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J Xiao - One of the best experts on this subject based on the ideXlab platform.
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a comprehensive dynamic model of double row spherical roller bearing model development and case studies on surface defects preloads and Radial Clearance
Mechanical Systems and Signal Processing, 2008Co-Authors: M Cao, J XiaoAbstract:Bearing excitation is one of the most important mechanical sources for vibration and noise generation in machine systems of a broad range of industries. Although extensively investigated, accurately predicting the vibration/acoustic behavior of bearings remains a challenging task because of its complicated nonlinear behaviors. While some ground work has been laid out on single-row deep-grooved ball (DGB) bearing, comprehensive modeling effort on spherical roller bearing (SRB) has yet to be carried out. This is mainly due to the facts that SRB system carries one more extra degree of freedom (DOF) on the moving race (could be either inner or outer race) and in general has more rolling elements compared with DGB. In this study, a comprehensive SRB excitation source model is developed. In addition to the vertical and horizontal displacements considered in previous investigations, the impacts of axial displacement/load are addressed by introducing the DOF in the axial shaft direction. Hence, instead of being treated as pre-assumed constants, the roller-inner/outer race contact angles are formulated as functions of the axial displacement of the moving race to reflect their dependence on the axial movement. The approach presented in this paper accounts for the point contacts between rollers and inner/outer races, as well as line contacts when the loads on individual rollers exceed the limit for point contact. A detailed contact-damping model reflecting the influences of the surface profiles and the speeds of the both contacting elements is developed and applied in the SRB model. Waviness of all the contact surfaces (including inner race, outer race, and rollers) is included and compared in this analysis. Extensive case studies are carried out to reveal the impacts of surface waviness, Radial Clearance, surface defects, and loading conditions on the force and displacement responses of the SRB system. System design guidelines are recommended based on the simulation results. This model is also applicable for bearing health monitoring, as demonstrated by the numerical case studies showing the frequency response of the system with moderate-to-large point defects on both inner and outer races, as well as the rollers. Comparisons between the simulation results and some conclusions reflecting common sense available in open literature serves as first hand partial validation of the developed model. Future validation efforts and further improvement directions are also provided. The comprehensive model developed in this investigation is a useful tool for machine system design, optimization, and performance evaluation.
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a comprehensive dynamic model of double row spherical roller bearing model development and case studies on surface defects preloads and Radial Clearance
Mechanical Systems and Signal Processing, 2008Co-Authors: J XiaoAbstract:Bearing excitation is one of the most important mechanical sources for vibration and noise generation in machine systems of a broad range of industries. Although extensively investigated, accurately predicting the vibration/acoustic behavior of bearings remains a challenging task because of its complicated nonlinear behaviors. While some ground work has been laid out on single-row deep-grooved ball (DGB) bearing, comprehensive modeling effort on spherical roller bearing (SRB) has yet to be carried out. This is mainly due to the facts that SRB system carries one more extra degree of freedom (DOF) on the moving race (could be either inner or outer race) and in general has more rolling elements compared with DGB. In this study, a comprehensive SRB excitation source model is developed. In addition to the vertical and horizontal displacements considered in previous investigations, the impacts of axial displacement/load are addressed by introducing the DOF in the axial shaft direction. Hence, instead of being treated as pre-assumed constants, the roller-inner/outer race contact angles are formulated as functions of the axial displacement of the moving race to reflect their dependence on the axial movement. The approach presented in this paper accounts for the point contacts between rollers and inner/outer races, as well as line contacts when the loads on individual rollers exceed the limit for point contact. A detailed contact-damping model reflecting the influences of the surface profiles and the speeds of the both contacting elements is developed and applied in the SRB model. Waviness of all the contact surfaces (including inner race, outer race, and rollers) is included and compared in this analysis. Extensive case studies are carried out to reveal the impacts of surface waviness, Radial Clearance, surface defects, and loading conditions on the force and displacement responses of the SRB system. System design guidelines are recommended based on the simulation results. This model is also applicable for bearing health monitoring, as demonstrated by the numerical case studies showing the frequency response of the system with moderate-to-large point defects on both inner and outer races, as well as the rollers. Comparisons between the simulation results and some conclusions reflecting common sense available in open literature serves as first hand partial validation of the developed model. Future validation efforts and further improvement directions are also provided. The comprehensive model developed in this investigation is a useful tool for machine system design, optimization, and performance evaluation.
