Loading...
Search for:
bearing
0.013 seconds
Total 221 records
Defect size estimation in rolling element bearings using vibration time waveform
, Article Insight: Non-Destructive Testing and Condition Monitoring ; Volume 51, Issue 8 , 2009 , Pages 426-430 ; 13542575 (ISSN) ; Alandi Hallaj, A ; Rohani Bastami, A ; Eftekharnejad, B ; Charnley, B ; Mba, D ; Sharif University of Technology
2009
Abstract
In this paper a new approach to determine the size of defects in rolling element bearings is proposed. This approach is based on the statistical characteristics of the vibration signals generated by rolling element bearings. Although some traditional statistical parameters such as r.m.s. and kurtosis have some diagnostic capabilities, these parameters are not suitable for quantifying the defect size. The proposed new model was validated experimentally for both inner and outer race defects and it is concluded that the newly proposed model can determine the defect length of rolling bearings
A new method for detection of rolling bearing faults based on the Local Curve Roughness approach
, Article Polish Maritime Research ; Volume 18, Issue 2 , July , 2011 , Pages 44-50 ; 12332585 (ISSN) ; Bastami, A ; Sharif University of Technology
2011
Abstract
Detection of rolling bearing faults by vibration analysis is an important part of condition monitoring programs. In this paper a new method for detection of bearing defects based on a new concept of local surface roughness, is proposed. When a defect in the bearing grows then roughness of the defective surface increases and measurement of the roughness can be a good indicator of the bearing defect. In this paper a method of indirectly measuring surface roughness by using vibration signal is introduced. Several attached examples including both numerically simulated signals and actual experimental data show the effectiveness of the new, easy-to-implement method
Inaccessible rolling bearing diagnosis using a novel criterion for Morlet wavelet optimization
, Article JVC/Journal of Vibration and Control ; 2021 ; 10775463 (ISSN) ; Kiakojouri, A ; Addin Arghand, H ; Davoodabadi, A ; Sharif University of Technology
SAGE Publications Inc
2021
Abstract
The objective of this research is to diagnose an inaccessible rolling bearing by indirect vibration measurement. In this study, a shaft supported with several bearings is considered. It is assumed that the vibration for at least one bearing is not recordable. The purpose is to diagnose inaccessible bearing by the recorded data from the sensors located on the other bearings. To achieve this goal, the continuous wavelet transform is used to detect weak signatures in the available vibration signals. A new criterion for adjusting the scale parameter of continuous wavelet transform is proposed based on the amplitude of the bearing characteristic frequencies. In this criterion, the optimal scale...
Control of shaft vibrations on magnetic bearings using neural network and sliding mode controller
, Article Proceedings of the 7th Biennial Conference on Engineering Systems Design and Analysis - 2004, Manchester, 19 July 2004 through 22 July 2004 ; Volume 1 , 2004 , Pages 787-793 ; 0791841731 (ISBN); 9780791841730 (ISBN) ; Salarieh, H ; Sharif University of Technology
American Society of Mechanical Engineers
2004
Abstract
This article discusses a method for complete control of the dynamics of a rotating shaft on magnetic bearings under the effects of mass imbalance. The electromagnetic bearings used in this research are 2 four-pole bearing at the two ends of the rotor, which are actuated by differential currents. Full dynamic behavior of 3- dimensional rigid rotor and its effects on dynamic model are included. The effects of rotating mass unbalance are also included in the equations. The geometric couplings between electromagnetic forces of the coils are included as uncertainty. By using sliding mode controller and a neural network to estimate the system nonlinear-coupled equations, in a way suitable for...
Inaccessible rolling bearing diagnosis using a novel criterion for Morlet wavelet optimization
, Article JVC/Journal of Vibration and Control ; Volume 28, Issue 11-12 , 2022 , Pages 1239-1250 ; 10775463 (ISSN) ; Kiakojouri, A ; Arghand, H. A ; Davoodabadi, A ; Sharif University of Technology
SAGE Publications Inc
2022
Abstract
The objective of this research is to diagnose an inaccessible rolling bearing by indirect vibration measurement. In this study, a shaft supported with several bearings is considered. It is assumed that the vibration for at least one bearing is not recordable. The purpose is to diagnose inaccessible bearing by the recorded data from the sensors located on the other bearings. To achieve this goal, the continuous wavelet transform is used to detect weak signatures in the available vibration signals. A new criterion for adjusting the scale parameter of continuous wavelet transform is proposed based on the amplitude of the bearing characteristic frequencies. In this criterion, the optimal scale...
