scholarly journals Dynamic Response of Multibody Systems With Multiple Clearance Joints

2011 ◽  
Author(s):  
Paulo Flores ◽  
Hamid M. Lankarani
Keyword(s):  
Contact Force ◽  
Multibody Systems ◽  
Equations Of Motion ◽  
Physical And Mechanical Properties ◽  
Contact Forces ◽  
Force Model ◽  
Modeling And Analysis ◽  
Clearance Joints ◽  
Continuous Contact ◽  
Dissipative Term

A general methodology for the dynamic modeling and analysis of planar multibody systems with multiple clearance joints is presented. The inter-connecting body components that constitute a real joint are modeled as colliding bodies, which dynamic behaviors are influenced by geometric, physical and mechanical properties of the contacting surfaces. A continuous contact force model, based on the elastic Hertz theory, together with a dissipative term, is used to evaluate the intra-joint contact forces. The incorporation of the friction, based on the classical Coulomb’s friction law, is also included. The suitable contact force models are embedded into the dynamic equations of motion for the multibody system. A simple mechanical system with multiple clearance joints is used to demonstrate the accuracy and efficiency of the presented approach and to discuss the main assumptions and procedures adopted. The effects of single versus multiple clearance joints are discussed.

scholarly journals Dynamic Response of Multibody Systems with Multiple Clearance Joints

2012 ◽  
Vol 7 (3) ◽  
Author(s):  
Paulo Flores ◽  
Hamid M. Lankarani
Keyword(s):  
Contact Force ◽  
Multibody Systems ◽  
Equations Of Motion ◽  
Physical And Mechanical Properties ◽  
Contact Forces ◽  
Force Model ◽  
Normal Contact ◽  
Clearance Joints ◽  
Continuous Contact ◽  
Dissipative Term

A general methodology for the dynamic modeling and analysis of planar multibody systems with multiple clearance joints is presented. The inter-connecting bodies that constitute a real physical mechanical joint are modeled as colliding components, whose dynamic behavior is influenced by the geometric, physical and mechanical properties of the contacting surfaces. A continuous contact force model, based on the elastic Hertz theory, together with a dissipative term associated with the internal damping, is utilized to evaluate the intra-joint normal contact forces. The incorporation of the friction phenomenon, based on the classical Coulomb’s friction law, is also included in this study. The suitable contact force models are embedded into the dynamic equations of motion for the multibody systems. In the sequel of this process, the fundamental methods to deal with contact-impact events in mechanical systems are presented. Finally, two planar mechanisms with multiple revolute clearance joints are used to demonstrate the accuracy and efficiency of the presented approach and to discuss the main assumptions and procedures adopted. The effects of single versus multiple clearance revolute joints are discussed.

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.

scholarly journals Dynamics of Multibody Systems With Spherical Clearance Joints

2006 ◽  
Vol 1 (3) ◽  
pp. 240-247 ◽  
Author(s):  
P. Flores ◽  
J. Ambrósio ◽  
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, with 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, with 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.

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.

scholarly journals A Study on the Dynamics of Spatial Mechanisms With Frictional Spherical Clearance Joints

2017 ◽  
Vol 12 (5) ◽  
Author(s):  
Filipe Marques ◽  
Fernando Isaac ◽  
Nuno Dourado ◽  
António Pedro Souto ◽  
Paulo Flores ◽  
...  
Keyword(s):  
Friction Force ◽  
Contact Process ◽  
Contact Forces ◽  
Force Model ◽  
Spherical Joint ◽  
Normal Contact ◽  
Clearance Joints ◽  
Dissipative Term ◽  
Contact Points ◽  
Spatial Mechanisms

An investigation on the dynamic modeling and analysis of spatial mechanisms with spherical clearance joints including friction is presented. For this purpose, the ball and the socket, which compose a spherical joint, are modeled as two individual colliding components. The normal contact-impact forces that develop at the spherical clearance joint are determined by using a continuous force model. A continuous analysis approach is used here with a Hertzian-based contact force model, which includes a dissipative term representing the energy dissipation during the contact process. The pseudopenetration that occurs between the potential contact points of the ball and the socket surface, as well as the indentation rate play a crucial role in the evaluation of the normal contact forces. In addition, several different friction force models based on the Coulomb's law are revisited in this work. The friction models utilized here can accommodate the various friction regimens and phenomena that take place at the contact interface between the ball and the socket. Both the normal and tangential contact forces are evaluated and included into the systems' dynamics equation of motion, developed under the framework of multibody systems formulations. A spatial four-bar mechanism, which includes a spherical joint with clearance, is used as an application example to examine and quantify the effects of various friction force models, clearance sizes, and the friction coefficients.

