Roller gear cam (RGC) mechanisms are widely used in modern industries. While operated at high speeds, the indexing precision of these devices will be influenced by their dynamic characteristics. In this study, the Bond Graph Method is employed to construct a mathematical model to simulate the dynamic responses of RGC mechanisms. Meanwhile, associated experiments will be made to verify the effectiveness of this model. The influences of torque compensation mechanisms and different cam motion curves affecting the dynamic response of a RGC mechanism are observed. And the results show that the torque compensation mechanism is effective to the dynamic performance, and high-speed stability of a RGC mechanism. Besides, the simulated results also indicate that the kinematic properties of cam motion curves have certain influences on the residual vibrations of the system.

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Measured and predicted static and dynamic characteristics are provided for a four-pad, rocker-pivot, tilting-pad journal bearing in the load-on-pad and load-between-pad orientations. The bearing has the following characteristics: 4 pads, .57 pad pivot offset, 0.6 L/D ratio, 60.33 mm (2.375in) pad axial length, 0.08255 mm (0.00325 in) radial clearance in the load-on-pad orientation, and 0.1189 mm (0.00468 in) radial clearance in the load-between-pad orientation. Tests were conducted on a floating test bearing design with unit loads ranging from 0 to 2903 kPa (421.1 psi) and speeds from 6.8 to 13.2 krpm. For all rotor speeds, hot-clearance measurements were taken to show the reduction in bearing clearance due to thermal expansion of the shaft and pads during testing. As the testing conditions get hotter, the rotor, pads, and bearing expand, decreasing radial bearing clearance. Hot-clearance measurements showed a 16-25% decrease in clearance compared to a clearance measurement at room temperature. For all test conditions, dynamic tests were performed over a range of excitation frequencies to obtain complex dynamic stiffness coefficients as a function of frequency. The direct real dynamic stiffness coefficients were then fitted with a quadratic function with respect to frequency. From the curve fit, the frequency dependence was captured by including a virtual-mass matrix [M] to produce a frequency independent [K][C][M] model. The direct dynamic stiffness coefficients for the load-on-pad orientation showed significant orthotropy, while the load-between-pad did not. The load-between-pad showed slight orthotropy as load increased. Experimental cross-coupled stiffness coefficients were measured in both load orientations, but were of the same sign and significantly less than direct stiffness coefficients. In both orientations the imaginary part of the measured dynamic stiffness increased linearly with increasing frequency, allowing for frequency independent direct damping coefficients. Rotordynamic coefficients presented were compared to predictions from two different Reynolds-based models. Both models showed the importance of taking into account pivot flexibility and different pad geometries (due to the reduction in bearing clearance during testing) in predicting rotordynamic coefficients. If either of these two inputs were incorrect, then predictions for the bearings impedance coefficients were very inaccurate. The main difference between prediction codes is that one of the codes incorporates pad flexibility in predicting the impedance coefficients for a tilting-pad journal bearing. To look at the effects that pad flexibility has on predicting the impedance coefficients, a series of predictions were created by changing the magnitude of the pad's bending stiffness. Increasing the bending stiffness used in predictions by a factor of 10 typically caused a 3-11% increase in predicted Kxx and Kyy, and a 10-24% increase in predicted Cxx and Cyy. In all cases, increasing the calculated bending stiffness from ten to a hundred times the calculated value caused slight if any change in Kxx, Kyy, Cxx, and Cyy. For a flexible pad an increase in bending stiffness can have a large effect on predictions; however, for a more rigid pad an increase in pad bending stiffness will have a much lesser effect. Results showed that the pad's structural bending stiffness can be an important factor in predicting impedance coefficients. Even though the pads tested in this thesis are extremely stiff, changes are still seen in predictions when the magnitude of the pad?s bending stiffness is increased, especially in Cxx, and Cyy. The code without pad flexibility predicted Kxx and Kyy much more accurately than the code with pad flexibility. The code with pad flexibility predicts Cxx more accurately, while the code without pad flexibility predicted Cyy more accurately. Regardless of prediction Code used, the Kxx and Kyy were over-predicted at low loads, but predicted more accurately as load increased. Cxx, and Cyy were modeled very well in the load-on-pad orientation, while slightly overpredicted in the load-between-pad orientation. For solid pads, like the ones tested here, both codes do a decent job at predicting impedance coefficients

