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- Cavitation (3)
- Active magnetic bearing (2)
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- Piezoelectric fields (2)
- Rotor health monitoring (2)
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- Stability (2)
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- Fluid film bearing (1)
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- Hydrodynamic Lubrication (1)
- Hydrodynamic journal bearing (1)
- Machine bearings (1)
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Articles 1 - 19 of 19
Full-Text Articles in Engineering
Magnetic Bearings For Non-Destructive Health Monitoring Of Rotating Machinery Supported In Conventional Bearings, M. Kasarda, D, Quinn, T. Bash, D. Inman, R. Kirk, Jerzy Sawicki
Magnetic Bearings For Non-Destructive Health Monitoring Of Rotating Machinery Supported In Conventional Bearings, M. Kasarda, D, Quinn, T. Bash, D. Inman, R. Kirk, Jerzy Sawicki
Dr. D Dane Quinn
This paper describes initial results from a project expanding the field of rotor health monitoring by using Active Magnetic Bearings (AMBs) as actuators for applying a variety of known force inputs to a spinning rotor in order to monitor and evaluate response signals resulting from these inputs on-line. Similar to modal analysis and other nondestructive evaluation (NDE) techniques which apply input signals to static structures in order to monitor responses; this approach allows for the measurement of both input and output response in a rotating system for evaluation. However, unlike these techniques, the new procedure allows for multiple forms of …
Analytical Solutions Of Piston Ring Lubrication Using Mass Conserving Cavitation Algorithm, Jerzy Sawicki, Biao Yu
Analytical Solutions Of Piston Ring Lubrication Using Mass Conserving Cavitation Algorithm, Jerzy Sawicki, Biao Yu
Jerzy T. Sawicki
A novel analytical approach for piston ring lubrication solution is presented by taking proper account of mass conservation in the cavitated region (JFO boundary conditions). A system of five nonlinear equations is employed to calculate such parameters as oil film thickness, frictional force, power loss, and oil flow rate. For an enclosed cavitation pattern in piston-ring assembly it was found, that JFO boundary conditions give much better accounting of the estimation of friction force, power loss and flow rate. To show the effectiveness of the undertaken approach, the widely accepted Jeng's approach (Jeng, 1992a) was selected, in which the pressure …
Static And Dynamic Analysis Of Bearings For Truck Brake Compressor, Biao Yu, Jerzy Sawicki, V. Dunaevsky
Static And Dynamic Analysis Of Bearings For Truck Brake Compressor, Biao Yu, Jerzy Sawicki, V. Dunaevsky
Jerzy T. Sawicki
Mobility method is used to analyze the steady-state performance of crankshaft and connecting rod bearings which are subjected to loads whose magnitude and direction both vary in time. The steady-state characteristics include journal center orbit, minimum film thickness, maximum film pressure, effective temperature, flow through the bearing, etc. To extract the stiffness and damping coefficients over the load cycle, linear analysis method based on a short-bearing approximation is employed. In addition, the oil flow through the main and connecting rod bearings is investigated. Sufficient lubrication conditions for these bearings are discussed. This combined analysis is supported by numerical simulations.
Experimental And Theoretical Rotordynamic Characteristics Of A Hybrid Journal Bearing, Jerzy Sawicki, R. Capaldi, M. Adams
Experimental And Theoretical Rotordynamic Characteristics Of A Hybrid Journal Bearing, Jerzy Sawicki, R. Capaldi, M. Adams
Jerzy T. Sawicki
This paper describes an experimental and theoretical investigation of a four-pocket,oil-fed, orifice-compensated hydrostatic bearing including the hybrid effects of journalrotation. The test apparatus incorporates a double-spool-shaft spindle which permitsindependent control over the journal spin speed and the frequencyof an adjustable-magnitude circular orbit, for both forward and backwardwhirling. This configuration yields data that enables determination of thefull linear anisotropic rotordynamic model. The dynamic force measurements weremade simultaneously with two independent systems, one with piezoelectric loadcells and the other with strain gage load cells. Theoreticalpredictions are made for the same configuration and operating conditionsas the test matrix using a finite-difference solver of …
Nonlinear Prediction Of Rotordynamic Coefficients For A Hydrodynamic Journal Bearing, Jerzy Sawicki, T.V.V.L. Rao
Nonlinear Prediction Of Rotordynamic Coefficients For A Hydrodynamic Journal Bearing, Jerzy Sawicki, T.V.V.L. Rao
Jerzy T. Sawicki
