Study of the Dynamic Performance of Mechanical Systems With Multi-Clearance Joints

2010 ◽  
Author(s):  
S. M. Megahed ◽  
A. F. Haroun
Keyword(s):  
Contact Force ◽  
Dynamic Performance ◽  
Mechanical Systems ◽  
Local Deformation ◽  
Elastic Behavior ◽  
Contact Period ◽  
Clearance Joints ◽  
Coulomb’S Friction ◽  
Energy Dissipated ◽  
Maximum Impact Force

Joints’ clearance in mechanical systems such as linkage mechanisms and robots is an inevitable matter due to wear of mating parts. The presence of such clearance is a main source of impact forces resulting local deformation, wear and tear of such joints and consequently degradation of system performance. In this investigation, the effect of revolute joints’ clearance on the dynamic performance of mechanical systems is reported. The contact force between the pin (journal) and the bearing of the joint is modeled using Coulomb’s friction law, and contact force approach. This approach takes into consideration the elastic behavior of the collided bodies and the energy dissipated due to collision during the contact period. A computation algorithm is developed with the aid of SolidWorks/CosmosMotion software package. A crank-slider mechanism with one and two clearance-joints working in horizontal or vertical planes is studied. The simulation results point out that the presence of such clearance in the joints of the system understudy leads to high peaks in the characteristic curves of its dynamic and kinematic performance. The amplitudes of these peaks become higher as the number of clearance-joints included in the mechanism increases. For a multi-clearance joints mechanism, the maximum impact force at its joints takes its highest value at the nearest joint to the input link. This study also shows that, when the mechanism works in horizontal plane, the rate of impacts at each clearance-joint increases and consequently the clearance-joints and actuators will deteriorate faster. This means that working of the real mechanisms in vertical plan is more advantageous and improves their performance.

Analysis of the Dynamic Behavioral Performance of Mechanical Systems With Multi–Clearance Joints

2011 ◽  
Vol 7 (1) ◽  
Author(s):  
S.M. Megahed ◽  
A.F. Haroun
Keyword(s):  
Impact Force ◽  
Dynamic Performance ◽  
Mechanical Systems ◽  
Behavioral Performance ◽  
Clearance Joints ◽  
Revolute Joints ◽  
Clearance Joint ◽  
Computation Algorithm ◽  
Maximum Impact Force ◽  
Crank Mechanism

In this investigation, the effect of revolute joints’ clearance on the dynamic performance of mechanical systems is reported. A computation algorithm is developed with the aid of SolidWorks/CosmosMotion software package. A slider-crank mechanism with one and two clearance-joints is studied and analyzed when working in vertical and in horizontal planes. The simulation results point out that the presence of such clearance in the joints of the system understudy leads to high peaks in the characteristic curves of its kinematic and dynamic performance. For a multiclearance joints mechanism, the maximum impact force at its joints takes its highest value at the nearest joint to the input link. This study also shows that, when the mechanism works in horizontal plane, the rate of impacts at each clearance-joint increases and consequently the clearance-joints and actuators will deteriorate faster.

Computational and Experimental Analysis of Mechanical Systems With Revolute Clearance Joints

2013 ◽  
Author(s):  
Sony Cheriyan ◽  
Paulo Flores ◽  
Hamid M. Lankarani
Keyword(s):  
Contact Force ◽  
Computational Models ◽  
Mechanical Systems ◽  
Contact Forces ◽  
Force Model ◽  
Connecting Rod ◽  
Normal Contact ◽  
Clearance Joints ◽  
Coulomb’S Friction ◽  
Experimental Apparatus

The main objective of this work is to present a computational and experimental study on the contact forces developed in revolute clearance joints. For this purpose, a well-known slider-crank mechanism with a revolute clearance joint between the connecting rod and slider is utilized. The intra-joint contact forces that generated at this clearance joints are computed by considered several different elastic and dissipative approaches, namely those based on the Hertz contact theory and the ESDU tribology-based for cylindrical contacts, along with a hysteresis-type dissipative damping. The normal contact force is augmented with the dry Coulomb’s friction force. An experimental apparatus is use to obtained some experimental data in order to verify and validate the computational models. From the outcomes reported in this paper, it is concluded that the selection of the appropriate contact force model with proper dissipative damping plays a significant role in the dynamic response of mechanical systems involving contact events at low or moderate impact velocities.

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.

Hertz Contact Force Model With Permanent Indentation in Impact Analysis of Solids

1992 ◽  
Author(s):  
Hamid M. Lankarani ◽  
Parviz E. Nikravesh
Keyword(s):  
Contact Force ◽  
Impact Analysis ◽  
Equations Of Motion ◽  
Solid Particles ◽  
Hertzian Contact ◽  
Contact Period ◽  
Force Model ◽  
Unknown Parameters ◽  
Contact Force Model ◽  
Energy And Momentum

Abstract A continuous analysis method for the direct-central impact of two solid particles is presented. Based on the assumption that local plasticity effects are the sole factor accounting for the dissipation of energy in impact, a Hertzian contact force model with permanent indentation is constructed. Utilizing energy and momentum considerations, the unknown parameters in the model are analytically evaluated in terms of a given coefficient of restitution and velocities before impact. The equations of motion of the two solids may then be integrated forward in time knowing the variation of the contact force during the contact period. For Illustration, an impact of two soft metallic particles is studied.

