Analysis of the Dynamic Performance of Multibody Mechanical Systems With Multiple Lubricated Revolute Joints

2012 ◽  
Author(s):  
A. F. Haroun ◽  
S. M. Megahed
Keyword(s):  
Multibody Systems ◽  
Reynolds Equation ◽  
Journal Bearing ◽  
Dynamic Performance ◽  
Fluid Pressure ◽  
Mechanical Systems ◽  
Hertz Contact ◽  
Revolute Joints ◽  
Crank Mechanism ◽  
The Ideal

In this work a method is proposed for modeling and simulation of multibody mechanical systems with multiple lubricated revolute joints with the aid of CAD and dynamic simulators softwares. The hydrodynamic forces produced between joint components due to lubrication are obtained by integrating Reynolds’ equation that is used for evaluating the fluid pressure distribution in the journal–bearing joint. The resulted force equations are combined with Hertz contact model to make a complete model for lubricated revolute joints. This model is used with the aid of SolidWorks/CosmosMotion software package to simulate multibody systems with multiple lubricated revolute joints and a computational algorism is developed in the frame of multibody dynamics methodology. A slider–crank mechanism with two lubricated revolute joints is used as an application example to demonstrate the efficiency and versatility of the proposed method. The simulation results point out that the introduction of a lubricant at the joint clearance makes the performance of the mechanism so close to that of the ideal mechanism that does not suffer from the clearance problem, as well as improves the overall system 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.

Wear Analysis of Two Revolute Joints With Clearance in Multibody Systems

2016 ◽  
Vol 11 (1) ◽  
Author(s):  
Pei Li ◽  
Wei Chen ◽  
Desheng Li ◽  
Rufei Yu ◽  
Wenjing Zhang
Keyword(s):  
Dynamic Analysis ◽  
Multibody Systems ◽  
Mechanical Systems ◽  
Clearance Joints ◽  
Revolute Joints ◽  
Wear Analysis ◽  
Coupling Dynamics ◽  
System Life ◽  
Crank Mechanism

The wear of multiple joints with clearance is one of the main impacts on the life of mechanical systems while very limited study has been done on this subject. To be different with many existed researches focused on the dynamic analysis of multibody systems with multiple clearance joints, the wear of two revolute joints with clearance in multibody systems is analyzed in this paper by coupling dynamics with tribology. Based on a planar slider crank mechanism with two clearance joints, it is observed that the clearance sizes nonlinearly influence the wear depths of the two joints with clearance. Meanwhile, an appropriate relationship between the two joints' clearance sizes can significantly decrease the wear of the joints, which would greatly improve the system life. Both the independent and interactive influences of the two joints with clearances on the wear are investigated in this paper. The relation equations of the two clearances obtained in this work will significantly decrease the wear of the two clearance joints.

Analysis of Static and Dynamic Performance Parameters of Two-Lobe Journal Bearing Operating With Non-Newtonian Lubricant

2019 ◽  
Author(s):  
Ashutosh Kumar ◽  
Sashindra Kumar Kakoty
Keyword(s):  
Couple Stress ◽  
Reynolds Equation ◽  
Journal Bearing ◽  
Variable Viscosity ◽  
Dynamic Performance ◽  
Load Carrying Capacity ◽  
Performance Parameters ◽  
Noticeable Increase ◽  
Load Carrying ◽  
Nano Lubricant

Abstract Static and dynamic performance parameters of two-lobe journal bearing, working with non-Newtonian lubricant has been obtained. Krieger-Dougherty model is used to obtain the effective viscosity of nano-lubricant for a given concentration of solid-particle in base lubricant. Modified Reynolds equation is solved to obtain bearing performance parameters for couple stress model and variable viscosity model. Dynamic coefficients are also determined for various couple stress parameter. Results reveal a noticeable increase in flow co-efficient and load carrying capacity while there is a decrease in friction variable. It also reveals a significant betterment in dynamic co-efficient of bearing.

Elasto-Aerodynamic Lubrication Analysis of a Self-Acting Foil Air Journal Bearing

2011 ◽  
Author(s):  
Hamza Bensouilah ◽  
Mustapha Lahmar ◽  
Benyebka Bou-Sai¨d
Keyword(s):  
Reynolds Equation ◽  
Journal Bearing ◽  
Dynamic Properties ◽  
Dynamic Performance ◽  
Excitation Frequency ◽  
Element Formulation ◽  
Principle Of Superposition ◽  
Technical Literature ◽  
Finite Differences Method ◽  
Stiffness And Damping

Most of elasto-aerodynamic approaches under dynamic conditions proposed in the technical literature include only the static pressure induced deformation of foils. This paper presents a theoretical investigation on the effects of both static and dynamic deformations of the foils on the dynamic performance characteristics and stability of a self-acting air foil journal bearing operating under small harmonic vibrations. To take into account the dynamic deformations of foils, the perturbation method is used for determining the gas-film stiffness and damping coefficients for given values of excitation frequency, compressibility number, and compliance factor of the bump foil. The nonlinear stationary Reynolds’ equation is solved by means of the Galerkin’s finite element formulation while the finite differences method are used to solve the first order complex dynamic equations resulting from the perturbation of the transient compressible Reynolds’ equation. It was found that the dynamic properties and stability of the compliant finite length journal bearing are significantly affected by the compliance of foils especially when the dynamic deformation of foils is considered in addition to the static one by applying the principle of superposition.