Design, Analysis and Manufacturing of Gas Foil Bearing
, M.Sc. Thesis Sharif University of Technology ; Akbari, Javad (Supervisor) ; Movahhedy, Mohammad Reza (Supervisor)
Abstract
Foil gas bearings are compliant surface, self-acting hydrodynamic bearings that use ambient gas as their working fluid. They do not require external pressurization and are typically constructed from several layers of sheet metal foils. In high-speed, high-temperature applications the GFB’s have the advantage of developing higher load capacities than with fixed geometry gas bearings. Since GFB’s have a complex structure consisting of a spring-like substructure with an overlying flexible surface, there exists a great variety of permutations on any given design. At current work presents a 1D model for GFB with couple solving Reynolds and Euler-Bernoulli beam equation. This mean top foil assume to...
Seat width requirement for skewed bridges under seismic loads
, Article Scientia Iranica ; Vol. 21, issue. 5 , 2014 , pp. 1471-1479 ; ISSN: 10263098 ; Bagheri, S ; Sharif University of Technology
Abstract
In this paper, the dynamic characteristics of skewed bridges are explored analytically. Closed form solutions for translational and torsional periods of free vibration and mode shapes are given for slab-girder skewed bridges. Moreover, the seismic displacement of the deck of skewed bridges is calculated using the response spectrum method and its skew term is compared with the requirement of AASHTO. The effects of seismic force resisting elements, such as elastomeric bearings and end diaphragms are included. It is shown that the skew term in AASHTO's equation can underestimate the seat width requirement for some bridges. A new skew term for the bridge seat width requirement is suggested
Simulation and optimization of a semi spherical air bearing
, Article ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE) ; Volume 7, Issue PARTS A, B, C, D , 2012 , Pages 153-159 ; 9780791845233 (ISBN) ; Shahiri, A ; Nikparto, A ; Sharif University of Technology
2012
Abstract
It is important to test the attitude control systems on satellites before they are launched in space. Traditionally this has been done by dropping the satellite, and firing the thrusters before the satellite makes a soft landing in a net. This method only allows a few seconds of testing and does not lend itself to the measurement of pointing accuracy. A better method is to mount the satellite on a spherical air bearing. In this paper behavior of a semi spherical air bearing is studied and analyzed in various conditions. These bearings are used in different applications such as simulation of approximately frictionless condition which is the satellite's situation in space. In this analysis...
Assessment of the vertical stiffness of elastomeric bearing due to displacement and rotation
, Article International Journal of Non-Linear Mechanics ; Volume 119 , 2020 ; Kazemi, M. T ; Mirhosseini, S. M ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
The vertical stiffness of elastomeric bearing is a dominant parameter of the base isolation design. Several empirical relations have been used to calculate the vertical stiffness of the elastomeric bearing systems, although, in certain conditions such as the presence of rotation, these relations are not accurate enough. In this paper, by using a nonlinear finite element program, the effect of rotation on the vertical stiffness investigated. It was observed that the vertical stiffness of the isolator could be increased or decreased depending on the amount of rotation and the value of lateral displacement limit. © 2019 Elsevier Ltd
New constrained initialization for bearing-only SLAM
, Article Proceedings - 2013 IEEE International Conference on Control System, Computing and Engineering, ICCSCE 2013 ; 2013 , Pages 95-100 ; 9781479915088 (ISBN) ; Arbabmir, M. V ; Asl, H. G ; Sharif University of Technology
2013
Abstract
In this paper we present a new landmark initialization technique for Bearing-Only Simultaneous Localization and Mapping (SLAM) algorithm. The initialization scheme is a type of the delayed constrained initialization method and is different from previous approaches. In our work, it is shown that the angle between sequential observations measured by a bearing-only sensor such as pan-tilt camera and the distance between the vehicle and landmark plays an important role in landmark localization accuracy. Considering this fact, a proper constrained function that utilizes the rotation angle of the camera is applied between multiple landmark location estimates and the best estimate is selected. The...
