulator system.

scholarly journals Investigation on Dynamics of Mechanical System with Clearance Joint

2014 ◽  
Vol 8 (1) ◽  
pp. 224-229
Author(s):  
Zheng-Feng Bai ◽  
Bin-jiu Yang ◽  
Yi Sun
Keyword(s):  
Mechanical System ◽  
Frequency Domain Analysis ◽  
Friction Model ◽  
Dynamic Responses ◽  
Force Model ◽  
Clearance Joints ◽  
Continuous Contact ◽  
Clearance Joint ◽  
Joint Contact ◽  
Coulomb Friction Model

In this work, the dynamic responses and vibration characteristics of mechanical system with revolute clearance joints are investigated numerically. Considering clearance in joint, the intra-joint contact model that is generated at clearance joints is established using a nonlinear continuous contact force model and the friction effect is considered by using a modified Coulomb friction model. A well-known slider-crank mechanism with a revolute clearance joint is utilized to perform the investigation. The effects of clearance on dynamics of mechanical system are analyzed by timedomain responses and frequency domain analysis. The investigation results show that the dynamic responses of mechanical system with clearance are obviously vibration and the amplitude increases from the mechanism without clearance. The results also indicate that the behavior of mechanism with clearance is nonlinear.

scholarly journals Dynamics of Multibody Systems With Spherical Clearance Joints

2005 ◽  
Author(s):  
P. Flores ◽  
J. Ambro´sio ◽  
J. C. P. Claro ◽  
H. M. Lankarani
Keyword(s):  
Contact Force ◽  
Multibody Systems ◽  
Contact Forces ◽  
Force Model ◽  
Clearance Joints ◽  
Continuous Contact ◽  
Clearance Joint ◽  
Contact Force Model ◽  
Dynamics Of Multibody Systems ◽  
The Impact

This work deals with a methodology to assess the influence of the spherical clearance joints in spatial multibody systems. The methodology is based on the Cartesian coordinates, being the dynamics of the joint elements modeled as impacting bodies and controlled by contact forces. The impacts and contacts are described by a continuous contact force model that accounts for geometric and mechanical characteristics of the contacting surfaces. The contact force is evaluated as function of the elastic pseudo-penetration between the impacting bodies, coupled with a nonlinear viscous-elastic factor representing the energy dissipation during the impact process. A spatial four bar mechanism is used as an illustrative example and some numerical results are presented, being the efficiency of the developed methodology discussed in the process of their presentation. The results obtained show that the inclusion of clearance joints in the modelization of spatial multibody systems significantly influences the prediction of components’ position and drastically increases the peaks in acceleration and reaction moments at the joints. Moreover, the system’s response clearly tends to be nonperiodic when a clearance joint is included in the simulation.

Dynamic characteristics of planar linear array deployable structure based on scissor-like element with differently located revolute clearance joints

2017 ◽  
Vol 232 (10) ◽  
pp. 1759-1777 ◽  
Author(s):  
Bo Li ◽  
San-Min Wang ◽  
Viliam Makis ◽  
Xiang-Zhen Xue
Keyword(s):  
Mechanical System ◽  
Dynamic Characteristics ◽  
Equations Of Motion ◽  
Nonlinear Behavior ◽  
Friction Model ◽  
Dynamic Responses ◽  
Force Model ◽  
Clearance Joints ◽  
Deployable Structure ◽  
Clearance Joint

This paper comprehensively investigates the parametric effects of differently located revolute clearance joints on the dynamic behavior of planar deployable structure based on scissor-like element. Considering the real physical mechanical joints, the normal and the tangential forces in the revolute clearance joints are respectively modeled using Flores contact-force model and LuGre friction model. The resulting forces and moments are embedded in the equations of motion of the scissor deployable structure for accurately describing the effect of joint clearance and governing the dynamic response of this structure. The effects of the main parameters such as the location of the clearance joint, the clearance size and the number of clearance joints on the dynamic characteristics of a multibody mechanical system have been numerically evaluated, and the results indicate that joints at different locations in a mechanical system have different sensitivities to the clearance size, and the more sensitive joint should be controlled to reduce the nonlinear behavior of this structure. Also, it can be concluded that the motion in one revolute clearance joint will affect the motion in the other clearance joints and the dynamic interaction of clearance joints is the important source of structural behavior change. Therefore, in order to accurately predict the dynamic responses of the mechanical system, the clearance effect of each joint on the multibody system should be investigated and understood.