In the analysis of hydrodynamic journal bearings, linearized stiffness and damping coefficients are widely used for the evaluation of stability and dynamic response characteristics. Under given operating conditions, these coefficients vary along the locus of the orbital response, and are not valid at large amplitudes (40% of the bearing clearance) of the journal motion. The time history of journal bearing motion for large vibrations is accurately predicted herein using nonlinear (time-transient) analysis. This paper discusses the adequacy of bearing analysis based on linearized coefficients and presents the significance of variation of the coefficients under the dynamic conditions. A method to …
Analytical Solution Of Piston Ring Pack Lubrication For Truck Air Brake Compressor, Biao Yu, Jerzy Sawicki, V. Dunaevsky
Analytical Solution Of Piston Ring Pack Lubrication For Truck Air Brake Compressor, Biao Yu, Jerzy Sawicki, V. Dunaevsky
Jerzy T. Sawicki
This paper presents an analytical solution of piston ring pack lubrication for two-cylinder truck air brake compressor. A system of nonlinear equations with seven variables was developed to describe lubrication phenomena of the piston ring pack for both fully flooded and starvation conditions. The full mass conservation boundary conditions defined by JFO ([ 14 ],[ 15 ]) theory were employed for complete description of the cavitation algorithm with enclosed and open cavitation patterns. Impact of the piston ring design parameters such as offset, crown height, and tension on the oil transport, lubrication conditions and friction losses of the compressor were …
Stability Characteristics Of Herringbone Grooved Journal Bearings Incorporating Cavitation Effects, T.V.V.L. Rao, Jerzy Sawicki
Stability Characteristics Of Herringbone Grooved Journal Bearings Incorporating Cavitation Effects, T.V.V.L. Rao, Jerzy Sawicki
Jerzy T. Sawicki
Stabilitycharacteristics of the herringbone grooved journal bearings (HGJBs) are analyzedtaking into account cavitation of the fluid flow. The perturbedvalues of pressure and film thickness from a given equilibriumposition are substituted into the Elrod's universal equation, which considersmass conservation in the complete bearing geometry. In order toanalyze the herringbone groove configuration, the governing equations under steadyand perturbed states are transformed to a rectangular domain usingthe grid transformation techniques. It is assumed that under perturbedconditions, the cavitation extent in the bearing remains unchanged andthe pressure gradients are computed in the full film region.The linearized stiffness and damping coefficients are evaluated in thecomplete …
Linear Stability Analysis For A Hydrodynamic Journal Bearing Considering Cavitation Effects, T.V.V.L. Rao, Jerzy Sawicki
Linear Stability Analysis For A Hydrodynamic Journal Bearing Considering Cavitation Effects, T.V.V.L. Rao, Jerzy Sawicki
Jerzy T. Sawicki
The purpose of this paper is to present the two-dimensional linear stability analysis considering the fluid flow in both full film and cavitation regions for a plain cylindrical journal bearing. The Lund's infinitesimal perturbation procedure is applied to Elrod's universal equation for evaluation of unsteady pressure gradients. Based on JFO theory, the pressure distribution, film rupture, and reformation boundaries can be obtained using Elrod's universal equation, for a given operating position of the journal. In this work, it is assumed that for infinitesimal perturbation of a journal about the equilibrium position, the film rupture and film reformation boundaries are the …
Dynamic Coefficient Prediction In Multi-Lobe Journal Bearings Using A Mass Conservation Algorithm, T.V.V.L. Rao, Jerzy Sawicki
Dynamic Coefficient Prediction In Multi-Lobe Journal Bearings Using A Mass Conservation Algorithm, T.V.V.L. Rao, Jerzy Sawicki
Jerzy T. Sawicki
A numerical procedure incorporating cavitation modeling in the predication of dynamic coefficients for four multi-lobe bearings is presented. A first order perturbation solution of the density (or fractional film content) is obtained by using the Elrod universal equation. The Elrod algorithm conserves mass throughout the bearing and automatically predicts the full film and cavitation regions using a switch function. In this work, the cavitation boundary predicted under steady state is considered for calculation of four unsteady pressure gradients. Results of stiffness and damping coefficients are presented for four multi-lobe bearing configurations, viz., two-axial groove, elliptical, three-lobe and offset cylindrical bearing …
Magnetic Bearings For Non-Destructive Health Monitoring Of Rotating Machinery Supported In Conventional Bearings, M. Kasarda, D, Quinn, T. Bash, D. Inman, R. Kirk, Jerzy Sawicki
Magnetic Bearings For Non-Destructive Health Monitoring Of Rotating Machinery Supported In Conventional Bearings, M. Kasarda, D, Quinn, T. Bash, D. Inman, R. Kirk, Jerzy Sawicki
Jerzy T. Sawicki
