scholarly journals A novel method for diagnosing rolling bearing surface damage by electric impedance analysis

2022 ◽  
Author(s):  
Georg Martin ◽  
Florian Michael Becker ◽  
Eckhard Kirchner
Keyword(s):  
Impedance Analysis ◽  
Surface Damage ◽  
Time Domain Analysis ◽  
Rolling Bearing ◽  
Domain Analysis ◽  
Frequency Domain Analysis ◽  
Rolling Bearings ◽  
Monitoring Method ◽  
Novel Method ◽  
Bearing Damage

This paper presents a novel condition monitoring method for rolling bearings, based on measuring the electric bearing impedance. The method can diagnose the presence of damage by frequency-domain analysis, and its extension along the raceway by time-domain analysis. The latter enables the assessment of the severity and the progression of bearing damage. A fatigue test shows that the occurrence of pittings in the bearing raceways causes characteristic peaks in the impedance signal, and that the duration of the peaks increases during damage progression. A second test series with artificial damage shows that the duration of the peaks depends on the bearing load and the length of the damage along the raceway and confirms the explanation hypothesis.

scholarly journals Analysis of Three-Phase Wye-Delta Connected LLC

Energies ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3606
Author(s):  
Jing-Yuan Lin ◽  
Chuan-Ting Chen ◽  
Kuan-Hung Chen ◽  
Yi-Feng Lin
Keyword(s):  
Frequency Domain ◽  
Time Domain ◽  
Operation Time ◽  
Time Domain Analysis ◽  
Domain Analysis ◽  
Frequency Domain Analysis ◽  
Complete Analysis ◽  
Plane Analysis ◽  
Analysis Methods ◽  
Three Phase

Three-phase wye–delta LLC topology is suitable for voltage step down and high output current, and has been used in the industry for some time, e.g., for server power and EV charger. However, no comprehensive circuit analysis has been performed for three-phase wye–delta LLC. This paper provides complete analysis methods for three-phase wye–delta LLC. The analysis methods include circuit operation, time domain analysis, frequency domain analysis, and state–plane analysis. Circuit operation helps determine the circuit composition and operation sequence. Time domain analysis helps understand the detail operation, equivalent circuit model, and circuit equation. Frequency domain analysis helps obtain the curve of the transfer function and assists in circuit design. State–plane analysis is used for optimal trajectory control (OTC). These analyses not only can calculate the voltage/current stress, but can also help design three-phase wye-delta connected LLC and provide the OTC control reference. In addition, this paper uses PSIM simulation to verify the correctness of analysis. At the end, a 5-kW three-phase wye–delta LLC prototype is realized. The specification of the prototype is a DC input voltage of 380 V and output voltage/current of 48 V/105 A. The peak efficiency is 96.57%.

The Effect of the EHD Pressure Spike on Rolling Bearing Fatigue

1987 ◽  
Vol 109 (3) ◽  
pp. 444-450 ◽  
Author(s):  
L. Houpert ◽  
E. Ioannides ◽  
J. C. Kuypers ◽  
J. Tripp
Keyword(s):  
Pressure Distribution ◽  
High Stress ◽  
Surface Damage ◽  
Rolling Bearing ◽  
Shear Stresses ◽  
Stress Concentrations ◽  
Surface Layers ◽  
Rolling Bearings ◽  
Life Model ◽  
Pressure Spike

A recently proposed fatigue life model for rolling bearings has been applied to the study of lifetime reduction under conditions conducive to microspalling. The presence of a spike in the EHD pressure distribution produces large shear stresses localized very close to the surface which may account for early failure. This paper describes a parametric study of the effect of such spikes. Accurate stress fields in the volume are calculated for simulated pressure spikes of different height, width and position relative to a Hertzian pressure distribution, as well as for different lubricant traction coefficients and film thicknesses. Despite the high stress concentrations in the surface layers, reductions in life predicted by the model are modest. Typically, the pressure spike may halve the life, with the implication that subsurface fatigue still dominates. In corroboration of this prediction, preliminary experimental work designed to reproduce microspalling conditions shows that microindents due to overrolling particles are a much more common form of surface damage than microspalling.

Pulse Wave Analysis of Traditional Chinese Medicine Based on Hemodynamics Principles**

2011 ◽  
pp. 194-203
Author(s):  
Rui Guo ◽  
Yiqin Wang ◽  
Haixia Yan ◽  
Fufeng Li ◽  
Jianjun Yan ◽  
...  
Keyword(s):  
Chinese Medicine ◽  
Traditional Chinese Medicine ◽  
Clinical Significance ◽  
Pulse Wave ◽  
Time Domain Analysis ◽  
Domain Analysis ◽  
Frequency Domain Analysis ◽  
Pulse Velocity ◽  
Reflection Coefficients ◽  
Feature Parameters

