Non-linear dynamic response analysis of cylindrical roller bearings due to rotational speed

2018 ◽  
Vol 233 (2) ◽  
pp. 379-390 ◽  
Author(s):  
Pravajyoti Patra ◽  
V Huzur Saran ◽  
SP Harsha
Keyword(s):  
Dynamic Behaviour ◽  
Hertzian Contact ◽  
Phase Portraits ◽  
Response Analysis ◽  
Roller Bearings ◽  
Contact Points ◽  
Unbalanced Rotor ◽  
Non Linear ◽  
The Impact ◽  
Cylindrical Roller

The dynamic behaviour of cylindrical roller bearings is presented, in both balanced and unbalanced conditions as a function of speed. The stiffness and damping non-linearities at the contact points (due to Hertzian contact force between rollers and races), radial internal clearance and unbalanced rotor force make the bearing system non-linear. Presently, the differential equations representing the dynamics of the cylindrical roller bearings have been obtained using Lagrange’s equation and solved numerically using modified Newmark-β method. The results of the analyses of various motion behaviours are presented as time–displacement responses, orbit plots, phase portraits, Poincaré maps and Fast Fourier Transform plots. The obtained responses revealed the sensitive behaviour of the system from periodic to quasi-periodic and chaotic with speed variations for both balanced and unbalanced rotor conditions. Also, intermittent chaotic behaviour has been observed. A pattern of the interaction between rotational and variable compliance vibration is observed with speed variations. The frequency pattern analysis (with different techniques used like phase/orbit plots and Poincaré plots) for healthy cylindrical bearing and different rotor conditions under different applied non-linearity consideration is a new attempt to analyse dynamic behaviour of the bearing. This analysis is helpful for online monitoring of fault-free cylindrical roller bearings and for studying the impact of speed on system’s dynamical behaviour.

Evaluation of Impact Loads on Offshore Jacket Platform During Float-Over Mating Operation

2019 ◽  
Author(s):  
Gurumurthy Kagita ◽  
Mahesh B. Addala ◽  
Gudimella G. S. Achary ◽  
Subramanyam V. R. Sripada
Keyword(s):  
Time Domain ◽  
Linear Time ◽  
Random Wave ◽  
Impact Loads ◽  
Transient Effects ◽  
Seed Selection ◽  
Mooring Lines ◽  
Contact Points ◽  
Non Linear ◽  
The Impact

Abstract In the mating phase of float-over operation, the topsides deck load from the vessel is transferred onto the jacket either by ballasting the vessel or by the combination of ballasting and hydraulic jacking system. During this phase of operation, the topsides and jacket experience impact loads through the contact points in a short duration of time. To evaluate the impact loads and to capture the transient effects precisely, a non-linear time domain hydrodynamic analysis is required. To obtain the design loads, generally the numerical jacking simulation is initiated at the time instant of maximum wave height when the jacking system is used. However, the conservative response may also depend on the relative velocity between the jacket and topsides legs. In this paper, a series of non-linear time domain as well as linear frequency domain hydrodynamic analyses are performed to evaluate the impact loads between 9000 tonne integrated topsides deck and a 4-legged jacket in a water depth of 50 m during float-over mating operation. The simulations are performed using MOSES software. The float-over hardware such as LMUs (leg mating unit), DSUs (deck support unit), Jacks, Fenders and Mooring lines are modelled as appropriate linear / nonlinear springs. The principle of the mating operation is considered through a combination of vessel ballasting and jacking operation. This paper discusses about random wave seed selection, effect of vessel response and wave headings on the impact loads of LMUs and Jacks/DSUs.

Vibration response analysis of high-speed cylindrical roller bearings using response surface method

2020 ◽  
Vol 234 (2) ◽  
pp. 379-392
Author(s):  
Pravajyoti Patra ◽  
V Huzur Saran ◽  
SP Harsha
Keyword(s):  
Response Surface ◽  
Response Surface Method ◽  
High Speed ◽  
Dynamical Behavior ◽  
Roller Bearing ◽  
Interactive Effects ◽  
Response Analysis ◽  
Roller Bearings ◽  
Surface Method ◽  
Cylindrical Roller

The operating clearance in a bearing influences friction, load zone size and fatigue life of a bearing. Hence, an effort is made to investigate the effect of radial internal clearance on the dynamical behavior of a cylindrical roller bearing system with an unbalance present in the system. The differential equations representing the dynamics of the cylindrical roller bearings have been derived using Lagrange’s equations and solved numerically using the fourth-order Runge-Kutta iterative method. The nonlinear vibration signature has been analyzed due to the clearance and the same is represented by various tools like Acceleration-time plots, Poincaré plots and FFT plots. The approximation method is used to calculate the load distribution and deformation of the individual rollers located at a different position in the load zone, for a preloading/interference fit and positive internal clearance. A response surface method is used to analyze the severity involved in the system due to the combined effect of independent variables like rotor speed, radial load, and radial internal clearance. The observations presented here are not only useful to diagnose the bearing health condition with respect to parametric effects but also exhibit their interactive effects on bearing performance.

scholarly journals Optimization Procedure of Roller Elements Geometry with Regard to Durability of Spherical Roller Bearings

2020 ◽  
Vol 22 (2) ◽  
pp. 68-72
Author(s):  
Jan Steininger ◽  
Stefan Medvecky ◽  
Robert Kohar ◽  
Tomas Capak
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Roller Bearing ◽  
Optimization Procedure ◽  
Parametric Models ◽  
The Finite Element Method ◽  
Roller Bearings ◽  
Contact Points ◽  
The Impact ◽  
Element Method

The article deals with an optimization procedure of roller elements geometry with regard to durability of spherical roller bearings. The aim of the article is to examine the impact of change of the roller elements inner geometry on durability and reliability of spherical roller bearings; the contact strain along a spherical roller by means of the Finite Element Method at contact points of components of a spherical roller bearing by means of designed 3D parametric models. The most appropriate shape of roller elements inner geometry of a bearing from the standpoint of calculated durability was determined based on results of the contact analyses.