An Overview on Continuous Contact Force Models for Multibody Dynamics

2012 ◽  
Author(s):  
Paulo Flores ◽  
Hamid M. Lankarani
Keyword(s):  
Contact Force ◽  
Multibody Systems ◽  
Contact Forces ◽  
Hertz Contact ◽  
Dynamic Simulations ◽  
Ball Impact ◽  
Continuous Contact ◽  
Multibody Dynamic ◽  
Contact Impact ◽  
Impact Events

The nature of the constitutive contact force law utilized to describe contact-impact events plays a crucial role in predicting the dynamic response of multibody systems. The main goal of this work is present a survey of the literature on the most relevant penalty-force based approaches for multibody dynamic simulations. In this process, the fundamental characteristics of the purely elastic and the dissipative contact force models are analyzed, namely the models which have been developed based on the Hertz contact law. In particular, the different models are compared in this study for a simple impact problem for the sole purpose of comparison of the models and examining their validity compared to those from experiments. Results obtained for a classical ball impact on a massive surface are presented and used to discuss the main assumptions and procedures associated with the different penalty-force approaches. The force models are found to be quite well representative of the contact forces in an impact, and that they can be applied for the analysis of impact in more complex systems a such as the ones in planar and spatial multibody mechanical systems.

A Study on the Dynamics of Spatial Mechanisms With Frictional Spherical Clearance Joints

2016 ◽  
Author(s):  
Filipe Marques ◽  
Fernando Isaac ◽  
Nuno Dourado ◽  
António Pedro Souto ◽  
Paulo Flores ◽  
...  
Keyword(s):  
Friction Force ◽  
Contact Process ◽  
Contact Forces ◽  
Force Model ◽  
Spherical Joint ◽  
Normal Contact ◽  
Clearance Joints ◽  
Dissipative Term ◽  
Contact Points ◽  
Spatial Mechanisms

An investigation on the dynamic modeling and analysis of spatial mechanisms with spherical clearance joints including friction is presented. For this purpose, the ball and the socket which compose a spherical joint are modeled as two individual colliding components. The normal contact-impact forces that develop at the spherical clearance joint are determined by using a continuous force model. A continuous analysis approach is used here with a Hertzian based contact force model, which includes a dissipative term representing the energy dissipation during the contact process. The pseudo-penetration that occurs between the potential contact points of the ball and the socket surface, as well as the indentation rate play a crucial role in the evaluation of the normal contact forces. In addition, several different friction force models based on the Coulomb’s law are revisited in this work. The friction models utilized here can accommodate the various friction regimens and phenomena that take place at the contact interface between the ball and the socket. Both the normal and tangential contact forces are evaluated and included into the systems’ dynamics equation of motion, developed under the framework of multibody systems formulations. A spatial four bar mechanism, which includes a spherical joint with clearance, is used as an application example to examine and quantify the effects of various friction force models, clearance sizes, and the friction coefficients.

Dynamics Analysis of Spatial Multibody System With Spherical Joint Wear

2015 ◽  
Vol 137 (2) ◽  
Author(s):  
Gengxiang Wang ◽  
Hongzhao Liu ◽  
Peisheng Deng
Keyword(s):  
Contact Pressure ◽  
Contact Force ◽  
Contact Area ◽  
Multibody Systems ◽  
Multibody System ◽  
Equations Of Motion ◽  
Force Model ◽  
Spherical Joint ◽  
Wear Model ◽  
Contact Force Model