Agnieszka Chudzik - One of the best experts on this subject based on the ideXlab platform.
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effect of ring misalignment on the fatigue life of the Radial cylindrical roller bearing
International Journal of Mechanical Sciences, 2016Co-Authors: Bogdan Warda, Agnieszka ChudzikAbstract:Abstract An effect of ring misalignment in the Radial cylindrical roller bearing on its fatigue life is analysed. In order to predict the fatigue life, a methodology, which allows bearing geometrical parameters, including profiles of rolling generators, bearing Radial Clearance, angular tilting of rings and complex load to be accounted for, was applied. Stress distributions indispensable to calculate the predicted fatigue life were determined via solving the Boussinesq problem numerically for the elastic half-space and with the FEM. In the calculation of the predicted bearing life fatigue, Lundberg and Palmgren's model was employed. The results of calculations were compared to the recommendations of manufacturers of roller bearings referring to admissible tilt angles of rings.
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fatigue life prediction of the Radial roller bearing with the correction of roller generators
International Journal of Mechanical Sciences, 2014Co-Authors: Bogdan Warda, Agnieszka ChudzikAbstract:Abstract The paper presents the methodology of fatigue life prediction of Radial cylindrical roller bearings, which allows to take into account in the fatigue life calculation geometric parameters of the bearing, including Radial Clearance and the profiles of rollers. In addition, the methodology takes into account the effect of combined load and misalignment of the bearing rings on the fatigue life. The stress distributions which are necessary to calculate the predicted fatigue life were determined by solving numerically the Boussinesq problem for elastic half-space. The Lundberg and Palmgren model was used for the calculation of the predicted fatigue life of the bearing. The paper focuses on determining the effect of roller profiles on the bearing fatigue life. Pressure distributions obtained by the described methodology were compared to the distributions determined according to the finite element method. The calculated fatigue life of cylindrical roller bearing was compared with the experimental results.
S P Harsha - One of the best experts on this subject based on the ideXlab platform.
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analysis of nonlinear phenomena in high speed ball bearings due to Radial Clearance and unbalanced rotor effects
Journal of Vibration and Control, 2010Co-Authors: S H Upadhyay, S P Harsha, S C JainAbstract:The dynamic behavior of a high speed unbalanced rotor supported on roller bearings with damping has been studied, focusing particular attention on its nonlinear aspects. The non-linearity in the rotor bearing system has been considered mainly due to Hertzian contact, unbalanced rotor effect and Radial internal Clearance. This is modeled as an oscillating spring-mass-damper system. Various techniques like Time Response curves, Poincare maps, Orbits plots, fast Fourier transformation, Hopf bifurcation and Phase Trajectory are used to study the nature of response. The motion of an unbalanced rotor is categorized with respect to the ratio of the Forcing/Natural frequency of the system as Harmonic, Sub-harmonic, Quasi periodic and Chaotic. The results show the appearance of instability and chaos in the dynamic response as the speed of the rotor-bearing system is changed. Period doubling and mechanism of intermittency have been observed that lead to chaos. The outcomes illustrate the appearance of instability a...
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vibration signature analysis of a rotor bearing system using response surface method
ASME 2009 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference, 2009Co-Authors: P K Kankar, Satish C Sharma, S P HarshaAbstract:The vibration response of a rotor bearing system is extremely important in industries and is challenged by their highly non-linear and complex properties. This paper focuses on performance prediction using response surface method (RSM), which is essential to the design of high performance rotor bearing system. Response surface method is utilized to analysis the effects of design and operating parameters on the vibration response of a rotor-bearing system. A test rig of high speed rotor supported on rolling bearings is used. Vibration response of the healthy ball bearing and ball bearings with various faults are obtained and analyzed. Distributed defects are considered as surface waviness of the bearing components. Effects of internal Radial Clearance and surface waviness of the bearing components and their interaction are analyzed using design of experiment (DOE) and RSM.© 2009 ASME
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nonlinear dynamic response of a balanced rotor supported by rolling element bearings due to Radial internal Clearance effect
Mechanism and Machine Theory, 2006Co-Authors: S P HarshaAbstract:This paper presents a model for investigating structural vibrations in rolling element bearings due to Radial internal Clearance. The mathematical formulation accounted for tangential motions of rolling elements as well as inner and outer races with sources of nonlinearity such as Hertzian contact force and internal Radial Clearance resulting transition from no contact to contact state between rolling elements and races. The contacts between rollers and races are treated as nonlinear springs and the springs act only in compression to simulate contact deformation and resulting force. The nonlinear stiffness is obtained by application of equations for the Hertzian elastic contact deformation theory. The effect of Radial internal Clearance for rotor bearing system in which rolling element bearings show periodic, quasi-periodic and chaotic behavior are analyzed. Time response, rotor trajectories, Poincare maps and power spectra are used to elucidate and to illustrate the diversity of system behavior.
