Academic literature on the topic 'ECCENTRICITY SIMULATION'

ABSTRACT We present the results of a 3D global magnetohydrodynamic (MHD) simulation of an AM CVn system that was aimed at exploring eccentricity growth in the accretion disc self-consistently from a first principles treatment of the MHD turbulence. No significant eccentricity growth occurs in the simulation. In order to investigate the reasons why, we ran 2D alpha disc simulations with alpha values of 0.01, 0.1, and 0.2, and found that only the latter two exhibit significant eccentricity growth. We present an equation expressing global eccentricity evolution in terms of contributing forces and use it to analyse the simulations. As expected, we find that the dominant term contributing to the growth of eccentricity is the tidal gravity of the companion star. In the 2D simulations, the alpha viscosity directly contributes to eccentricity growth. In contrast, the overall magnetic forces in the 3D simulation damp eccentricity. We also analysed the mode-coupling mechanism of Lubow, and confirmed that the spiral wave excited by the 3:1 resonance was the dominant contributor to eccentricity growth in the 2D α = 0.1 simulations, but other waves also contribute significantly. We found that the α = 0.1 and 0.2 simulations had more relative mass at larger radii compared to the α = 0.01 and 3D MHD simulation, which also had an effective α of 0.01. This suggests that in 3D MHD simulations without sufficient poloidal magnetic flux, MRI turbulence does not saturate at a high enough α to spread the disc to large enough radii to reproduce the superhumps observed in real systems.

With the increase request of strip quality, the roller eccentricity has become the important factor of influencing product quality. On the practical model of Cold-rolling Mill of 300, this paper establishes eccentricity compensation control practice of Cold-rolling Mill of 300 which applies wavelet transform method. Based on mufti-resolution decomposition of roll force signal by use of wavelets, eccentricity signals are separated from disturbances and noise，and self-optimization is employed to real-time control the roller eccentricity. The results show that the method is effective.

For the dispersity of particles in the process of ceramics dry granulating, simulating the effect of spindle eccentricity on it based on the Euler-Euler model. Simulation results show that the volume fraction of particles in the granulating chamber were 52%, 53%, 51% when the spindle eccentricity were 15mm, 25mm, 35mm. For particles distribute in the region of packing density above 0.4kg/m3 , the volume fraction in the granulating chamber were 11%, 3%, 7%. Therefore, spindle eccentricity has little effect on the whole the volume fraction of particles, but the effect on particles distribute in the region of packing density above 0.4kg/m3 is larger .Particles dispersity is best in the process of granulating when spindle eccentricity is 30mm.

This paper was concerned with theoretical analysis and the static characteristics of the journal bearing lubricated with magnetic fluid. A general Reynolds equation based on magnetic fluid model is obtained, which can be easily extended to other non-Newtonian fluids and this equation can provide theoretical basis for hydrodynamic analysis of magnetic fluid journal bearings. For the case of static loaded magnetic journal bearings, the influence of magnetic fluid effects on the lubrication performance is studied under various eccentricity ratios, magnetic intensity and concentration. The numerical results show that: with the increasing of concentration, the bearing capacity is obviously increased; the increase magnitude is larger when the eccentricity ratio is large. Under the effect of magnetic field, the bearing capacity increasing with the increasing of magnetic field intensity. When the eccentricity is small, the side leakage is highly decreased. It can be completely eliminate by appropriately designing the bearing geometry and the magnetic field which can’t be existed in normal journal bearings.

The problem of roll eccentricity has become one of important factors to affect the quality of strips as downstream industries require improvement of the strip quality. Reducing thickness control precision as little as possible is incompatible with restraining roll eccentricity perturbations on the requirement of the deadband size for the deadband drift method (DDM) with fixed deadband width. Therefore, the GM-AGC system in hot finishing mill of an aluminum plant uses the dynamic deadband eccentricity filter (DDEF) whose deadband width varies with the amplitude of the roll eccentricity signal. The operating principle of DDEF was introduced according to the characteristic of roll eccentricity signal. Based on the theory of DDEF, simulation was carried out. Comparing with DDM, the simulation result shows that DDEF can keep a balance between less lowering thickness control precision and restraining roll eccentricity perturbations on the requirement of the deadband size. Moreover, the deadband width of DDEF is capable to fit the variations in the frequency and amplitude of the synthetic roll eccentricity signal to restrain the misoperation of GM-AGC system.