This paper describes initial results from a project expanding the field of rotor health monitoring by using Active Magnetic Bearings (AMBs) as actuators for applying a variety of known force inputs to a spinning rotor in order to monitor and evaluate response signals resulting from these inputs on-line. Similar to modal analysis and other nondestructive evaluation (NDE) techniques which apply input signals to static structures in order to monitor responses; this approach allows for the measurement of both input and output response in a rotating system for evaluation. However, unlike these techniques, the new procedure allows for multiple forms of …
Stability Analysis Of Floating Ball Bearing, T.V.V.L. Rao, Jerzy Sawicki
Stability Analysis Of Floating Ball Bearing, T.V.V.L. Rao, Jerzy Sawicki
Jerzy T. Sawicki
Conventional disk drive motors supported on ball bearings (BBs) cause nonrepeatable runout (NRRO) due to the surface imperfections on balls and raceways. NRRO is a source of track misregistration between head and disk that inhibits high track density in a hard disk drive. Fluid dynamic bearings with herringbone grooves either on the rotating or stationary surfaces are a suitable replacement for conventional ball bearings. Herringbone grooved bearings have considerably lower noise level than ball bearings and have better stability compared to plain journal bearings at concentric operating position. However, herringbone-grooved patterns are difficult to manufacture because groove depth is of …
Wear Behavior Of Tini And Tini-Tic Clads Deposited By Tig Surfacing, Masoud Harooni, Morteza Shamanian, Alireza Fadaei Tehrani
Wear Behavior Of Tini And Tini-Tic Clads Deposited By Tig Surfacing, Masoud Harooni, Morteza Shamanian, Alireza Fadaei Tehrani
Masoud Harooni
This paper deals with the investigation of wear behavior of TiNi and TiNi-TiC clads applied to plain carbon steel by tungsten inert gas (TIG) surfacing process. In this regard, ball milled Ti-Ni and Ti-Ni-C powder mixtures were used as feedstock materials. The clad layers were investigated using X-ray diffractometery (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), hardness measurements and reciprocating wear tests. The results of microhardness measurements indicated that hardness values of TiNi-TiC composites were higher than those of TiNi by approximately 100HV. It was also shown that the wear behavior of TiNi-TiC clads was better than that …
Manufacturing Self-Assembled Coatings Of Micro- And Nano-Particles By Controlled Evaporation Of Drops And Thin Films, Junfeng Xiao, Rajneesh Bhardwaj, Daniel Attinger
Manufacturing Self-Assembled Coatings Of Micro- And Nano-Particles By Controlled Evaporation Of Drops And Thin Films, Junfeng Xiao, Rajneesh Bhardwaj, Daniel Attinger
Daniel Attinger
The engineered deposition of self-assembled coatings of micro- and nano-particles on solid surfaces has applications in photonic crystals, optoelectronic devices, sensors, waveguides and antireflective coatings. Besides lithographic, etching or vapor deposition methods, these coatings can be self-assembled on small (
Self-Assembly Of Colloidal Particles From Evaporating Droplets: Role Of Dlvo Interactions And Proposition Of A Phase Diagram, Rajneesh Bhardwaj, Xiaohua Fang, Ponisseril Somasundaran, Daniel Attinger
Self-Assembly Of Colloidal Particles From Evaporating Droplets: Role Of Dlvo Interactions And Proposition Of A Phase Diagram, Rajneesh Bhardwaj, Xiaohua Fang, Ponisseril Somasundaran, Daniel Attinger
Daniel Attinger
The shape of deposits obtained from drying drops containing colloidal particles matters for technologies such as inkjet printing, microelectronics, and bioassay manufacturing. In this work, the formation of deposits during the drying of nanoliter drops containing colloidal particles is investigated experimentally with microscopy and profilometry, and theoretically with an in-house finite-element code. The system studied involves aqueous drops containing titania nanoparticles evaporating on a glass substrate. Deposit shapes from spotted drops at different pH values are measured using a laser profilometer. Our results show that the pH of the solution influences the dried deposit pattern, which can be ring-like or …
Basins Of Attraction Of Tapping Mode Atomic Force Microscopy With Capillary Force Interactions, Nicole N. Hashemi, Reza Montazami
Basins Of Attraction Of Tapping Mode Atomic Force Microscopy With Capillary Force Interactions, Nicole N. Hashemi, Reza Montazami
Nastaran Hashemi
We perform a large number of simulations over a wide range of system parameters to approximate the basins of attraction of steady oscillating solutions. We find that the basins of attraction vary as a function of system parameters and initial conditions. For large equilibrium separations, the basin of attraction is dominated by the low-amplitude solution. The location of the fixed point is shifted toward the higher values of instantaneous displacement and velocity for larger equilibrium separations. We show that the basin of attraction in the neighborhood of the fixed point is dominated by low-amplitude solutions as relative humidity is increased.
