Identification of Bearing Defects in Hybrid Thrust Ball Bearings by Vibration Analysis

2015 ◽  
Vol 825-826 ◽  
pp. 844-851 ◽  
Author(s):  
Arne Ziebell ◽  
Oskar Schöppl ◽  
Roland Haubner ◽  
Thomas Konegger
Keyword(s):  
Vibration Analysis ◽  
Relevant Information ◽  
Optimal Operation ◽  
Ball Bearings ◽  
Test Rig ◽  
Successful Operation ◽  
Bearing Defects ◽  
The Status ◽  
Key Aspects

Hybrid ball bearings, consisting of metallic washers in combination with ceramic bearing balls, feature a variety of significant advantages in comparison to standard steel bearings, including mechanical properties and reduced friction during operation. Key aspects for a successful operation are a prevention of defects of both balls and washers, as well as the knowledge of critical and optimal operation parameters. This relevant information can be obtained through test rig trials, where vibration analysis has found to be a versatile and efficient tool for the characterization of the operational status. In this contribution, hybrid thrust ball bearings with Si3N4 balls are investigated. After an introduction of defined damages in different parts of the bearing, test rig trials were conducted, and the vibration behavior during operation was compared to new, unused bearings. The characteristic vibrational frequencies, obtained through a variety of software-based filter and analysis algorithms, were correlated with materialographic investigations of failed bearings. The proposed method was shown to yield valuable information about damage morphologies and, subsequently, about the status of the bearing during operation.

Effect of the Denoising on Acoustic Emission Signals

2010 ◽  
Vol 132 (3) ◽  
Author(s):  
X. Chiementin ◽  
D. Mba ◽  
B. Charnley ◽  
S. Lignon ◽  
J. P. Dron
Keyword(s):  
Acoustic Emission ◽  
Defect Detection ◽  
Vibration Analysis ◽  
The Self ◽  
Adaptive Noise Cancellation ◽  
Test Rig ◽  
Bearing Defects ◽  
Bearing Defect ◽  
Adaptive Noise ◽  
Statistical Indicators

The acoustic emission (AE) technology is growing in its applicability to bearing defect diagnosis. Several publications have shown its effectiveness for earlier detection of bearing defects than vibration analysis. In the latter instance, detection and monitoring of defects can be achieved through temporal statistical indicators, which can further be improved by application of denoising techniques. This paper investigates the application of temporal statistical indicators for AE detection of bearing defects on a purposely built test-rig and assesses the effectiveness of various denoising techniques in improving sensitivity to early defect detection. It is concluded that the denoising methods offer significant improvements in identifying defects with AE, especially the self-adaptive noise cancellation method.

Modelling and Validation of a Rotor System With Ball Bearings

2010 ◽  
Author(s):  
Onur Cakmak ◽  
Kenan Y. Sanliturk
Keyword(s):  
Experimental Data ◽  
Theoretical Model ◽  
Ball Bearing ◽  
Ball Bearings ◽  
Test Rig ◽  
Transform Method ◽  
Order Tracking ◽  
Bearing Defects ◽  
Gyroscopic Effects ◽  
Short Time

In this paper, a dynamic model of a rotor-ball bearing system is developed in Msc. ADAMS commercial software. Contacts between the balls and the rings are modelled according to Hertzian theory. The bearing model is capable of representing the effects of bearing defects and internal clearances. When they are coupled with the rotor structures, bearings without any defect can also cause excessive vibrations due to the resonance characteristics of the system. In order to demonstrate these characteristics the rotor itself is modelled as a flexible shaft and a disc positioned at the free end of the shaft. The rotor-ball bearing model developed here is capable of representing the gyroscopic effects and the behaviour of the system under different unbalance conditions. Various case studies are performed and Campbell diagrams are obtained by using short-time Fourier transform method. A test rig consisting of two ball bearings, a shaft and a disc is also designed and developed so as to validate the theoretical model using experimental data. The test rig is developed in such a way that all of the elements are easy to assemble/disassamble, allowing quick observation of the system’s dynamic behaviour for different parameters including imbalance, internal clearance and bearing defects. Modal analysis and order tracking analysis were carried out using the test rig. Both the modal results and Campbell diagrams obtained using experimental data are compared with their theoretical counterparts. In the light of the experimental data, the theoretical model is validated for the purpose of further analyses and research.

scholarly journals Time-Domain Based Quantification of Surface Degradation for Better Monitoring of the Health Condition of Ball Bearings

Vibration ◽  
2018 ◽  
Vol 1 (1) ◽  
pp. 172-191
Author(s):  
Ayman Salem ◽  
Abdelrahman Aly ◽  
Sadok Sassi ◽  
Jamil Renno
Keyword(s):  
Time Domain ◽  
Health Condition ◽  
Second Phase ◽  
Ball Bearings ◽  
Test Rig ◽  
Bearing Defects ◽  
Defect Growth ◽  
Rolling Element ◽  
Innovative Solution ◽  
The Time Domain