From the perspective of hemodynamics principles, the pressure pulse wave marked in the radial artery is the comprehensive result of pulse wave propagation and reflection in the arterial conduit. The most common pulse charts (also called pulse wave) obtained by Traditional Chinese Medicine (TCM) pulse-taking technique, if quantified and standardized, may become a universal and valuable diagnostic tool. The methods of feature extraction of TCM pulse charts currently involve time-domain analysis, frequency-domain analysis and time-frequency joint analysis. The feature parameters extracted by these methods have no definite clinical significance. Therefore, these feature parameters cannot essentially differentiate different types of TCM pulse. In this chapter, the harmonic analysis method was applied to analyze the common TCM pulse charts (plain pulse, wiry pulse, slippery pulse). Velocity and reflectivity coefficients of pulse were calculated. We found that wave velocities and reflection coefficients of different TCM pulse have different distributions. Furthermore, we studied the clinical significance of velocities and reflection coefficients. The result suggests that wave velocity and reflection coefficient are the feature parameters of TCM pulse with physiological and pathological significance, which can be used to interpret formation of Chinese medicine pulse. Our study reveals the mechanism of TCM pulse formation and promotes non-invasive TCM pulse diagnostic method.

Modelling of Electrohydraulic Systems with Transmission Lines using Modal Approximations

1988 ◽  
Vol 202 (3) ◽  
pp. 153-163 ◽  
Author(s):  
J Watton
Keyword(s):  
Transmission Lines ◽  
Method Of Characteristics ◽  
Digital Simulation ◽  
Time Domain Analysis ◽  
Domain Analysis ◽  
Frequency Domain Analysis ◽  
Specific Form ◽  
Lumped Parameter ◽  
Good Comparison ◽  
Distributed Friction

The method of modal approximation to the distributed friction transmission line functions via frequency-domain analysis is briefly discussed. A specific form is then derived which allows time-domain analysis to be easily pursued using a digital simulation package approach. The method is applied to a highly non-linear servo-valve controlled motor system and a good comparison between experiment and theory is shown. A comparison is also made with previous work using the method of characteristics, and natural frequency predictions are also compared with some common lumped parameter approximations.

scholarly journals A New Conceptual Design and Dynamic Analysis of a Spar-Type Offshore Wind Turbine Combined with a Moonpool

Energies ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3737 ◽  
Author(s):  
Thanh Dam Pham ◽  
Hyunkyoung Shin
Keyword(s):  
Wind Turbine ◽  
Bending Moment ◽  
Time Domain Analysis ◽  
Domain Analysis ◽  
Frequency Domain Analysis ◽  
Dynamic Responses ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Operational Conditions ◽  
Floating Offshore Wind Turbines

Floating offshore wind turbines promise to provide an abundant source of energy. Currently, much attention is being paid to the efficient performance and the economics of floating wind systems. This paper aims to develop a spar-type platform to support a 5-MW reference wind turbine at a water depth of 150 m. The spar-type platform includes a moonpool at the center. The design optimization process is composed of three steps; the first step uses a spreadsheet to calculate the platform dimensions; the second step is a frequency domain analysis of the responses in wave conditions; and the final step is a fully coupled simulation time domain analysis to obtain the dynamic responses in combined wind, wave, and current conditions. By having a water column inside the open moonpool, the system’s dynamic responses to horizontal and rotating motions are significantly reduced. Reduction of these motions leads to a reduction in the nacelle acceleration and tower base bending moment. On the basic of optimization processes, a spar-type platform combined with a moonpool is suggested, which has good performance in both operational conditions and extreme conditions.

Hydrostatic Stability and Global Performance Analysis for Set TLP

2016 ◽  
Author(s):  
R. H. Yuck ◽  
S. J. Kim ◽  
S. U. Sung ◽  
H. J. Kim ◽  
D. Y. Lee ◽  
...  
Keyword(s):  
Time Domain Analysis ◽  
Domain Analysis ◽  
Frequency Domain Analysis ◽  
Hydrodynamic Characteristics ◽  
Wave Load ◽  
Operational Conditions ◽  
Western Africa ◽  
Structural Reinforcement ◽  
Global Performance ◽  
Tendon Tension

SET (Samsung Enhanced hull for Tendon) TLP (Tension Leg Platform) has been designed as an innovative TLP hull form with optimized number of tendons compared to conventional TLP design. SHI (Samsung Heavy Industries) designed the SET TLP to have the minimized hull weight with narrow and thin pontoon which results in the less number of tendons without any outboard extension of column or pontoon. The SET TLP has 8 tendons which are evenly attached along with the octagonal shaped-ring pontoon. The unique shape of octagonal ring pontoon distributes the wave load and concentrated tendon loads in larger areas, which can minimize the structural reinforcement. To verify the feasibility of the proposed hull concept with regard to the hydrostatic/hydrodynamic characteristics and tendon design, the numerical analyses for the hydrostatic stability and global performance are carried out. Hydrostatic stability is investigated for all the possible loading cases such as float-off, wet transit, tendon installation and operational conditions, and the proper tank compartments are achieved for all the scenarios without using any temporary stability module. The global performance is validated for all the possible combinations of wave, swell, wind, current and/or squall for a site in Western Africa. Through the frequency-domain analysis and nonlinear time-domain analysis as well, the essential items such as the maximum offset/set-down/top tendon tension, minimum bottom tendon tension are examined and confirms that the certain design criteria of TLP operation are satisfied.