Influence of the Lubrication Model on the Dynamic Response of Mechanical Systems

2013 ◽  
Author(s):  
Paulo Flores
Keyword(s):  
Dynamic Response ◽  
Reynolds Equation ◽  
Hydrodynamic Force ◽  
Equations Of Motion ◽  
Mechanical Systems ◽  
Hydrodynamic Forces ◽  
Journal Bearings ◽  
Dynamic Responses ◽  
Force Model ◽  
Revolute Joints

The main objective of this work is to present a study on the use of different hydrodynamic force models on the dynamic response of mechanical systems with lubricated revolute joints. For this purpose, the fundamental issues related to the classical theory of lubrication for dynamically loaded journal-bearings are revised, which is used to evaluate the Reynolds’ equation for dynamic regime. The hydrodynamic forces that develop at the lubricated revolute joints are determined and included into the dynamic equations of motion. In this study, three different approaches are considered to evaluate the hydrodynamic forces, namely the Pinkus and Sternlicht approach for long journal-bearings and the Frêne et al. models for both long and short journal-bearings. Results for a mechanical system with a lubricated revolute joint are presented and used to discuss the main assumptions and procedures adopted in this work. From the computational simulations performed, it can be observed that the hydrodynamic force model play a crucial role in predicting the dynamic behavior of mechanical systems and originate some uncertainties in their dynamic responses.

Influence of dimple location and depth on the performance characteristics of the hydrodynamic journal bearing system

2020 ◽  
Vol 234 (9) ◽  
pp. 1500-1513
Author(s):  
Niranjan Singh ◽  
RK Awasthi
Keyword(s):  
Reynolds Equation ◽  
Journal Bearing ◽  
Dynamic Performance ◽  
Performance Characteristics ◽  
Eccentricity Ratio ◽  
Bearing Surface ◽  
Surface Textures ◽  
Hydrodynamic Journal Bearing ◽  
Theoretical Results ◽  
Bearing System

This paper concerns with theoretical investigation to predict the influence of cylindrical textures on the static and dynamic performance characteristics of hydrodynamic journal bearing system and the performance is compared with smooth surface bearing. The Reynolds equation governing the fluid–film between the journal and the bearing surface is solved numerically with the assistance of finite element method and the performance characteristics are evaluated as a function of eccentricity ratio, dimple depth and its location. In this study, four journal bearing configurations viz: smooth (non-textured), full-textured, partially textured-I, and partially textured-II are considered for the evaluation of theoretical results. The simulated results indicate that the influence of surface textures is more significant when the textures were created in upstream zone of 126°–286° and dimple aspect ratio nearly 1.0.

Modeling Lubricated Revolute Clearance Joints in Multibody Mechanical Systems

2003 ◽  
Author(s):  
P. Flores ◽  
H. M. Lankarani ◽  
J. Ambro´sio ◽  
J. C. P. Claro
Keyword(s):  
High Speed ◽  
Journal Bearing ◽  
Equations Of Motion ◽  
Mechanical Systems ◽  
Hydrodynamic Forces ◽  
Dynamic Loads ◽  
Governing Equations ◽  
Clearance Joints ◽  
Revolute Joints ◽  
System A

This work is concerned with the modeling of lubricated revolute clearance joints in multibody mechanical systems. The existence of the clearance at revolute joints is inevitable in all mechanical systems, and most of them are designed to operate with a lubricant fluid. It is known that the use of lubricant at revolute joints is demonstrated to be an effective way to ensuring better performance of the mechanical systems. The long journal-bearing theory for dynamic loads is used to evaluate the resulting hydrodynamic forces of the pressure distribution in the lubricated revolute joints. These hydrodynamic forces are included into the governing equations of motion of the system. A numerical example is presented in order to demonstrate the efficiency and accuracy of the methodology and procedures adopted. The results are close to those obtained with ideal joints even when simulated in a high-speed mechanism.

A novel transition model for lubricated revolute joints in planar multibody systems

2015 ◽  
Vol 36 (3) ◽  
pp. 279-294 ◽  
Author(s):  
Pei Li ◽  
Wei Chen ◽  
Desheng Li ◽  
Rufei Yu
Keyword(s):  
Multibody Systems ◽  
Transition Model ◽  
Revolute Joints

A General Solution of Reynolds’ Equation for a Full Finite Journal Bearing

1967 ◽  
Vol 89 (2) ◽  
pp. 203-210 ◽  
Author(s):  
R. R. Donaldson
Keyword(s):  
Fourier Series ◽  
Series Solution ◽  
Reynolds Equation ◽  
Journal Bearing ◽  
Load Capacity ◽  
Separation Of Variables ◽  
Hill Equation ◽  
Eigenvalues And Eigenvectors ◽  
General Series ◽  
Bearing Load

Reynolds’ equation for a full finite journal bearing lubricated by an incompressible fluid is solved by separation of variables to yield a general series solution. A resulting Hill equation is solved by Fourier series methods, and accurate eigenvalues and eigenvectors are calculated with a digital computer. The finite Sommerfeld problem is solved as an example, and precise values for the bearing load capacity are presented. Comparisons are made with the methods and numerical results of other authors.

Sign in / Sign up

Export Citation Format

Share Document