The influence of the spherical joint with clearance caused by wear on the dynamics performance of spatial multibody system is predicted based on the Archard's wear model and equations of motion of multibody systems. First, the function of contact deformation and load acting on the spherical joint with clearance is derived based on the improved Winkler elastic foundation model and Hertz quadratic pressure distribution assumption. On this basis, considering the influence of clearance size and wear state on the contact stiffness between spherical joint elements, an improved contact force model is proposed by Lankarani–Nikravesh contact force model and improved stiffness coefficient that is the slope of the function of contact deformation and load. Second, due to the complexity for that wear impacts on the surface topography of contact bodies, an approximate calculation method of contact area with respect to the clearance spherical joint is provided for simplifying the computational process of contact pressure in the Archard's wear model. Subsequently, the contact pressure between contact bodies is calculated by the improved contact force model and approximate contact area (ICFM–ACA), which is verified via finite element method (FEM). Moreover, the dynamics model of spatial four bar mechanism considering spherical joint with clearance caused by wear is formulated using equations of motion of multibody systems. Finally, the wear depth of spherical joint with clearance is predicted via two different kinds of contact pressure based on the Archard's wear model (one is from the ICFM–ACA and the other is from FEM), respectively. The numerical simulation results show that the improved contact force model and proposed approximate contact area are correctness and validity for predicting wear in the spherical joint with clearance. Simultaneously, the effect of the spherical joint with clearance caused by wear on the dynamics performance of spatial four bar mechanism is analyzed.

Dynamic characteristics of planar linear array deployable structure based on scissor-like element with joint clearance using a new mixed contact force model

2016 ◽  
Vol 230 (18) ◽  
pp. 3161-3174 ◽  
Author(s):  
Bo Li ◽  
San-Min Wang ◽  
Ru Yuan ◽  
Xiang-Zhen Xue ◽  
Chang-Jian Zhi
Keyword(s):  
Contact Force ◽  
Dynamic Characteristics ◽  
Dynamic Performance ◽  
Equations Of Motion ◽  
Contact Model ◽  
Joint Clearance ◽  
Force Model ◽  
Continuous Contact ◽  
Deployable Structure ◽  
Contact Force Model

This paper aims at investigating precisely the dynamic performance of deployable structure constituted by scissor unit mechanisms with clearance joint. Based on the motion law in real joints, the contact model is established using an improved Gonthier nonlinear continuous contact force model, and the friction effect is considered using LuGre model. Moreover, the resulting contact force is suitable to be included into the generalized force of the equations of motion of a multibody system and contributes to replace motion constraints. In the sequel of this process, the effect of joint clearance is successfully introduced into the dynamical model of scissor deployable structure and the dynamic characteristics of deployable structure with joint clearance are obtained using a direct default correction method, which can directly modify the coordinates and speed of the system to avoid the numerical results divergence. Also, the new hybrid contact force model of revolute joint clearance is verified through comparing with the original model. The numerical simulation results show that the improved contact model proposed here has the great merit that predicts the dynamic behavior of scissor deployable structure with joint clearance.

The effects of joint clearance on the dynamics of the 3RRR planar parallel manipulator

Robotica ◽  
2016 ◽  
Vol 35 (6) ◽  
pp. 1223-1242 ◽  
Author(s):  
S. M. Varedi-Koulaei ◽  
H. M. Daniali ◽  
M. Farajtabar
Keyword(s):  
Parallel Manipulator ◽  
Dynamic Performance ◽  
Contact Forces ◽  
Force Model ◽  
Continuous Contact ◽  
Dissipative Term ◽  
Revolute Joints ◽  
Planar Parallel Manipulator ◽  
Performance Reduction ◽  
Design And Manufacturing

SUMMARYIn reality, clearances in the joints are inevitable due to tolerances, and defects arising from design and manufacturing. Therefore, poor dynamic performance, reduction in components component lifetimes and generation of undesirable vibrations result in impacts of mating parts in the clearance joint. In this study, the dynamic behavior of a planar mechanism with revolute joints, in the presence of clearances is investigated. A continuous contact force model, based on elastic Hertz theory together with a dissipative term, is used to evaluate the contact forces here. Moreover, using a contact model, the effects of working speed and clearance size on the dynamic characteristics of a planar mechanical system are analyzed and compared. Furthermore, numerical results for a 3RRR planar parallel manipulator with six revolute clearance joints are presented.

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