This research aims to analyze the vibration response of damaged rolling element bearings experimentally and to assess their degree of degradation by examining parameters extracted from the time domain. This task was accomplished in three phases. In the first phase, a test rig was carefully designed and precisely manufactured. In particular, an innovative solution for rapidly mounting and dismounting bearings on the supporting shaft was tested and used successfully. In the second phase, a specific technique of seeding defects inside the ball bearings was developed. In the last phase, damaged bearings (and healthy ones serving as a reference) were installed on the test rig, and different vibration measurements were taken. The results obtained from this work show that different parameters could be extracted from the time domain. In addition to the six common indicators (peak, root mean square, crest factor, kurtosis value, impulse factor, and shape factor), four hybrid new ones have been proposed (Talaf, Thikat, Siana and, Inthar). The experimental results confirm the well-known efficiency of kurtosis in the detection of bearing defects. However, the newly proposed parameters were found to be more responsive to defect growth.

scholarly journals Ultrafiltration Method for Plasma Protein Binding Studies and Its Limitations

Processes ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 382
Author(s):  
Camelia-Maria Toma ◽  
Silvia Imre ◽  
Camil-Eugen Vari ◽  
Daniela-Lucia Muntean ◽  
Amelia Tero-Vescan
Keyword(s):  
Protein Binding ◽  
Plasma Protein Binding ◽  
Plasma Protein ◽  
Specific Binding ◽  
Critical Role ◽  
Volume Ratio ◽  
Binding Studies ◽  
Experimental Conditions ◽  
Key Aspects

Plasma protein binding plays a critical role in drug therapy, being a key part in the characterization of any compound. Among other methods, this process is largely studied by ultrafiltration based on its advantages. However, the method also has some limitations that could negatively influence the experimental results. The aim of this study was to underline key aspects regarding the limitations of the ultrafiltration method, and the potential ways to overcome them. The main limitations are given by the non-specific binding of the substances, the effect of the volume ratio obtained, and the need of a rigorous control of the experimental conditions, especially pH and temperature. This review presents a variety of methods that can hypothetically reduce the limitations, and concludes that ultrafiltration remains a reliable method for the study of protein binding. However, the methodology of the study should be carefully chosen.

scholarly journals Copy Number Variation and Rearrangements Assessment in Cancer: Comparison of Droplet Digital PCR with the Current Approaches

2021 ◽  
Vol 22 (9) ◽  
pp. 4732
Author(s):  
Vincenza Ylenia Cusenza ◽  
Alessandra Bisagni ◽  
Monia Rinaldini ◽  
Chiara Cattani ◽  
Raffaele Frazzi
Keyword(s):  
Digital Pcr ◽  
Genetic Alterations ◽  
Droplet Digital Pcr ◽  
Molecular Oncology ◽  
Therapeutic Choice ◽  
Golden Standard ◽  
Number Variation ◽  
Key Aspects

The cytogenetic and molecular assessment of deletions, amplifications and rearrangements are key aspects in the diagnosis and therapy of cancer. Not only the initial evaluation and classification of the disease, but also the follow-up of the tumor rely on these laboratory approaches. The therapeutic choice can be guided by the results of the laboratory testing. Genetic deletions and/or amplifications directly affect the susceptibility or the resistance to specific therapies. In an era of personalized medicine, the correct and reliable molecular characterization of the disease, also during the therapeutic path, acquires a pivotal role. Molecular assays like multiplex ligation-dependent probe amplification and droplet digital PCR represent exceptional tools for a sensitive and reliable detection of genetic alterations and deserve a role in molecular oncology. In this manuscript we provide a technical comparison of these two approaches with the golden standard represented by fluorescence in situ hybridization. We also describe some relevant targets currently evaluated with these techniques in solid and hematologic tumors.

Untersuchungen zum Käfigrasseln bei Spindellagern*/Cage rattling analysis in spindle ball bearings

2016 ◽  
Vol 106 (01-02) ◽  
pp. 65-71
Author(s):  
E. Abele ◽  
L. Holland ◽  
J.-N. Burbach
Keyword(s):  
Behavior Analysis ◽  
Vibration Analysis ◽  
Ball Bearings ◽  
Negative Effects ◽  
Bearing Behavior

Instabile Käfigbewegungen wie das bekannte „Käfigrasseln“ können sich auf das Wälzlagerverhalten negativ auswirken. Die Analyse des Käfigrasselns ist daher essentiell, um das Phänomen besser verstehen und schließlich Maßnahmen ableiten zu können sowie instabile Bewegungszustände zu vermeiden. Dieser Beitrag stellt Schwingungsanalysen zur Untersuchung des Käfigrasselns vor.   Unstable cage movements, e.g. cage rattling, may have negative effects on bearing behavior. Analysis of cage rattling is essential to understand the phenomenon and to give recommendations for preventing unstable movements. This paper presents methods for vibration analysis in order to investigate cage rattling.