The paper deals with the issue of eccentricity in the technological node of the piercing press, under selected conditions, which result from the possibilities of production in the conditions of ŽP a.s. These conditions were verified and adapted to the rolling process. This process consisting of individual technological nodes on the rolling mill, in which eccentricity is created on the piercing press and the following steps eliminate it in other technological nodes. For quality analysis of manufacturing tubes using numerical simulation, it is necessary to know the actual state of eccentricity creation on the rolling mill. A numerical simulation of piercing under different input conditions was used (software DEFORM-3D) and was performed for several different charge states before entering onto the piercing press. The eccentricity itself has a significant effect on the resulting geometric quality of the tubes.

The roll eccentricity signal is a weak and complex periodic signal that is difficult to be identified. To improve the detection accuracy of the roll eccentricity signal and to compensate effectively, this study proposed a roll eccentricity signal detection method by combining the sparse fast Fourier transform (SFFT) and the iterative adaptive approach (IAA). The proposed method can rapidly determine the frequency range of the roll eccentricity signal by using the SFFT. Then, it divides the frequency range into several small frequency bands. In each small frequency band, the frequency, amplitude, and phase angle of each harmonic component of the roll eccentricity signal were estimated by using IAA. The simulation results show that the proposed method can find all frequency components, and the frequency estimation accuracy is higher than 99.88%. Finally, the engineering application of this method and the eccentricity compensation control were investigated. In engineering applications, the proposed method can reduce the thickness fluctuation of the finished strip by 89.2%, and the product quality is improved significantly. The simulation results and engineering experiments show that the proposed method has an excellent effect on detecting and compensating roll eccentricity signals.

This paper investigates the influence of wheel eccentricity on vertical vibration of suspended monorail vehicle based on experiment and simulation. Two sets of tests are conducted in the first Chinese suspended monorail, and the tested acceleration is analyzed and exhibited. A multibody dynamic model of the suspended monorail vehicle is established to simulate the vertical vibration of car body excited by wheel eccentricity. The results show that there are three factors which may cause an abnormal vibration considering the track and the vehicle system. The influence of wheel eccentricity on the car body vibration was firstly analyzed. Simulated acceleration of car body has a great accordance with test. The wheel eccentricity could excite the resonance of car body at the speed of 21 km/h, and the vertical acceleration would increase considerably. Decreasing the secondary stiffness can effectively reduce the vertical vibration caused by wheel eccentricity, especially at the resonant speed. In the secondary test, the peak of car body acceleration at speed of 20 km/h is not appearing when only renewing the wheels, and the acceleration is decreasing obviously at the domain frequency. It is further determined that the abnormal vibration is mainly caused by the wheel eccentricity.

The study of eccentricity minimization in cylindrical products helps to reduce the mechanical vibrations and wear of related mechanical parts such as bearings, columns and gears which positively affects in maintenance costs savings and increasing production quality reliability. The main purpose of this paper is to investigate the effect of the eccentricity between the billet material and the die parts on the quality of the final product in the direct extrusion process. The input parameters to produce a cylindrical product shape are optimized in MINITAB based on Taguchi method and ANOVA. The selected material of the billet is the aluminium alloy AA2024, and the die material is Steel H13. The inputs parameters are the temperature, the die angle, the ram speed, and the presumed eccentricity. The finite element model of the process is simulated in DFORM-3D for providing the extrusion information such as the pressure, the effective stress and strain, the final product eccentricity, and the roundness error. The study is carried out on two cases of the presumed eccentricity in addition to a case of zero eccentricity. The single and multi-response optimizations are executed to obtain the optimum parameters for the minimum product eccentricity and roundness error.

The stiffness analysis method considering uncertainty parameters of frame hydraulic press with movable eccentricity loading in the early design stage was proposed. The mathematical analytical stiffness of the upper beam with movable eccentricity loading was built. The adaptive Monte Carlo Method was used to calculate the interval of the stiffness with random parameters. The result shows that the stiffness appears higher when the eccentricity increasing. The approach has been tested by measuring the stiffness of a 10000kN frame hydraulic press and a 15000kN frame hydraulic press.