Rolling bearing fault detection by short-time statistical features
, Article Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering ; Volume 226, Issue 3 , 2012 , Pages 229-237 ; 09544089 (ISSN) ; Bastami, A. R ; Mba, D ; Sharif University of Technology
SAGE
2012
Abstract
Rolling element bearing fault diagnosis is a very important part of condition-based maintenance. In this article, a new method for detection of rolling element bearing defects is proposed. The method is based on the concept of the cyclostationarity of the vibration signal to find periodicity in statistical features of the vibration signal. Various statistical features are examined to find the best choice. Several case studies including inner race, outer race, and rolling element defects are investigated in this article. Comparison with the envelope analysis showed that the proposed method benefits from clearer defect frequency identification
Estimation of rolling bearing life with damage curve approach
, Article Polish Maritime Research ; Volume 18, Issue 3 , Jan , 2011 , Pages 66-70 ; 12332585 (ISSN) ; Rafsanjani, H ; Mehdi, B ; Sharif University of Technology
2011
Abstract
The ability to determine the bearing life time is one of the main purposes in maintenance of rotating machineries. Because of reliability, cost and productivity, the bearing life time prognostic is important. In this paper, a stiffness-based prognostic model for bearing systems is discussed. According to presumed model of bearing and fundamental of damage mechanics, damage curve approach is used to relate stiffness of vibratory system and bearing running life. Furthermore, using the relation between acceleration amplitude at natural frequency and stiffness, final relation between acceleration amplitude at natural frequency and running life time according to damage curve approach can be...
An investigation of contact angles in angular contact ball bearings accounting for high speed effects and preload
, Article SAE International Journal of Passenger Cars - Mechanical Systems ; Volume 2, Issue 1 , 2009 , Pages 780-790 ; 19463995 (ISSN) ; Zahedi, A ; Sharif University of Technology
Abstract
Angular contact ball bearings are the most commonly used types of bearings. Although simple in appearance, these bearings have a complicated and nonlinear behavior, and have significant effect on the dynamics of a rotating system. Accounting for high speed effects adds to the complexity of their behavior. The governing equations of the bearing amount to the solution of a set of nonlinear equations for each rolling element at each iteration, which represents a tedious and expensive solution. In this work, a simplified model for angular contact ball bearings under the action of arbitrary loading including high speed effects and preload is presented. The model considers five degrees of freedom...
Experimental study of rolling element bearing failure pattern based on vibration growth process
, Article Proceedings of the 29th European Safety and Reliability Conference, ESREL 2019, 22 September 2019 through 26 September 2019 ; 2020 , Pages 1179-1186 ; Behzad, M ; Ghodrati, B ; Taghizadeh Vahed, A ; Sharif University of Technology
Research Publishing Services
2020
Abstract
Rolling-element bearing (REB) Failure is one of the most common failure in rotary machines in industry. Therefore, this concern draws attention to the concept of diagnostic and the prediction of REB failure. The efficacy of vibration analysis in this area has led many researchers to focus on this topic in recent decades. Defective bearings such as fatigue, surface roughness, and corrosion can lead to disastrous accidents. Therefore, providing an algorithm for the detection and classification of bearing defects is valuable and useful. The prediction of the bearing's lifetime is important to ensure the planned production in an industrial unit. In this paper, different models for performance...
Prognostic of rolling element bearings based on early-stage developing faults
, Article 2nd World Congress on Condition Monitoring, WCCM 2019, 2 December 2019 through 5 December 2019 ; 2021 , Pages 333-342 ; 21954356 (ISSN); 9789811591983 (ISBN) ; Behzad, M ; Khodaygan, S ; Sharif University of Technology
Springer Science and Business Media Deutschland GmbH
2021
Abstract
Rolling element bearing (REB) failure is one of the general damages in rotating machinery. In this manner, the correct prediction of remaining useful life (RUL) of REB is a crucial challenge to move forward the unwavering quality of the machines. One of the main difficulties in implementing data-driven methods for RUL prediction is to choose proper features that represent real damage progression. In this article, by using the outcomes of frequency analysis through the envelope method, the initiated/existed defects on the ball bearings are identified. Also, new features based on developing faults of ball bearings are recommended to estimate RUL. Early-stage faults in ball bearings usually...