Gtaw ايجادشده با روش جوشکاری Tini-Tic و Tini بررسی ريزساختاری پوشش, Masoud Harooni, Morteza Shamanian, Alireza Fadaei Tehrani
Gtaw ايجادشده با روش جوشکاری Tini-Tic و Tini بررسی ريزساختاری پوشش, Masoud Harooni, Morteza Shamanian, Alireza Fadaei Tehrani
Masoud Harooni
هدف از انجام اين پژوهش بهبود سختي سطحي و ريزساختار فولاد ساده کربنی از نوع 52 و مقايسه ريز ساختار اين دو با هم GTAW ايجاد شده به روش جوشکاری TiNi-TiC و TiNi پوششی از بترتيب با نسبت استوکيومتری مساوي و نسبت ۲۰ Ti-Ni-C و Ti-Ni است. بدين منظور مخلوط پودری به طور جداگانه توسط روش فعال سازی مکانيکی فعال شد و سپس بر سطح TiC درصد تقويت کننده به ضخامت ۱ ميليمتر پيش نشانده شده با استفاده از روش جوشکاری قوسی St نمونه های فولادی 52 تنگستن- گاز ذوب و با فلز پايه امتزاج يافته است. جهت بررسي نوع …
Design And Development Of Orifice-Type Aerostatic Thrust Bearing, Jitendra P. Khatait
Design And Development Of Orifice-Type Aerostatic Thrust Bearing, Jitendra P. Khatait
Jitendra P Khatait
Air bearings are extensively used in precision machines and equipment in recent years. Unlike conventional bearings, there is no physical contact between the sliding surfaces. The moving surface can glide smoothly on the other surface, minimising the control effort to achieve high accuracy and precision. Analytical study was carried out avoiding complexities in the formulation. The governing parameters were kept at a minimum. This helped in easy understanding of the dynamics and performance behavior of the air bearings. A simple design methodology was also developed to assist in the design or the selection process of the bearing. Finally, a three-dimensional …
Piezoelectric In Situ Transmission Electron Microscopy Technique For Direct Observations Of Fatigue Damage Accumulation In Constrained Metallic Thin Films, Xiaoli Tan, T. Du, J.K. Shang
Piezoelectric In Situ Transmission Electron Microscopy Technique For Direct Observations Of Fatigue Damage Accumulation In Constrained Metallic Thin Films, Xiaoli Tan, T. Du, J.K. Shang
Xiaoli Tan
A piezoelectricin situtransmission electron microscopy(TEM) technique has been developed to observe the damage mechanism in constrained metallic thin films under cyclic loading. The technique was based on the piezoelectric actuation of a multilayered structure in which a metallic thin film was sandwiched between a piezoelectric actuator and a silicon substrate. An alternating electric field with a static offset was applied on the piezoelectric actuator to drive the crack growth in the thin metallic layer while the sample was imaged in TEM. The technique was demonstrated on solder thin films where cavitation was found to be the dominant fatigue damage mechanism.
In Situ Transmission Electron Microscopy Study Of Electric-Field-Induced Microcracking In Single Crystal Pb(Mg1/3nb2/3)O3–Pbtio3, Z. Xu, Xiaoli Tan, P. Han, J.K. Shang
In Situ Transmission Electron Microscopy Study Of Electric-Field-Induced Microcracking In Single Crystal Pb(Mg1/3nb2/3)O3–Pbtio3, Z. Xu, Xiaoli Tan, P. Han, J.K. Shang
Xiaoli Tan
In this letter, we report in situ transmission electron microscopy (TEM) study of effect of a cyclic electric field on microcracking in a single crystal piezoelectric 0.66Pb(Mg1/3Nb2/3)O3–0.34PbTiO3. A TEM heating stage was modified to permit the in situ application of an electric field on the TEM sample surface. Microcrack initiation from a fine pore under an applied cyclic electric field was directly observed in the piezoelectric single crystal. Experimental procedures for in situ TEM studies were described.