Modal and harmonic response analysis of a rolling bearing coupled by rigid and flexible materials

2019 ◽  
Vol 9 (9) ◽  
pp. 1017-1024
Author(s):  
Jianghong Yu ◽  
Lei Xiang ◽  
Wen Yang ◽  
Chao Li ◽  
Yaoyao Deng ◽  
...  
Keyword(s):  
Structural Parameters ◽  
Excitation Frequency ◽  
Roller Bearing ◽  
Response Analysis ◽  
Harmonic Response ◽  
Flexible Materials ◽  
Roller Bearings ◽  
Elastic Composite ◽  
Cylindrical Roller Bearing ◽  
Cylindrical Roller

Elastic composite cylindrical roller bearing is a new type of rolling bearings. Its rolling body is composed of rigid and flexible materials. In order to investigate the modal characteristics and harmonic response rules of the elastic composite cylindrical roller bearings with different structural parameters, we computed the modal solutions of a cylindrical roller bearing and the elastic composite cylindrical roller bearings with filling degrees of 40%, 50% and 65%, and determined the scope of the excitation frequency according to the computed first twelve orders of the modal frequency. On this basis, we analyzed the steady-state response under a sinusoidal alternating load as well as the vibration conditions of the elastic composite cylindrical roller bearings with different filling degrees within the excitation scope, and explored the relationship between the responses such as displacement and stress and the excitation frequency. The results showed that the natural frequencies of the elastic composite cylindrical roller bearings with filling degrees of 40% and 50% were similar to that of a solid bearing, while that of the elastic composite cylindrical roller bearings with a filling degree of 65% was relatively smaller than that of a solid bearing. The vibration modes of the bearings mainly manifested as bending and torsional deformation of the inner rings. Under the action of an excitation load, the peak responses of the bearings occurred near the fifth and sixth orders of the natural frequency. This research can provide a theoretical reference for the optimal design and engineering applications of the elastic composite cylindrical roller bearings.

The Hollow-Ended Roller—A Solution for Improving Fatigue Life in Asymmetrically Loaded Cylindrical Roller Bearings

1972 ◽  
Vol 94 (2) ◽  
pp. 153-162 ◽  
Author(s):  
W. J. Derner ◽  
R. A. Goodelle ◽  
L. E. Root ◽  
R. Rung
Keyword(s):  
Three Dimensional ◽  
Fatigue Tests ◽  
Hertzian Contact ◽  
Heavy Load ◽  
Roller Bearings ◽  
Equal Importance ◽  
Dimensional Finite Element ◽  
Hertzian Contact Stress ◽  
Three Dimensional Finite Element ◽  
Cylindrical Roller

To reduce the influence of misalignment (asymmetrical loading) on cylindrical roller bearings it is necessary to supplement the crown modifications of bearing elements. A unique hollow-ended roller design was developed for this purpose employing a three-dimensional finite element elasticity study to determine the stress state in the flexible rim section. The results when combined with the classical Hertzian contact stress distribution result in an accurate description of the shear stress field throughout the roller rim sections. Results of fatigue tests run under asymmetrically distributed loads supported the analytical efforts demonstrating significant improvements in L10 lives for the hollow-ended roller as compared to a solid roller. Peak stresses occurred in the vicinity of the contact area for both types of rollers with the solid exhibiting stresses 5 percent or more higher than those found in the hollow-ended type. Of equal importance, the observed failure mode for hollow-ended rollers under heavy load fatigue test conditions is one of conventional subsurface initiated O.D. spalling, thereby proving the rim design to be structurally sound.

Dynamic Response of an Unbalanced Rotor Supported on Bearing With Outer Race Waviness

2013 ◽  
Author(s):  
P. K. Kankar ◽  
Satish C. Sharma ◽  
S. P. Harsha
Keyword(s):  
Dynamic Response ◽  
Chaotic Behavior ◽  
Mathematical Formulation ◽  
Rotational Frequency ◽  
Hertzian Contact ◽  
Radial Clearance ◽  
Outer Race ◽  
Unbalanced Rotor ◽  
Non Linear ◽  
Rolling Elements

The paper investigates the non-linear dynamic response of an unbalanced rotor supported on ball bearings with outer race waviness. The excitation is due to unbalanced force and waviness on outer race. The sources of non-linearities are both the radial clearance as well as the Hertzian contact between races and rolling elements. The nonlinear responses due to unbalanced rotor supported on bearings are investigated. The combined effects like non-linear stiffness and non-linear damping for unbalanced rotor with bearing waviness have been considered and analyzed in detail for a rotor bearing system. In the mathematical formulation, the contacts between the rolling elements and the races are considered as an oscillating spring-mass-damper system. The appearance of regions of periodic, sub-harmonic and chaotic behavior is seen to be strongly dependent on the number of waves in the outer race. The results show the appearance of instability and chaos in the dynamic response as the number of waves in the outer race is changed. The study indicates that the interaction of ball passage frequency (ωbp) due to outer race waviness and rotational frequency (X) due to the unbalanced rotor force. Poincaré maps and frequency responses are used to elucidate and to illustrate the diversity of the system behavior.

Sign in / Sign up

Export Citation Format

Share Document