Experimental investigation of unbonded ordinary steel reinforced elastomeric bearings as an isolation system in bridges
, Article Structures ; Volume 32 , 2021 , Pages 604-616 ; 23520124 (ISSN) ; Khaloo, A ; Ehteshami Moeini, M ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
Reduction of large tensile stresses and cost-efficiency has made unbonded isolators an attractive option as an isolation system. Following this idea and the results obtained by various researchers, it is shown that unbonded steel-reinforced elastomeric bearings (SREBs), which are used and designed for non-seismic actions, have inherently acceptable characteristics in tolerating large shear deformations for a cost-effective isolation system and can provide improved structural performance. However, this capacity is neglected in the design process. The current article presents an experimental program to analyze the mechanical properties of steel-reinforced natural rubber bearings without the...
Stability Analysis of Rotor Bearing Systems via Lyapunov's Direct Method
, M.Sc. Thesis Sharif University of Technology ; Zohoor, Hassan (Supervisor)
Abstract
Due to the use of rotor dynamics, in the rotating systems such as pumps, turbines and machine tool spindle gained special significance in recent decades and a growing need for rotating machines with high speed, leading to extensive research in this area. Due to instability in the dynamics of these systems, check the stability of the rotor system has been given special emphasis, so that studies and research in terms of models and methods allocated to this topic. The project analyzed the stability of a rotor that includes an elastic shaft is placed on the bearings as it is objective. From point of modeling, the rotor is modeled using Timoshenko beam theory and the rotor mounted on bearing with...
Passive localization of stationary targets: In extremely noisy conditions and asymmetric paths
, Article ISPACS 2012 - IEEE International Symposium on Intelligent Signal Processing and Communications Systems ; 2012 , Pages 385-389 ; 9781467350815 (ISBN) ; Sharif University of Technology
Abstract
A new method for position determination of stationary targets from radio bearings, using triangulation, and based on the partial derivative analysis of bearing error has been proposed. Mathematical derivations have been carried out and a simulation illustrating the effectiveness of the method has been run. It turns out that, the method works best when the noise is excessively high and the traversed path is asymmetric. In such conditions, the method illustrates an error reduction of up to 5% with respect to the Least Square algorithm
Prognostics of rolling element bearings with the combination of Paris law and reliability method
, Article 2017 Prognostics and System Health Management Conference, PHM-Harbin 2017 - Proceedings, 9 July 2017 through 12 July 2017 ; 2017 ; 9781538603703 (ISBN) ; Addin Arghan, H ; Rohani Bastami, A ; Sharif University of Technology
Abstract
In this research, a combination of the physical model based on Paris law and probability method is proposed for remaining useful life prediction of rolling element bearings. Level crossing is used as a feature that represents a linear relationship with defect size. Considering this linear relationship and using Paris law, a new model has been developed for bearings that follow degradation pattern with two stages. In this pattern, a bearing starts working in the healthy condition. Then it starts slow degradation stage and finally it goes to fast degradation stage until it reaches to the failure threshold. Considering a normal distribution for transition point from the slow degradation to the...
Sensor runout compensation in active magnetic bearings via an integral adaptive observer
, Article Control Engineering Practice ; Volume 48 , 2016 , Pages 111-118 ; 09670661 (ISSN) ; Habibollahi, A ; Behzad, M ; Salarieh, H ; Mehdigholi, H ; Sharif University of Technology
Elsevier Ltd
Abstract
Sensor runout is one of the main sources of harmonic disturbances in active magnetic bearing systems. This type of the disturbance not only causes harmonic vibrations in the system but also changes the steady-state position of the axis of rotation from the geometric center of the AMB. In this paper, an integral adaptive observer is proposed to identify the dc and harmonic content of the sensor runout and to estimate the states of the system at the same time. The Lyapunov method is used to prove asymptotic stability of the proposed observer. Unlike the proportional observer which amplifies the measurement error, the sensor runout can be completely compensated when the states of the integral...