A Frequency Domain Analysis of Learning Control

1994 ◽  
Vol 116 (4) ◽  
pp. 781-786 ◽  
Author(s):  
C. J. Goh
Keyword(s):  
Frequency Domain ◽  
Time Domain ◽  
Linear Time ◽  
Planning Horizon ◽  
Time Domain Analysis ◽  
Learning Control ◽  
Domain Analysis ◽  
Frequency Domain Analysis ◽  
Convergence Criterion ◽  
The Time Domain

The convergence of learning control is traditionally analyzed in the time domain. This is because a finite planning horizon is often assumed and the analysis in time domain can be extended to time-varying and nonlinear systems. For linear time-invariant (LTI) systems with infinite planning horizon, however, we show that simple frequency domain techniques can be used to quickly derive several interesting results not amenable to time-domain analysis, such as predicting the rate of convergence or the design of optimum learning control law. We explain a paradox arising from applying the finite time convergence criterion to the infinite time learning control problem, and propose the use of current error feedback for controlling possibly unstable systems.

DETERMINING THE RESOURCE OF THE OUTER RING OF A ROLLING BEARING BASED ON SIGNAL REGISTRATION AND SIMULATION OF THE TIME DEPENDENCE OF ACOUSTIC EMISSION PARAMETERS

2020 ◽  
pp. 26-34
Author(s):  
V. V. Nosov ◽  
I. A. Pavlenko ◽  
A. P. Artyushchenko ◽  
E. V. Grigoriev
Keyword(s):  
Acoustic Emission ◽  
Time Dependence ◽  
Experimental Studies ◽  
Surface Damage ◽  
Rolling Bearing ◽  
Diagnostic Value ◽  
Outer Ring ◽  
Rolling Bearings ◽  
Useful Signal ◽  
Informative Signals

Traditionally, the problem of monitoring the condition of rolling bearings can be solved based on registration of control signals that occur when the bearing performs a kinematic function due to contact of surface damage which is accumulated and caused by the processes of friction, impact, heat generation, contact electrical interaction, generation of elastic vibrations from them, etc. Relative to the bearing function of bearings, the diagnostic value of such signals is quite low, since they depend on many factors that are not related to resource-determining processes and play a destabilizing role in establishing the connection between control parameters and condition. The solution of the problem must be carried out based on a systematic approach linking the control of the object with the main criterion of its performance. Since the cause of bearing failures is fatigue processes occurring in the material of their elements, the most promising methods are those based on the registration of signals associated with the restructuring of the structure and the accumulation of damage of the material, and in particular, the method of acoustic emission (AE) based on recording the phenomenon of waves of elastic radiation at loading. The development of the acoustic emission method for monitoring the state of rolling bearings is based on a multi-level model of the time dependence of AE parameters, and the control is based on the assessment of the intensity parameters of the resource-determining stage of uniform elastic fracture of representative structural elements of the material of the test object. AE informative signals are selected, and diagnostic parameters are determined at the interlevel transition from macro- to micro- and nano-level. The idea of the transitions is to select representative informative parameters and to trace the connection between them through AE strength indicators that can highlight a useful signal in conditions of high instability and heterogeneity of the accompanying processes. The experimental stup and the results of experimental studies of AE of rolling bearings with an artificially created defect on the surface of the outer ring are described, the results of control are compared with the results of the analysis of the stress-strain state around the created defect, the informative value of the concentration and kinetic index and the possibility of evaluating the resource based on it are shown.

A Portable Detecting and Analytic Instrument of Vibration Signal

2012 ◽  
Vol 442 ◽  
pp. 305-308
Author(s):  
Jian Wei Li ◽  
Ling Wang ◽  
Hong Mei Zhang
Keyword(s):  
Frequency Domain ◽  
Virtual Instrument ◽  
Vibration Signal ◽  
Time Domain Analysis ◽  
Domain Analysis ◽  
Frequency Domain Analysis ◽  
Time Frequency ◽  
Notebook Computer ◽  
Usb Bus ◽  
Data Acquisition Card

It is often needed in engineering that detecting and analyzing vibration signal of some equipment. To meet the requirement, a portable detecting and analytic instrument was designed using virtual instrument concept. In the instrument, notebook computer was used as the platform of hardware. Vibration signal was obtained by integrated piezoelectric acceleration sensor (DTS0104T), and was transferred to a notebook computer through data acquisition card (NI USB-6210) based on USB bus. The software, running on the notebook computer, was developed under LabVIEW. Vibration signal could be displayed on screen, recorded in disk or printed by printer, retrieved, and analyzed. The analysis functions of the instrument include: time-domain analysis, frequency-domain analysis, time-frequency domain analysis, and correlation analysis. The instrument is compact, portable, powerful, and with friendly interfaces, has broad application prospects.

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