It is generally assumed that the temperature in the inner part of the primordial nebula was too high to form and agglomerate ice bodies. Yet, water is present in most of the terrestrial planets of our solar system. To investigate the reason for this we concentrate on comets as a potential water deliverer to the inner planets. The data for this work is taken from 3D simulations of comet trajectories inside a gas-dust disk with embedded planet embryos. We have developed a MATLAB code that could read data files from these simulations containing orbital elements of the comets and planetary embryos. Comets experience inward migration due to friction with the remains of the disk. We study comets of four different sizes.      We find that smaller comets migrate faster and therefore spend less time in the inner solar system. Smaller comets are numerous and are therefore destroyed in greater numbers than the larger comets. Larger comets on the other hand slow their migration and spending much more time among inner planets they are more massive and produce more massive collisions with the inner planets than the smaller comets. Therefore are larger comets a more promising source of water delivery to the inner planets. In Studying individual collisions we observe that a typical interaction involves regular close encounters with the same embryo during periods of 100000 years or more before the two orbits intersect. This also tells us that with a large number of comets expected at this stage of solar system evolution the collective effect of comets on low-mass planetary embryos may be significant.

Le but principal de ce travail était d'optimiser le processus standard d'étirage des tubes de manière à contrôler l'excentricité, qui peut être la réduction ou l'augmentation de l'excentricité. Pour cette raison, l'inclinaison et / ou le déplacement ont été introduits respectivement dans le matrice et / ou le tube. Plusieurs tubes de matériaux différents - tels que le cuivre, l'aluminium, le laiton et l'acier - de différentes dimensions ont été étudiés. L’effet sur l'excentricité a été analysé en utilisant divers angles d'inclinaison, valeurs de déplacement ou combinaison d'inclinaison et de décalage. Tout en influençant et en contrôlant l'excentricité, l'évolution des contraintes résiduelles et de la texture due à l'inclinaison et / ou au décalage introduits ont été étudiées. L'autre objectif de ce travail était de développer un modèle FEM universel, afin d'obtenir les paramètres d'entrée requis, liés au matériau ou au processus ou aux deux. Ce modèle FEM a été utilisé pour accomplir la simulation du processus de formage du métal défini par l'utilisateur et pour analyser des situations plus complexes. À cet égard, un modèle de simulation multi-échelle a été développé à l'aide d'une méthode de simulation multi-échelle avec l'approche Integrated Computational Material Engineering
The main and foremost aim of this work was to optimize the standard tube drawing process in a way that the eccentricity can be controlled, which can be the reduction or increase of eccentricity. For this reason, tilting and/or shifting was introduced to the die and/or tube, respectively. Different tubes of varied materials, such as copper, aluminum, brass, and steel with different dimensions were investigated by various tilting angles, shifting values, or combination of tilting and shifting and their effect on the eccentricity was analyzed. Along influencing and controlling the eccentricity, the evolution of the residual stresses and texture due to the introduced tilting and /or shifting were investigated. The other aim of this work was to develop a universal FEM model, which can get the required or desired input parameters, which can be material-related or process related or both, and perform the simulation of the user-defined metal forming process and therewith analyze more complex situations. In this regard, a simulation model was developed using a multiscale simulation method with Integrated Computational Material Engineering approach

Tesis de maestría
Using non-linear analyses and Monte Carlo simulations, a simplified accidental-torsion design procedure is evaluated. The design procedure does not use an accidental eccentricity like the building codes do. For the evaluation, four reinforced concrete frame building models of four and seven stories are dynamically studied in the nonlinear range. The models are subjected to a set of five firm-soil, bidirectional seismic records. The design procedure is evaluated by comparing the ductility demands of both beams and columns for three conditions of each building model: a) the torsionally balanced model without accidental torsion (model TB), which establishes the reference values of ductility demands; b) the same nominal model but incorporating accidental torsion via the Monte Carlo method; and c) a model with amplified strength (model AS) according to the accidental-torsion design procedure to be evaluated. Results indicate that there is a probability smaller than 2.5% that accidental torsion can cause ductility demands approximately 20% to 25% larger than those of similar building models without accidental torsion. A comparison of ductility demands for the reference models without accidental torsion and those of models with accidental torsion and designed with the procedure that is evaluated, reveals that the design procedure is effective to control the effects of accidental torsion.

