Health Monitoring of Cracked Rotor Systems Using External Excitation Techniques

Cracked rotors present a significant safety and loss hazard in nearly every application of modern turbomachinery. This thesis focuses on the health monitoring, modeling, and analysis of machines with transverse breathing cracks, which open and close due to the self-weight of the rotor. After considering the modeling of cracked rotors, the thesis investigates an active structural health monitoring approach, focusing on the application of an active magnetic actuator to apply a specially designed external force excitation to the rotating shaft. Extensive experimental data has been collected and analyzed utilizing advanced diagnostic techniques. The presented results demonstrate that the use of a magnetic force actuator to apply external excitation has potential in the diagnostics of cracked rotors. The observed unique crack signatures demonstrate the ability of the method for early diagnosis of transverse rotor crack

Health Monitoring of Cracked Rotor Systems Using External Excitation Techniques

Cracked rotors present a significant safety and loss hazard in nearly every application of modern turbomachinery. This thesis focuses on the health monitoring, modeling, and analysis of machines with transverse breathing cracks, which open and close due to the self-weight of the rotor. After considering the modeling of cracked rotors, the thesis investigates an active structural health monitoring approach, focusing on the application of an active magnetic actuator to apply a specially designed external force excitation to the rotating shaft. Extensive experimental data has been collected and analyzed utilizing advanced diagnostic techniques. The presented results demonstrate that the use of a magnetic force actuator to apply external excitation has potential in the diagnostics of cracked rotors. The observed unique crack signatures demonstrate the ability of the method for early diagnosis of transverse rotor crack

Second International Symposium on Magnetic Suspension Technology, part 2

In order to examine the state of technology of all areas of magnetic suspension and to review related recent developments in sensors and controls approaches, superconducting magnet technology, and design/implementation practices, the 2nd International Symposium on Magnetic Suspension Technology was held at the Westin Hotel in Seattle, WA, on 11-13 Aug. 1993. The symposium included 18 technical sessions in which 44 papers were presented. The technical sessions covered the areas of bearings, bearing modelling, controls, vibration isolation, micromachines, superconductivity, wind tunnel magnetic suspension systems, magnetically levitated trains (MAGLEV), rotating machinery and energy storage, and applications. A list of attendees appears at the end of the document

Design and Implementation of Modern Controls for Drive and Suspension of a High Speed Double Conical Bearingless Motor on a Real-Time System

In this work, modern control approaches for drive and suspension of a high speed double conical bearingless motor are designed. Firstly, the air gap flux density and the forces acting on the rotor are analytically calculated. Subsequently, an elaborate model of the magnetically levitated rotor is developed, which considers the non-collocation of position sensors and levitation windings as well as the presence of angular motion. Three different control approaches are designed and simulated. The first approach comprises a state controller augmented with integral action, with which the closed loop dynamics are freely defined after pole placement. The other two approaches concern Linear Quadratic Gaussian and Model Predictive control. The pole placement control approach is tested successfully on the test bench with the real motor. Sinusoidal disturbance forces, with the rotational frequency, can cause large rotor orbits and may drive the inverters to their limits. For this reason, two synchronous filtering control strategies are developed. Using Imbalance Force Compensation, the rotor can be driven with low orbits at relatively low speed and using Imbalance Force Rejection, the rotor can be driven with low levitation currents at high speed. The control performance is evaluated by measurements and the measured frequency response of the closed loop system is presented

Assuring safety in high-speed magnetically levitated (maglev) systems : the need for a system safety approach

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2008.Includes bibliographical references (p. 141-145).Magnetic levitation is a railway technology that enables vehicles to be magnetically suspended above their tracks. Although this technology is still under development, magnetically levitated (maglev) systems have great potential to introduce significant changes in today's transportation networks. This thesis proposes an approach to assuring safety in high-speed maglev systems. It examines characteristic features of the systems, and analyzes the Japanese commuter railway accident in 2005, using Systems Theory Accident Modeling and Processes (STAMP) and System Dynamics models. The characteristic features reveal that the likelihood and potential severity of accidents in maglev systems are higher than those in conventional railway systems because of their high speed, levitation technology, software intensiveness, and other factors. A primary lesson learned from the accident is the importance of risk/hazard analysis that can qualitatively focus on the severity of accidents and human factors. These findings are put together in the form of requirements of risk/hazard analysis and organizational structures. This thesis demonstrates that these requirements, which are not entirely consistent with current actual practices based on international railway standards, conform well to the fundamentals of System Safety, which is an organized and established method to assure safety in complex systems.by Shuichiro Daniel Ota.S.M

Fourth International Symposium on Magnetic Suspension Technology

In order to examine the state of technology of all areas of magnetic suspension and to review recent developments in sensors, controls, superconducting magnet technology, and design/implementation practices, the Fourth International Symposium on Magnetic Suspension Technology was held at The Nagaragawa Convention Center in Gifu, Japan, on October 30 - November 1, 1997. The symposium included 13 sessions in which a total of 35 papers were presented. The technical sessions covered the areas of maglev, controls, high critical temperature (T(sub c)) superconductivity, bearings, magnetic suspension and balance systems (MSBS), levitation, modeling, and applications. A list of attendees is included in the document

Development of a Pediatric cardiac assist Maglev pump for use with a universal driver system.