The main components of the vibration-based microgenerator incorporate vibratile structure, magnetic thin film, and coils. In this thesis work, bulk-micromachining technology and laser-micromachining technology were used to fabricate the vibratile structure of the microgenerator. And this is the beginning of the development of the microgenerator. Bulk-micromachining technology was widely used in micro-electromechanical system (MEMS). The most advantage of the technology is that it can be integrated with IC process in the future. And the roughness of the wafer is the key point of the etching process. In addition, 355nm UV Nd:YAG laser was also used to fabricate the vibratile structure. The period of fabricating prototype can be shortened by laser-micromachining. In laser-micromachining system, the dual-prism was used to change the direction of the laser beam by adjusting the initial phase of one of the prisms. When the laser beam moves relatively to workstation, the cutting process can be proceeded. By this system, the cutting linewidth is controllable. This technology has be used to fabricate the microstructure successfully, and the aspect ratio is up to 10, and the feature size is 50µm. Circular spiral spring structure was fabricated successfully, and it is to be the vibratile structure of the microgenerator. Finite element software ANSYS was used to simulate the dynamic characterization of the vibratile structure and the vibration testing experiment was carried out. The result shows that the experimental resonant frequency is very close to the simulative resonant frequency. So this vibratile structure can be used in microgenerator.

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The analysis of the feature and application of linear induction motors at work have been performed; mathematical models of linear motors have been studied; mathematical description of induction machine have been presented; coordinate transform have been studied; dynamic equations in moving and move-less systems of axes of linear induction motor have been presented; the analysis of the classification of induction drives control modes have been performed. Four models of the frequency-regulated electric drives with linear induction motors have been studied: when the motor is supplied from variable frequency mains supply, when the motor is supplied from frequency converter, when frequency is changed by program, when frequency is changed in close-loop by vector control system. The characteristics of those models have been compared and performed. The received results are summarized in the conclusions.

Abrasive waterjet (AWJ) cutting is one of the most recently developed nontraditional manufacturing technologies. It has been increasingly used in industry owing to its various distinct advantages over the other cutting technologies. However, many aspects of this technology require to be fully understood in order to increase its capability and cutting performance as well as to optimize the cutting process. This thesis contains an extensive literature review on the investigations of the various aspects in AWJ machining. It shows that while considerable work has been carried out, very little reported research has been found on the AWJ contouring process although it is a common AWJ cutting application. Because of the very nature of the AWJ cutting process, the changing nozzle traverse direction involved in AWJ contouring results in kerf geometrical or shape errors. A thorough understanding of the AWJ contouring process is essential for the reduction or elimination of these shape errors. It also shows that a lack of understanding of the AWJ hydrodynamic characteristics has limited the development of cutting performance models that are required for process control and optimization. Accordingly, a detailed experimental investigation is presented in this thesis to study the various cutting performance measures in AWJ contouring of an 87% alumina ceramic over a wide range of process parameters. For a comparison purpose, the study also considers AWJ straight-slit cutting. The effects of process parameters on the major cutting performance measures in AWJ contouring have been comprehensively discussed and plausible trends are amply analysed. It finds that the taper angles on the two kerf walls are in different magnitudes in AWJ contouring. The kerf taper on the outer kerf wall increases with the arc radius (or profile curvature), while that on the inner kerf wall decreases. Moreover, the depth of cut increases with an increase in arc radius and approaches the maximum in straight cutting for a given combination of parameters. The other process variables affect the AWJ contouring process in a way similar to that in straight cutting. The analysis has provided a guideline for the selection of process parameters in the AWJ contouring of alumina ceramics. In order to predict the cutting performance in process planning and ultimately optimize the cutting process, mathematical models for the major cutting performance measures in both straight-slit cutting and contouring are developed using a dimensional analysis technique. The models are then verified by assessing both qualitatively and quantitatively the model predictions with respect to the corresponding experimental data. It shows that the models can adequately predict the cutting performance measures and form the essential basis for developing strategies for selecting the optimum process parameters in AWJ cutting. To achieve an in-depth understanding of the jet dynamic characteristics such as the velocity and pressure distributions inside a jet, a Computational Fluid Dynamics (CFD) simulation is carried out using a Fluent6 flow solver and the simulation results are validated by an experimental investigation. The water and particle velocities in the jet are obtained under different input and boundary conditions to provide an insight into the jet characteristics and a good understanding of the kerf formation process in AWJ cutting. Various plausible trends and characteristics of the water and particle velocities are analysed and discussed, which provides the essential knowledge for optimizing the jet performance through optimizing the jetting and abrasive parameters. Mathematical models for the water and particle velocity distributions in an AWJ are finally developed and verified by comparing the predicted jet characteristics with the corresponding CFD simulation data. It shows that the jet characteristics models can yield good predictions for both water and particle velocity distributions in an AWJ. The successful development of these jet dynamic characteristics models is an essential step towards developing more comprehensive mathematical cutting performance models for AWJ cutting and eventually developing the optimization strategies for the effective and efficient use of this advanced manufacturing technology.