Tesis de maestría. Artículo técnico.
A comparative analysis between the responses obtained with two procedures that consider the accidental torsion on the dynamic nonlinear analysis of buildings is presented. The first one involves the use of typical values of accidental eccentricities used in design process. The second procedure involve the variation of parameters that incise in the accidental torsion by means Monte Carlo simulations. The comparison is performed from the responses obtained, measured in terms of concentrated inelastic deformations and lateral distortions. In the study two models of multi-level symmetrical buildings are considered. The CANNY-E program is used for the nonlinear dynamic analysis of the proposed structural models. The results suggest move the position of the center of mass a distance equal to 0.05b to consider the effect of accidental torsion on the dynamic nonlinear analysis of buildings
Consejo Nacional de Ciencia y Tecnología

[cat] Aquesta tesi és un recull del treball realitzat en els darrers quatre anys d’investigació enfocats a la producció de simulacions de relativitat numèrica de forats negres binaris en configuracions genèriques, així com a l’anàlisi de les ones gravitacionals extretes de dites simulacions, les seves conseqüències pel models de formes d’ones gravitacionals existents i les seves implicacions per a la cerca i l’estimació dels paràmetres d’aquests sistemes en la natura. Per començar, he estudiat la prescripció de paràmetres inicials en les simulacions de relativitat numèrica. Un problema ben conegut a relativitat numèrica és la dificultat d’obtenir simulacions de forats negres en òrbites quasi-circulars, degut a imprecisions en la generació de les dades inicials que provoquen òrbites quasi-el líptiques amb una excentricitat residual. El primer projecte d’aquesta tesi ha estat el desenvolupament d’un procediment iteratiu, senzill i computacionalment eficaç per a la reducció de l’excentricitat a simulacions de relativitat numèrica de forats negres binaris, veure Cap. 4. Amb aquest mètode s’han generat formes d’ona gravitacionals quasi-circulars amb una excentricitat negligible, e O 􀀀��� 10􀀀���4 , que han estat utilitzades pel nostre grup per generar models quasi-circulars de formes d’ona gravitacionals. La flexibilitat del mètode anterior permet no tan sols reduir l’excentricitat de les simulacions numèriques, sinó també augmentar-la. Aquest fet ha permès la generació d’un banc de més de 60 simulacions de relativitat numèrica amb excentricitat moderada e 0:5. Aquest ha estat el segon projecte d’investigació de la tesi, veure Cap. 5. Amb aquest grup de simulacions s’han generat formes d’ona híbrides pel mode dominant (2; 2) entre les ones obtingudes per la teoria post-Newtoniana i les de relativitat numèrica. A més, s’ha estimat les limitacions dels models quasi-circulars actuals per estimar paràmetres d’aquestes fonts. Els resultats obtinguts demostren que els models quasi-circulars de formes d’ona que inclouen modes subdominants redueixen el biaix en alguns paràmetres com la distància i el ràtio de massa, respecte a models sense modes subdominants. Per altra banda, durant el doctorat també s’han estudiat les limitacions de dues aproximacions utilitzades habitualment per models d’ona quasi-circulars amb espins precessants, veure Cap. 6. Aquestes dues aproximacions s’han analitzat emprant únicament simulacions de relativitat numèrica incloent modes subdominants. Els resultats obtinguts confirmen el bon funcionament de les aproximacions pels modes dominants (2; 2), mentre que pel modes subdominants s’observa una degradació important degut a diferent causes depenent del mode estudiat, per exemple, els modes (2; 1) són molt sensibles a les asimetries entre modes que les aproximacions negligeixen, mentre que els modes (4; 3) i (3; 2) pateixen mescla de modes en la part del decaïment de l’ona que les aproximacions no tenen en compte. Finalment, s’ha analitzat la sensibilitat de dos algorismes de cerca emprats per les col laboracions LIGO i Virgo durant el segon període d’observació O2 per detectar senyals completes d’ones gravitacionals procedents de binàries de forats negres eccèntriques, veure Cap. 7. En aquest treball preliminar s’ha quantificat l’impacte de l’excentricitat sobre dos algorismes de cerca: un codi de filtrat adaptat basat en el coneixement de la morfologia de la senyal, i un codi de cerca sense modelat. En aquest estudi s’estima per primera vegada la sensibilitat d’ambdós algorismes injectant senyals excèntriques calculades a partir de simulacions de relativitat numèrica incloent espins alineats amb el moment angular orbital del sistema. Els resultats obtinguts mostren una major degradació de la sensibilitat de l’algorisme de filtrat adaptat a mesura que l’excentricitat augmenta, mentre que la sensibilitat de l’algorisme sense modelat no es veu quasi afectada per l’increment de l’excentricitat, i per tant, es pot identificar aquest darrer com una eina robusta per a la detecció de senyals excèntriques.
[spa] Esta tesis recoge el trabajo realizado en los últimos cuatro años de investigación enfocados en la producción de simulaciones de relatividad numérica de agujeros negros binarios en configuraciones genéricas, así como en el análisis de las ondas gravitacionales extraídas de dichas simulaciones, sus consecuencias para los modelos de formas de ondas existentes y sus implicaciones para la búsqueda y la estimación de los parámetros de dichos sistemas en la naturaleza. Para empezar, he estudiado la prescripción de parámetros iniciales en las simulaciones de relatividad numérica. Un problema bien conocido en relatividad numérica es la dificultad de obtener simulaciones de agujeros negros en órbitas casi-circulares, debido a imprecisiones en la generación de los datos iniciales que provocan órbitas casi-elípticas con una excentricidad residual. El primer proyecto de esta tesis ha sido el desarrollo de un procedimiento iterativo, sencillo y computacionalmente eficaz para la reducción de la excentricidad en simulaciones de relatividad numérica de agujeros negros binarios, ver Cap. 4. Con este método se han generado formas de onda gravitacionales casi-circulares con una excentricidad negligible, e O 􀀀�� 10􀀀��4 , que han sido usadas por nuestro