This book equips the reader to understand every important aspect of the dynamics of rotating machines. Will the vibration be large? What influences machine stability? How can the vibration be reduced? Which sorts of rotor vibration are the worst? The book develops this understanding initially using extremely simple models for each phenomenon, in which (at most) four equations capture the behavior. More detailed models are then developed based on finite element analysis, to enable the accurate simulation of the relevant phenomena for real machines. Analysis software (in MATLAB) is associated with this book, and novices to rotordynamics can expect to make good predictions of critical speeds and rotating mode shapes within days. The book is structured more as a learning guide than as a reference tome and provides readers with more than 100 worked examples and more than 100 problems and solutions.

/pdf/dynamics-of-rotating-machines-499re2kizd.pdf

Dynamics of rotating machines

Condition monitoring of rotating electrical machinery has received intense research interest for more than 30 years. However, electrical machinery has been considered reliable and the application of fast-acting digital electrical protection has rather reduced the attention operators pay to the equipment. The area based upon current literature and the author's experience is reviewed. There are three restrictions: only on-line techniques for rotating machines are dealt with; specific problems of variable speed drives are not dealt with, except in passing; conventional rather than emerging brushless, reluctance and permanent magnet machines of unusual topology are concentrated upon. The art of condition monitoring is minimalist, to take minimum measurements from a machine necessary to extract a diagnosis, so that a condition can be rapidly inferred, giving a clear indication of incipient failure modes. The current state of the art is reviewed in the following ways: survey developments in condition monitoring of machines, mechanically and electrically, over the last 30 years; put that work in context alongside the known failure mechanisms; review those developments which have proved successful and identify areas of research which require attention in the future to advance the subject.

Review of condition monitoring of rotating electrical machines

Condition monitoring of engineering plant has increased in importance as engineering processes are automated and manpower is reduced. However, electrical machinery receives attention only at infrequent intervals when plant is shut down and the application of protective relays to machines has also reduced operator surveillance. A first edition of Condition Monitoring of Electrical Machines, written by Tavner and Penman, was published in 1987. The economics of industry have now changed, as a result of the privatisation and deregulation of the energy industry, placing emphasis on the importance of reliable operation of plant, throughout the whole life cycle, regardless of first cost. The availability of advanced electronics and software in powerful instrumentation, computers, and digital signal processors (DSP) has simplified our ability to instrument and analyse machinery. As a result condition monitoring is now being applied to a wider range of systems, from fault-tolerant drives of a few hundred watts in the aerospace industry, to machinery of a few hundred megawatts in major capital plant. In this new book the original authors have been joined by Ran, an expert in power electronics and control, and Sedding, an expert in the monitoring of electrical insulation systems. Together the authors have revised and expanded the earlier book, merging their own experience with that of machine analysts to bring it up to date. The book is aimed at professional engineers in the energy, process engineering and manufacturing industries, plus research workers and students.

Condition Monitoring of Rotating Electrical Machines

A work and power (energy) analysis of the golf swing is presented as a method for evaluating the mechanics of the golf swing. Two computer models were used to estimate the energy production, transfers, and conversions within the body and the golf club by employing standard methods of mechanics to calculate work of forces and torques, kinetic energies, strain energies, and power during the golf swing. A detailed model of the golf club determined the energy transfers and conversions within the club during the downswing. A full-body computer model of the golfer determined the internal work produced at the body joints during the downswing. Four diverse amateur subjects were analyzed and compared using these two models. The energy approach yielded new information on swing mechanics, determined the force and torque components that accelerated the club, illustrated which segments of the body produced work, determined the timing of internal work generation, measured swing efficiencies, calculated shaft energy storage and release, and proved that forces and range of motion were equally important in developing club head velocity. A more comprehensive description of the downswing emerged from information derived from an energy based analysis.

/pdf/work-and-power-analysis-of-the-golf-swing-3kakv7b89p.pdf

Work and power analysis of the golf swing

Use of modal representation for the supporting structure in model-based fault identification of large rotating machinery. part 1-theoretical remarks

Turbogenerators in power stations are often placed on foundation structures that are flexible over the running range of the machine and can therefore contribute to its dynamics. Established methods of obtaining structural models for these foundations, such as the finite element method or modal testing, have proved unsuccessful because of complexity or cost. Another method of foundation system identification, using the unbalance excitation applied by the rotor itself during maintenance run-downs, has previously been proposed but has not yet been experimentally verified. In this paper the necessary theory is developed and certain issues critical to the success of the estimation are examined. The method is tested in both simulation and experiment using a two-bearing rotor rig and good fits between model and measurement are obtained. The predictive capacity of the estimated models when the system is excited with a different unbalance is not as good, and it is surmised that this may be due among other ...

/pdf/estimating-turbogenerator-foundation-parameters-2vwlhzr7pv.pdf

Estimating turbogenerator foundation parameters

Estimating a model of the foundation of large machines, such as turbogenerators, is vital for tasks such as fault diagnosis and modal balancing. Unfortunately, it is rarely possible to perform a modal test on the foundations without the rotor present. This paper considers a method to estimate a foundation model using response data from a run–down, using the inherent unbalance of the rotor to excite the foundations. The method requires an accurate model of the rotor and an approximate model of the bearings. Of critical importance is the quality of the model, which may be defined as the ability of the model to predict the response to unbalance excitations that are different from that present for the identification. It is shown in this paper that correct model selection and regularization are vital to produce a foundation model that meets this predictability criterion. The method is validated using simulated data and also experimental data from a test rig with a 4 m long rotor with four fluid film bearings.

http://michael.friswell.com/PDF_Files/J61.pdf

Estimating turbogenerator foundation parameters: model selection and regularization

Computing critical speeds for rotating machines with speed dependent bearing properties

This paper aims to improve a finite element model of a golf club by using measured experimental natural frequencies and mode shapes. Only the low frequency dynamics of the club are considered, making the improved model suitable for studies of the dynamics of the swing. The shaft was modelled using beam elements and the head was represented as a rigid body. The natural frequencies of the club were measured and compared to those predicted from the analytical model. The flexibility properties of the shaft were modelled using the generic parameter approach. These parameters and the inertia properties of the head were estimated from the measured data to produce an improved analytical model. Subset selection was employed to determine those characteristics of the club that were poorly modelled. The inertia about the shaft axis and the shaft flexibility, particularly the torsional stiffness, have been identified as the most likely to be in error.

/pdf/dynamic-models-of-golf-clubs-35qwu4i4hy.pdf

Dynamic models of golf clubs

This paper compares the results of the dynamic modelling of typical golf clubs and measurements made on the same clubs. The shaft was modelled using beam elements and the head was represented as a rigid body. The natural frequencies of the club were measured and compared to those predicted from the analytical model. The stiffness of the shaft and the inertia properties of the head were estimated from the measured data to produce an improved analytical model.

Updating finite element models of golf clubs

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