Nonlinear dynamic characteristics and control of planar linear array deployable structures consisting of scissor-like elements with revolute clearance joint

2020 ◽  
pp. 136943322097172
Author(s):  
Bo Li ◽  
San-Min Wang ◽  
Charis J Gantes ◽  
U-Xuan Tan
Keyword(s):  
Friction Coefficient ◽  
Contact Force ◽  
Initial Conditions ◽  
Equations Of Motion ◽  
Force Model ◽  
Deployable Structures ◽  
Clearance Joints ◽  
Continuous Contact ◽  
Clearance Joint ◽  
Parametric Effects

This paper comprehensively deals with the parametric effects of the joint clearance and friction coefficient on the dynamics of planar deployable structures consisting of scissor-like elements (SLEs). The dynamic model for scissor deployable structure is based on a comprehensive consideration of the symmetry and array characteristics of this mechanism and on a Lagrange method, which represents the motion equations. A modified nonlinear contact-force model is employed to evaluate the intrajoint contact force, and the incorporation of the friction effect between the inter-connecting bodies is included in this study. The total impact forces produced in the real mechanical joint are embedded into the dynamics and the differential equations of motion are solved numerically based on a set of initial conditions. The clearance size, angle velocity, and friction coefficient are analyzed and discussed separately. Using Poincaré map, the regular and irregular responses of the deployable mulitibody systems are observed. Next, a control scheme is evaluated to maintain a more stable behavior and continuous contact between the clearance joints. The controlled results are compared with those without control, concluding that some undesired effects caused by the clearance joints can be prevented or reduced, resulting in continuous contact at the clearance joint.

Dynamic analysis of a planar multibody system with multiple revolute clearance joints

2018 ◽  
Vol 233 (10) ◽  
pp. 3429-3443 ◽  
Author(s):  
Xupeng Wang ◽  
Wenzhou Lin ◽  
Xiaomin Ji ◽  
Zhu Gao ◽  
Xiaobo Bai ◽  
...  
Keyword(s):  
Multibody System ◽  
Dynamic Responses ◽  
Force Model ◽  
Nonlinear Phenomenon ◽  
Linkage Mechanism ◽  
Clearance Joints ◽  
Clearance Joint ◽  
Four Bar Linkage ◽  
The Impact ◽  
The Ideal

This paper focuses on the dynamic responses of a planar mechanism with multiple clearance joints. The effect of the impact between the journal and the bearing in the clearance joint is described using an improved impact force model, and a typical four-bar linkage mechanism with multiple clearance joints is presented as an example. Two conditions are considered in this research, one is the single clearance joint with different position, and the other is multiple clearance joints. From a large number of numerical results, some important conclusions are obtained as follows: (1) with the influence of the clearance joint, the dynamic output of system has obvious vibration in comparison to the ideal value. (2) The position of the clearance joint has a clear effect on the response of system; the larger the distance of the clearance joint from the drive motor, the smaller its influence on the output of the system. (3) With the increase in the clearance joint number, the dynamic stability of the multibody system is decreased gradually, and the dynamic characteristic of the system also appears as obvious nonlinear phenomenon. (4) The coupling phenomenon appears when multiple clearance joints in the multibody system are considered, which should be examined seriously during the process of design and numerical analysis.

Dynamic analysis of mechanical system considering radial and axial clearances in 3D revolute clearance joints

2020 ◽  
pp. 107754632095051
Author(s):  
Zheng Feng Bai ◽  
Xin Jiang ◽  
Ji Yu Li ◽  
Ji Jun Zhao ◽  
Yang Zhao
Keyword(s):  
Mechanical System ◽  
Dynamic Characteristics ◽  
Mathematic Model ◽  
Contact Forces ◽  
Dynamic Responses ◽  
Radial Clearance ◽  
Double Pendulum ◽  
Clearance Joints ◽  
Revolute Clearance Joint ◽  
Clearance Joint

In the dynamic modeling and simulation of mechanical system with revolute clearance joint, it is usually assumed that the revolute joint is planar joint with radial clearance, but the axial clearance is ignored. In this article, the dynamic responses of a mechanical system considering both radial and axial clearances in 3D revolute clearance joint are investigated using a computational methodology. First, the mathematic model of 3D revolute clearance joint is established considering the radial and axial clearances. The definitions of the radial and axial clearances, the potential contact modes, contact conditions, and contact detection for 3D revolute clearance joint are presented. Furthermore, the normal and tangential contact force models are established to describe the contact phenomenon and determine the contact forces in revolute clearance joints. Finally, two demonstrative application examples are presented to illustrate the dynamic characteristics of mechanical systems considering both radial and axial clearances in revolute clearance joints. A slider-crank mechanism with planar motion and a double pendulum with spatial motion are investigated. Different cases are presented to analyze the dynamic characteristics of a mechanical system considering radial and axial clearances in 3D revolute clearance joints.