scholarly journals ASSESSING THE CANOPY INTEGRITY USING CANOPY DIGITAL IMAGES IN SEMIDECIDUOUS FOREST FRAGMENT IN SÃO CARLOS - SP- BRAZIL1

2017 ◽  
Vol 41 (5) ◽  
Author(s):  
Thiago Yamada ◽  
Emerson Carlos Pedrino ◽  
João Juares Soares ◽  
Maria do Carmo Nicoletti
Keyword(s):  
Digital Image Analysis ◽  
Digital Images ◽  
Research Work ◽  
Canopy Structure ◽  
Canopy Cover ◽  
Relevant Information ◽  
Canopy Closure ◽  
Forest Fragment ◽  
Semideciduous Forest

ABSTRACT It is well-known that conducting experimental research aiming the characterization of canopy structure of forests can be a difficult and costly task and, generally, requires an expert to extract, in loco, relevant information. Aiming at easing studies related to canopy structures, several techniques have been proposed in the literature and, among them, various are based on canopy digital image analysis. The research work described in this paper empirically compares two techniques that measure the integrity of the canopy structure of a forest fragment; one of them is based on central parts of canopy cover images and, the other, on canopy closure images. For the experiments, 22 central parts of canopy cover images and 22 canopy closure images were used. The images were captured along two transects: T1 (located in the conserved area) and T2 (located in the naturally disturbance area). The canopy digital images were computationally processed and analyzed using the MATLAB platform for the canopy cover images and the Gap Light Analyzer (GLA), for the canopy closure images. The results obtained using these two techniques showed that canopy cover images and, among the employed algorithms, the Jseg, characterize the canopy integrity best. It is worth mentioning that part of the analysis can be automatically conducted, as a quick and precise process, with low material costs involved.

Experimental Characterization of a Swirl Stabilized MGT Combustor

2015 ◽  
Author(s):  
T. O. Monz ◽  
M. Stöhr ◽  
W. O’Loughlin ◽  
J. Zanger ◽  
M. Hohloch ◽  
...  
Keyword(s):  
Flow Field ◽  
Flow Pattern ◽  
Flame Stabilization ◽  
Main Stage ◽  
Exhaust Gas ◽  
Test Rig ◽  
Gas Emissions ◽  
Preheating Temperature ◽  
Exhaust Gas Emissions

A swirl stabilized MGT combustor (Turbec T100) was operated with natural gas and was experimentally characterized in two test rigs, a pressurized and optically accessible MGT test rig and an atmospheric combustor test rig. For the detailed characterization of the combustion processes, planar OH-PLIF and simultaneous 3D-stereo PIV measurements were performed in the atmospheric combustor test rig. Flow fields, reaction zones and exhaust gas emissions are reported for a range of pressure scaled MGT load points. Parameter studies on combustor inlet conditions (e.g. air preheating temperature, air and fuel mass flow rates and fuel split) were conducted in the atmospheric combustor test rig. From the parameters studies the fuel split between the pilot and the main stage and the air preheating temperature were found to have the biggest impact on the flame shape, flame stabilization and exhaust gas emissions. The measurements of the ATM test rig are compared with measurements of the pressurized MGT test rig with and without an optically accessible combustion chamber. Opened and closed conical flame and flow pattern were found in both test rigs. Reasons for the two flame and flow pattern are supposed to be the interaction of pilot stage combustion and flow field and the interaction of the dilution air with the combustion and the flow field. The results are discussed and compared with repect to a transferability of combustion characteristics from the ATM test rig to the MGT test rigs.

scholarly journals Clinically, what ought we to believe?

2018 ◽  
Vol 27 (1) ◽  
pp. 72-74 ◽  
Author(s):  
John D Little ◽  
Lorraine Davison ◽  
Robert D Little
Keyword(s):  
Randomised Controlled Trial ◽  
Controlled Trial ◽  
Relevant Information ◽  
Evidence Base ◽  
Social Interventions ◽  
Hierarchy Of Evidence ◽  
Differences Of Opinion ◽  
The Status ◽  
Randomised Controlled ◽  
Clinical Strategy

Objective: To question the status of the randomised controlled trial (RCT) in the hierarchy of evidence. Conclusions: The RCT provides important and clinically relevant information, particularly in psychopharmacology. However, and as with other methodologies, RCTs too are flawed and automatic abdication to their conclusions, especially in complex social interventions, is unwise. A clinical example with conflicting and polarising views, each with their evidence base, is described alongside a suggested clinical strategy for resolving differences of opinion.

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