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the effect of speed of balanced rotor on nonlinear vibrations associated with ball bearings
International Journal of Mechanical Sciences, 2003Co-Authors: S P Harsha, K Sandeep, Ravi PrakashAbstract:The paper deals with the structural dynamic response of rotor supported by ball bearings. The mathematical model takes into account the sources of nonlinearity such as Hertzian contact force, surface waviness, varying compliance and internal Radial Clearance resulting transition from no contact to contact state between rolling elements and races. In terms of the feature that the nonlinear bearing forces act on the system, a new reduction method and corresponding integration technique is used to increase the numerical stability and decrease computer time for system analysis. The effects of speed of balanced rotor in which ball bearings show periodic, quasi-periodic and chaotic behavior are analyzed. The results are presented in the form of time displacement responses, frequency spectra and Poincare maps. It is implied from the frequency spectra that peak amplitude of vibrations appear at the varying compliance frequency.
H Fouad - One of the best experts on this subject based on the ideXlab platform.
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in vitro evaluation of stiffness graded artificial hip joint femur head in terms of joint stresses distributions and dimensions finite element study
Journal of Materials Science: Materials in Medicine, 2011Co-Authors: H FouadAbstract:The aim of the present work is to evaluate the artificial hip joint femur head that is made of Stiffness Graded (SG) material in terms of joint stresses distributions and dimensions. In this study, 3D finite element models of femur head that is made of SG material and traditional femur heads made of Stainless Steel (SS), Cobalt Chromium alloy (Co Cr Mo) and Titanium alloy (Ti) have been developed using the ANSYS Code. The effects on the total artificial hip joint system stresses due to using the proposed SG material femur head (with low stiffness at the outer surface and high stiffness at its core) have been investigated. Also, the effects on the polymeric cup contact stresses due to the use of different sizes of femur heads, presence of metal backing shell and presence of Radial Clearance (gap) between cup and femur head have been investigated. The finite element results showed that using SG femur head resulted in a significant reduction in the cup contact stresses even for small femur heads compared with Ti alloy, SS and Co Cr Mo femur heads. The presence of Radial Clearance resulted in significant increase in the cup stresses especially for small femur heads. Finally, the presence of SS metal backing shell resulted in slight increase in the hip joint stresses especially for small femur head joints. This work analyzes successfully the usage of proposed SG material as femur head in order to reduce the predicted stresses at the total hip joint replacement due to the redistribution of strain energy in the hip prostheses. Therefore, the present results suggest that minor changes in design and geometrical parameters of the hip joint have significant consequences on the long term use of the joint and should be taken into consideration during the design of the hip joint.
Setsuo Takatani - One of the best experts on this subject based on the ideXlab platform.
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influence of Radial Clearance and rotor motion to hemolysis in a journal bearing of a centrifugal blood pump
Artificial Organs, 2006Co-Authors: H Kataoka, Yuichi Kimura, Hajime Fujita, Setsuo TakataniAbstract:Hemolysis due to narrow Clearance of noncontact bearings is a critical problem for rotary blood pumps. We developed a centrifugal blood pump with a magnetic and hydrodynamic hybrid bearing, and found that the hemolysis in the narrow Clearance depends not only on the Clearance size, but also on the rotor stability. In this study, we quantified the relation between the hemolysis, Radial Clearance (c), and rotor stability through the measurement of the rotor motion and hemolysis. As a result, it was confirmed that the rotor of the current pump is stabilized within the oscillation of 20 microm in blood, and the hemolysis decreases with increase in the c, which is the opposite in the unstable rotor motion with the previous pump. In order to theoretically discuss this hemolysis tendency, we implemented hemolysis estimation in the c according to hydrodynamics and hemodynamics. This estimation can represent the measured hemolysis tendency, and revealed that the flow rate has large influence on the hemolysis in the c.