Dynamics Modeling and Simulation of Deployable Mechanism with Double Clearance

2016 ◽  
Vol 693 ◽  
pp. 306-313 ◽  
Author(s):  
Hong Zhou Huang ◽  
Jun Lan Li ◽  
Yun Qiang Yang ◽  
Shao Ze Yan
Keyword(s):  
Modeling And Simulation ◽  
Significant Influence ◽  
Dynamic Performance ◽  
Joint Clearance ◽  
Dynamics Modeling ◽  
Clearance Joints ◽  
Clearance Joint ◽  
Deployable Mechanism ◽  
Joint Vibration ◽  
Multi Body

Space deployable mechanisms have been widely employed in aeronautic industry, and the dynamic performance of the space deployable mechanisms become increasingly important. In this paper, the model of space deployable mechanism with double clearances is established by the multi-body program ADAMS. The deployable mechanism with ideal joint, single clearance joint and double clearance joints are simulated to investigate the effects of double clearance on the dynamic performance of the deployable mechanism. The results reveal that the coupler of double joint clearance has significant influence on dynamic performance of deployable mechanism. The results of simulation could help to predict the joint vibration in space deployable mechanisms.

Dynamic Analysis of a Spatial Mechanism Including Frictionless Spherical Clearance Joint With Flexible Socket

2017 ◽  
Vol 13 (3) ◽  
Author(s):  
Jianhong Hou ◽  
Guofeng Yao ◽  
Huili Huang
Keyword(s):  
Dynamic Response ◽  
Dynamic Analysis ◽  
Coupling Model ◽  
Dynamic Responses ◽  
Flexible Body ◽  
Flexible Coupling ◽  
Spatial Mechanism ◽  
Clearance Joint ◽  
Driving Speed

In this paper, the dynamic response of a spatial four-bar mechanism with a spherical clearance joint with flexible socket is investigated. Previous research treats the socket as a whole rigid part and neglects the flexibility of the socket. In order to better describe the influence of the spherical clearance joint, a rigid-flexible coupling model of a four-bar mechanism is established, in which the socket of the spherical clearance joint is treated as flexible body. The dynamic responses of this spatial mechanism are discussed for the mechanism with a flexible socket and the case with traditional rigid socket. Furthermore, the effects of clearance size and driving speed are also separately discussed. The results demonstrated that the dynamic response of mechanism is affected by the clearance joint. The socket flexibility can relieve the undesired effects of the clearance on the responses of the mechanism with clearance. The flexible socket acts as a suspension for the mechanism with clearance joint.

Wear Analysis of Spatial Parallel Mechanisms With Multiple Three-Dimensional Spherical Clearance Joints

2019 ◽  
Vol 141 (10) ◽  
Author(s):  
Chen Xiulong ◽  
Jia Yonghao
Keyword(s):  
Parallel Mechanism ◽  
Surface Profile ◽  
Friction Model ◽  
Dynamic Responses ◽  
Force Model ◽  
Parallel Mechanisms ◽  
Clearance Joints ◽  
Wear Analysis ◽  
Clearance Joint ◽  
Analysis Of Dynamics

The goal of this work is to investigate the dynamic responses of the parallel mechanism with irregular clearances caused by wear and to further reveal the influences of multiple clearance interaction on wear. The motion model and the force model of spherical clearance joint based on a continuous contact force model and a static friction model are established. The dynamic equation of the spatial parallel mechanism considering two spherical clearance joints is derived. A general wear analysis strategy to establish spherical clearance joint with sustainable updation of the surface profile is presented, and the dynamic responses of parallel mechanism after wear are studied. The interaction between two wear joints with different initial clearance values is further investigated. The results show that it is necessary to consider the factor of irregular clearances caused by wear in the analysis of dynamics behavior for precision mechanisms. Proper distribution of clearance values can reduce wear of clearance joint and improve the useful life of mechanism to a certain extent. This work provides a foundation for life prediction and reliability analysis of parallel mechanisms.

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