Heart failure (HF) remains the leading cause of death, affecting 26 million adults worldwide and 6.5 million adults in the United States. Pediatric HF patients have been a historically underserved population with few options for mechanical circulatory support (MCS) therapy, a leading treatment as an alternative to heart transplantation. To address this clinical need, the Inspired Universal MagLev System is being developed; a low cost, universal magnetically levitated extracorporeal MCS system with interchangeable single-use pumps that will ultimately provide adult and pediatric patients ventricular and respiratory assist therapies. The Inspired Pediatric VAD is the first single-use pump application for this MCS system and is specifically designed for pediatric circulatory support. This dissertation describes the development efforts to design and evaluate iterative impeller and pump housings for the Inspired Pediatric VAD. Requirements for the Inspired Pediatric VAD design include the need to generate the appropriate hemodynamic parameters (pressures and flows) for pediatric patients, and miniaturization of the pump and impeller to accommodate the pediatric population. Traditional pump theory and design methods were applied to aid in the unique design of the VAD impeller and pump housing, resulting in multiple design iterations. Two impeller and pump designs (V1, V2) were virtually constructed using computer-aided design (CAD) software. Three-dimensional flow and pressure features were analyzed using computational fluid dynamics (CFD) analysis. Simulated pump designs (V1, V2) were operated at 15% higher rotational speeds (~5000 rpm) than initially estimated (4255 rpm) to achieve the desired operational point (3.5 L/min flow at 150 mmHg). V2 design outperformed V1 by generating up to 30% higher pressures at all simulated rotational speeds and with 5% lower priming volume. Simulated hydrodynamic performance (flow, pressure and hydraulic efficiency) of VAD V2 compared favorably to current commercially available MCS devices. A prototype of the Inspired Pediatric VAD V2 was fabricated, the magnitude and range of hydraulic torque and forces of the impeller were quantified, and the hydrodynamic performance benchmarked. A static mock flow loop model containing a heated blood analogue solution was created to test the pump over a range of rotational speeds (500 - 6000 RPM), flow rates (0 - 3.5 L/min), and pressures (0 to ~420 mmHg). The device was initially powered by a shaft driven DC motor, which was used to calculate the fluid torque acting on the impeller. Additional CFD simulations of VAD V2 were compared against the empirical bench-top data at select rotational speed and flow rate conditions. Empirically, the pediatric VAD produced flows as high as 4.3 L/min against a pressure of 127 mmHg at 6000 RPM. Based on the performance of the first two VAD design iterations, a final design iteration, VAD V3, was achieved. Hydrodynamic performance of VAD V3 was numerically assessed using CFD simulations. The results indicated no change in flow and pressure head performance compared to the previous device design (V2). Shear stress and flow residence time volumetric distributions were generated over a range of pump rotational speeds and flow rates. At the lowest pump operating point (3000 RPM, 0.50 L/min, 75 mmHg), 79% of the pump volume was in the shear stress range of 0 – 10 Pa with \u3c 1% of the volume in the critical range of 150 – 1000 Pa associated with potential for increased risk of clinically-significant blood damage. At higher speed and flow (5000 RPM, 3.50 L/min, 176 mmHg), 65% of the volume resided in the 0 – 10 Pa range compared to 2.3% at 150 – 1000 Pa. The initial results from the computational characterization of the Inspired Pediatric VAD V3 were encouraging, and based on the overall research performed to date, future work will include pre-clinical testing of VAD V3 in static and dynamic mock flow loop and acute large animal model studies to further assess device function, hydrodynamic performance, hemodynamic response, and hemocompatibility

SIRM 2017

This volume contains selected papers presented at the 12th International Conference on vibrations in rotating machines, SIRM, which took place February 15-17, 2017 at the campus of the Graz University of Technology. By all meaningful measures, SIRM was a great success, attracting about 120 participants (ranging from senior colleagues to graduate students) from 14 countries. Latest trends in theoretical research, development, design and machine maintenance have been discussed between machine manufacturers, machine operators and scientific representatives in the field of rotor dynamics. SIRM 2017 included thematic sessions on the following topics: Rotordynamics, Stability, Friction, Monitoring, Electrical Machines, Torsional Vibrations, Blade Vibrations, Balancing, Parametric Excitation, and Bearings. The papers struck an admirable balance between theory, analysis, computation and experiment, thus contributing a richly diverse set of perspectives and methods to the audience of the conference

12th International Conference on Vibrations in Rotating Machinery

Since 1976, the Vibrations in Rotating Machinery conferences have successfully brought industry and academia together to advance state-of-the-art research in dynamics of rotating machinery. 12th International Conference on Vibrations in Rotating Machinery contains contributions presented at the 12th edition of the conference, from industrial and academic experts from different countries. The book discusses the challenges in rotor-dynamics, rub, whirl, instability and more. The topics addressed include: - Active, smart vibration control - Rotor balancing, dynamics, and smart rotors - Bearings and seals - Noise vibration and harshness - Active and passive damping - Applications: wind turbines, steam turbines, gas turbines, compressors - Joints and couplings - Challenging performance boundaries of rotating machines - High power density machines - Electrical machines for aerospace - Management of extreme events - Active machines - Electric supercharging - Blades and bladed assemblies (forced response, flutter, mistuning) - Fault detection and condition monitoring - Rub, whirl and instability - Torsional vibration Providing the latest research and useful guidance, 12th International Conference on Vibrations in Rotating Machinery aims at those from industry or academia that are involved in transport, power, process, medical engineering, manufacturing or construction