On the Comparison of the Dynamic Performance of Open-Loop and Closed-Loop Mechanisms

2014 ◽  
Author(s):  
Jahangir Rastegar ◽  
Dake Feng
Keyword(s):  
Dynamic Response ◽  
Dynamic Systems ◽  
Closed Loop ◽  
Dynamic Performance ◽  
Mechanical Systems ◽  
Open Loop ◽  
Actuation Devices

In general, mechanical systems with closed-loop mechanisms can achieve significantly higher operating speeds as compared to open-loop mechanisms such as robots performing identical tasks. In this brief paper, the reason for the superior dynamic performance of closed-loop mechanisms as compared to open-loop mechanisms performing identical tasks is shown to be the inherent dynamic response limitations of the actuation devices in open-loop dynamic systems. Several examples are provided.

On the Nature of O-Rings in Contact With Rough Surfaces

1988 ◽  
Vol 110 (4) ◽  
pp. 632-637 ◽  
Author(s):  
W. E. Warren ◽  
J. G. Curro ◽  
D. E. Amos
Keyword(s):  
Theoretical Analysis ◽  
Root Mean Square ◽  
Contact Pressure ◽  
Contact Force ◽  
Rough Surfaces ◽  
Fundamental Importance ◽  
Elastic Behavior ◽  
Surface Irregularity ◽  
Mean Square ◽  
Irregular Surfaces

This work provides a theoretical analysis of the elastic behavior of an O-ring compressed between two rigid plates with irregular surfaces. Relations between deflection, contact force and contact pressure are obtained. The contact pressure, which is of fundamental importance in establishing criteria for effective sealing, is dependent upon both the amplitude and wavelength of the surface irregularity. This analysis suggests that surfaces in contact with O-ring seals should be characterized by the root mean square slope Δq in addition to the usual Ra which depends on amplitude only.

Reliability optimization design of a planar multi-body system with two clearance joints based on reliability sensitivity analysis

2018 ◽  
Vol 233 (4) ◽  
pp. 1369-1382 ◽  
Author(s):  
Yong Gao ◽  
Fang Zhang ◽  
Yuanyuan Li
Keyword(s):  
Sensitivity Analysis ◽  
Contact Force ◽  
Optimization Design ◽  
Great Influence ◽  
Force Model ◽  
Reliability Optimization ◽  
Clearance Joints ◽  
Clearance Joint ◽  
Reliability Sensitivity ◽  
Reliability Sensitivity Analysis

A general method for reliability sensitivity analysis and reliability optimization design of planar slider crank mechanism with two clearance joints was presented. A continuous contact force model considering energy dissipation was employed to estimate the contact force acting on the clearance joint. The Monte Carlo method was used to analyze the reliability sensitivity. In addition, based on the Kriging method, a surrogate model was constructed with consideration of explicit function expression. The precision and reliability of the presented method have been successfully demonstrated by numerical simulation. The results show that the number and position of clearance joint considered have a great influence on the maximum allowable displacement of the slider. The changing of the reliability sensitivity for the mean and variance of several random variables has certain regularity. Compared with the determinacy optimization design, the reliability optimization design presented here shows better dynamical performances.

Dynamic Analysis and Wear Prediction of Planar Five-Bar Mechanism Considering Multiflexible Links and Multiclearance Joints

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
Gengxiang Wang ◽  
Hongzhao Liu
Keyword(s):  
Contact Force ◽  
Dynamic Performance ◽  
Contact Forces ◽  
Force Model ◽  
Displacement Curve ◽  
Wear Depth ◽  
Wear Model ◽  
Clearance Joint ◽  
Contact Force Model ◽  
Cylindrical Joint

Effects of wear and member flexibility on the dynamic performance of a planar five-bar mechanism with joint-clearance are investigated. The equation of motion of the mechanism is derived based on the absolute nodal coordinate formulation (ANCF). In order to enhance the accuracy of the contact force, the slope of the load–displacement curve of the cylindrical joint with clearance is used. The contact deformation couples the joint wear to the contact state. The contact force model of Flores and coworkers is improved, by the introduction of the stiffness coefficient. The wear depth is predicted by using the Archard's wear model. Simulations show that the multiclearance joints can generate stronger contact forces relative to single clearance joint case. This leads to more severe wear in the joint. However, the mechanism with multiple flexible links can absorb more of the energy arising from the clearance joint, and this improves the wear phenomenon.

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