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Baigiamajame magistro darbe nagrinėjama iešmo elektros pavara su tiesiaeigiu asinchroniniu cilindriniu varikliu. Programiniu paketu ,,Matlab“ yra sudaryti pavaros matematiniai modeliai α, β koordinačių sistemoje. Uždaviniai – tiesiaeigės iešmo elektros pavaros kompiuterinio modelio sudarymas, tyrimas ir dinaminių charakteristikų imitavimas. Literatūros analizės dalyje išnagrinėtos tiesiaeigės elektros pavaros, jų taikymo sritys bei valdymo būdai. Magistro darbo teorinėje dalyje pateikiamos tiesiaeigių elektros pavarų skaičiavimo ir valdymo metodikų analizės. Tiriamoji dalis apima iešmo elektros pavaros su tiesiaeigiu cilindriniu asinchroniniu varikliu matematinių modelių sudarymą ir dinaminių charakteristikų tyrimą programiniu paketu ,,Matlab“. Matematiniai modeliai yra sudaromi pavarai veikiant skirtingais darbo režimais (pavara perjungiama neapkrauta, pavara perjungiama apkrovus nominalia apkrova ir iešmą perjungiant pabaigoje ir pradžioje trukdant papildomai pasipriešinimo jėgai) ir tyrimo rezultatai pateikiami grafiškai. Gauti rezultatai yra palyginami ir apibendrinami. Išnagrinėjus teorinius tiesiaeigės iešmo elektros pavaros su asinchroniniu cilindriniu varikliu darbo režimų aspektus, pateikiamos išvados ir pasiūlymai. Tyrimo rezultatai gali būti panaudoti iešmo elektros pavaros su tiesiaeigiu asinchroniniu varikliu racionaliam ir optimaliam realizavimui geležinkelio transporto automatinio valdymo sistemose. Darbą sudaro 9 dalys: santrumpos ir simboliai, įvadas... [toliau žr. visą tekstą] / The final Bachelor thesis analyses point electric drive with cylinder-type linear asynchronous motor. Software package ,,Matlab“ was used to prepare mathematical models of the drive in α, β coordinate system. Objectives: preparing and analyzing a computer model of linear point electric drive, simulation of dynamic characteristics. The analysis of literary sources deals with linear electric drives, their application areas and methods of control. Theoretical part of the Master thesis presents analyses of calculation and control methods of linear electric drives. The analytical part of the thesis includes mathematical models of point electric drive with cylinder-type linear asynchronous motor and the analysis of dynamic characteristics using software package ,,Matlab“. Mathematical models were prepared when the drive operated in different modes (the drive switched without load, the drive switched with nominal load, the switch connected at the end or beginning, thereby blocking additional resistance force). Research results were presented in a graphical form. Obtained results were compared and summarized. Following the analysis of the theoretical aspects of operating modes of linear point electric drive with cylinder-type asynchronous motor, conclusions and recommendations were presented. Research results can be used for rational and optimal realization of point electric drive with linear asynchronous motor in automatic railway control systems. The thesis consists of nine parts:... [to full text]