grupo para generar modelos de formas de onda casi-circulares. La flexibilidad del método anterior permite no solo reducir la excentricidad de las simulaciones numéricas, sino también aumentarla. Este hecho ha permitido la generación de un banco de más de 60 simulaciones de relatividad numérica con excentricidad moderada e 0:5. Este ha sido el segundo proyecto de investigación de la tesis, ver Cap. 5. Con este grupo de simulaciones he generado formas de onda híbridas para el modo dominante (2; 2) entre las ondas obtenidas a partir de la teoría post- Newtoniana y las de relatividad numérica. Además, con colaboradores he estimado las limitaciones de los modelos casi-circulares actuales para estimar los parámetros de estas fuentes. Los resultados obtenidos demuestran que los modelos casi-circulares de formas de onda que incluyen modos subdominantes reducen el sesgo en algunos parámetros como la distancia y el ratio de masa, respecto a los modelos sin modos subdominantes. Por otro lado, durante el doctorado también se han estudiado las limitaciones de dos aproximaciones utilizadas comúnmente para modelos de onda casi-circulares con espines precesantes, ver Cap. 6. Estas dos aproximaciones se han analizado usando únicamente simulaciones de relatividad numérica incluyendo modos subdominantes. Los resultados obtenidos confirman el buen funcionamiento de las aproximaciones para los modos dominantes (2; 2), mientras que para los modos subdominantes se observa una degradación importante debido a diferentes causas dependiendo del modo estudiado, por ejemplo, los modos (2; 1) son muy sensibles a las asimetrías entre modos que las aproximaciones negligen, mientras que los modos (4; 3) y (3; 2) padecen mezcla de modos en la parte del decaimiento de la onda que las aproximaciones no tienen en cuenta. Finalmente, con colaboradores he analizado la sensibilidad de dos algoritmos de búsqueda, utilizados por las colaboraciones LIGO y Virgo durante el segundo período de observación O2, para detectar señales completas de ondas gravitacionales procedentes de binarias de agujeros negros excéntricos, ver Cap. 7. En este trabajo preliminar se ha cuantificado el impacto de la excentricidad sobre dos algoritmos de búsqueda: un código de filtrado adaptado y un código de búsqueda sin modelado. En este estudio se estima por primera vez la sensibilidad de ambos algoritmos inyectando señales excéntricas calculadas a partir de simulaciones de relatividad numérica. Los resultados muestran una mayor degradación de la sensibilidad del algoritmo de filtrado adaptado a medida que aumenta la excentricidad, mientras que el algoritmo sin modelado no se ve casi afectado por el aumento de la excentricidad, y por tanto, se puede identificar este último como una herramienta robusta para la detección robusta de señales excéntricas.
[eng] This thesis gathers all the work done in my last four years of research focused on the production of numerical relativity simulations of generic binary black holes, as well as the analysis of the gravitational waveforms from these simulations and their implications for searches and parameter estimation on those systems. I have started studying the prescription of initial parameters in numerical relativity simulations. A well known problem in numerical relativity is the difficulty to obtain simulations of black holes orbiting in quasi-circular orbits due to inaccuracies of the initial data, which cause elliptical orbits with residual eccentricity. The first project of the thesis has been the development of a simple, iterative and computationally efficient procedure to reduce the eccentricity in binary black hole numerical relativity simulations, see Chap. 4. With this method we have produced quasi-circular waveforms with negligible eccentricity, e O 􀀀� 10􀀀�4 , which have been used in our group to generate quasi-circular waveform models. The flexibility of the previous method permits not only the reduction of the eccentricity, but also increasing it. Using this fact I have produced a data set of more than 60 numerical relativity simulations with moderate eccentricity e 0:5. This has been the second project of the thesis, see Chap. 5. Taking this set of simulations, with collaborators I have generated hybrid waveforms for the dominant (2; 2) mode between post-Newtonian and numerical relativity waveforms. Moreover, we have estimated the limitations of the current quasi-circular waveform models to estimate the parameters from those sources. We have found that the quasi-circular models which include higher order modes reduce the bias in some parameters like the mass ratio and luminosity distance, with respect to those models not including higher order modes. Furthermore, during the Ph.D. I have also studied the limitations of two approximations commonly used by precessing quasi-circular waveform models, see Chap. 6. These two approximations have been analysed using exclusively numerical relativity simulations including higher order modes. The results confirm the good performance of the approximations for the (2; 2) modes, while one observes a clear degradation for higher order modes due to different reasons depending on the considered mode. For instance, the (2; 1) modes are found to be very sensitive to asymmetries which the approximations neglect, while the (4; 3) and (3; 2) modes, have mode-mixing in the ringdown part which is not properly taken into account by the simple approximations. Finally, with collaborators I have analysed the sensitivity of two search pipelines, used by the LIGO and Virgo collaborations during the O2 Science Run, to the full gravitational wave signal of eccentric binary black holes, see Chap. 7. In this preliminary work we have quantified the impact of eccentricity on two search pipelines: a matched-filter and an unmodeled search algorithm. We have for the first time estimated the sensitivity of both algorithms injecting eccentric signals computed from numerical relativity simulations. The results show a larger degradation of the sensitivity of the matched-filter algorithm with increasing eccentricity, while the sensitivity of the unmodeled search algorithm remains barely unaffected to the increase of eccentricity, thus, we consider the latter one a robust tool to detect such eccentric signals.

碩士
國立成功大學
系統及船舶機電工程學系碩博士班
98
Owing to the gradual depletion of oil and a concern for environmental protection, motors have become the drive system of the future instead of the combustion engine. Among various types of motors, induction motors are often used due to their simple structure, fast reaction, and powerful propulsion force. Thus, the safe operation of motor vehicles is a major concern with the trends in the online fault monitor. However, the accuracy of online monitoring is the most difficult task. Based on statistics, the motor failures caused by electric and mechanical parts may occur mainly in stator, bearing and rotor. Among mechanical faults, 80% of relevant troubles may cause the phenomenon of air-gap eccentricity, leading to the power factor decreasing, motor vibrations, power losses and enlargement of the fault area. Particularly, it may result in the rotor and stator sides to chaft each other in a serious situation. If one can detect motor faults in advance, maintenance schedule or parts replacement can be properly arranged to reduce the risk of suddenly shut down in motor operation. This thesis simulates the differences of the characteristics of electric current signals for a three-phase induction motor under normal condition, uneven dispose fault and air-gap eccentric fault using Matlab/Simulink. To verify the feasibility of the models developed in the MATLAB/Simulink environment, the simulated fault signals are compared with the results obtained by other research. Finally, this thesis shows that the air-gap eccentricity degree can rapidly and reliably be diagnosed without using the traditional method to transform the fault signals into the frequency domain by analyzing them with a neural algorithm.

The computational analysis of an eccentric rotor is based on the bondgraph approach where the eccentricity of the rotor is analysed using bondgraph. This approach is used in this experiment to justify the displacements in shaft rotation which is occurring due to eccentricity introduced in the shaft. The computational analysis is necessary because by getting these results, a graph can be plotted which will give an accurate result of the bondgraph approach and it can be seen that by how much the displacement is occurring when the eccentricity is increased. The modelling technique used in this approach introduces two shafts connected through a hub and is provided rotor excitation by connecting it through an external source that rotates it at different angular velocities. The shafts are connected in such a manner that it has displacements in radial axis and the displacement is noted. The bond graph modelling of shaft and spinning hub is done using symbol sonata software bond pad. Simulation of this model has been carried out on Symbols sonata software which uses the fourth order Runge-Kutta method. The variation in the position of centre mass of rotor with change in various parameters such as speed, clearance is observed. The data obtained is used to get plots.

This research studies on behaviour precast wall loaded with a different eccentricity of load using finite element method. Seven (7) models of the wall were developed and analysed using ABAQUS software. All samples are designed with a dimension of 3000 mm height x 3000 mm length and 150 mm thickness by using the main material, which is reinforced concrete. Steel bar reinforcement for all model precast walls was provided with T10-200 in the vertical section and T10-300 in the horizontal section. The concrete grade used for the design of the precast wall in this study is the C35 with a longitudinal steel support of deformed steel reinforcement bars with a nominal yield strength of 460 MPa and for the mild steel is of 250 MPa. The study shows the decrease in deformation shape curve when the eccentricity value increases up to 10 mm. The study also reveals no significant effect on stress distribution regarding the location of stress under different eccentricities of load.

Vibrations play a very important role in rotor systems. In the manufacturing of the rotor system, the imbalance caused by the offset impeller and eccentricity produces unwanted vibrations. Various studies were carried out on unbalanced factors of rotor systems like eccentricity, crack, etc. But the effect of impeller offset due to manufacturing fault is not given much attention. In this study, the change in natural frequencies with respect to disc offset distance was calculated using numerical analysis and experimental analysis for the steel Jeffcott rotor system. Finite element analysis of the offset rotor shaft is carried out in the ANSYS workbench. Experimental modal analysis is carried out using the DAQ system. The accuracy of the model and the solution technique has been observed by comparing experimental results with the numerical simulation results from ANSYS. It is observed that when the disc is shifted from the center, it has a significant effect on transverse and torsional vibrational frequencies. As the disc is shifted towards bearing supports, the stiffness of the system increases, which leads to an increase in vibration frequency.

The subject of eccentrically loaded conforming contacts is approached analytically under the restriction that the eccentricity is small enough to keep the contact closed. This paper advances a numerical method for contact analysis valid at any eccentricity value. An additional loop is added to the classic elastic contact solver to account for load eccentricity. The method predicts contact area and pressure distribution even when the contacting bodies lose contact in some peripheral points. Numerical results of pressure distribution for a circular flat end punch agree well with existing analytical predictions.

Many micromachines use rotating shafts and other moving parts which carry a load and need fluid bearings for support. Most of them operate with air or water as the lubricating fluid. The present study analyzes air microbearing represented as an eccentric cylinder rotating in a stationary housing. The fluid mechanics and operating characteristics of microbearing are different from their larger cousins. The small length-scale may invalidate the continuum approximation in Navier-Stokes equations, and slip flow, rarefaction, compressibility and other unconventional effects may have to be taken into account. Surface effects dominate in small devices due to a high surface-volume ratio. In this study, two-dimensional eccentric-shaft journal microbearings with different eccentricities are simulated by direct simulation Monte Carlo (DSMC) code incorporated with a Volume-CAD software. The diffuse reflection model and Cercignani-Lampis-Lord (CLL) model are applied to model the molecule-surface interaction by considering the accommodation coefficients of shaft wall and housing wall separately. The distribution of mean free path in the flow field indicates that the continuum model may break down and it is necessary to carry our molecular modeling. Calculation results show that at high eccentricity and high accommodation coefficient on the housing wall (ACO) the flow may develop a recirculation region. However, the accommodation coefficient on shaft wall (ACI) does not have any effect on the occurrence of recirculation and the size of recirculation zone. There is antisymmetry of the pressure about a vertical axis, which produces a pressure force on the shaft wall. The influence of ACI to isobars is larger than that of ACO. The shear stress profile on shaft wall is big at low ACI. At the region of short clearance between the shaft wall and housing wall, it is also influenced by the surface condition of housing wall and may even change its direction at low ACO. The pressure profile is reduced in amplitude as the ACI increases, but it is enhanced a little with the increase of ACO. The ACO has great impact on the viscous force in the case of big eccentricity. With the increase of ACI, the viscous force decreases. The pressure force is high at large eccentricity. The influence of ACO to pressure force is insignificant, but the pressure force fall is enormous when ACI increases, especially for large eccentricity. The total force decreases markedly at high eccentricity when ACI increases. The ACO almost has no impact on the total force. The torque increases with ACO, but decreases with ACI. The eccentricity also has great impact on the torque, and the microbeaing may have large torque at high eccentricity. The method developed in this paper would be very useful for designing and evaluating journal microbearing.