bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analytical and Experimental Simulation of Loose Pedestal Dynamic Effects on a Rotating Machine Vibrational Response
Authors: Goldman Pavel , Muszynska Agnes 
Published: April 2021

Abstract
This report presents experimental, analytical, and numerical results describing vibrational phenomena in a rotating machine with one loose pedestal. The loose-pedestal machine rotor vibrations represent unbalance-related excited vibrations of synchronous and fractional subsynchronous regimes. In this study the loose-pedestal machine is first simulated by a simple vibrating beam excited by a shaker mounted on it. The shaker simulates an unbalanced machine rotor. The beam occasionally enters in contact with the foundation. The excited vibrations are modified by impacting occurrences, and by periodic changes in system stiffness. A new model of the impact has been developed. The results of analytical and experimental studies stand in a good agreement. They illustrate the existence of the synchronous regime and several subsynchronous fractional regimes in various excitation frequency ranges. The analysis adequately predicts the occurrence of these regimes and determines the physical parameters affecting them. The analytical and experimental results are then compared with the responses of experimental rotor rig with one bearing pedestal looseness. They show the same qualitative pattern.
Active Vibration Control of Flexible Rotor Using H∞ Control Theory
Authors: Nonami K. , Wang J. W. , Sampei M. , Mita T. 
Published: April 2021

Abstract
This paper investigates about H∞ control for a flexible rotor model and suppression of spillover phenomena caused by modelling of reduced order. A H∞ control system is designed such that unmodelled vibration modes in a high frequency range are not excited, i.e., a spillover phenomena are not caused to happen. Simulation results are presented to demonstrate the control effects. Since the H∞ control problem in this paper reduces to a special case in the standard H∞ control problem, a new method is employed to solve it.
Accurate Free Vibration Analysis for Rotating Shaft
Authors: Yang Bo Suk , Pilkey Walter D. 
Published: April 2021

Abstract
This paper presents an approach for the derivation of dynamic mass, gyroscopic and stiffness matrices for rotor dynamics analyses. The axial, torsional and bending dynamic stiffness matrices are deduced from transfer matrices, and, in turn, the frequency-dependent element matrices are derived. The relationships between the dynamic stiffness matrix and the frequency-dependent element matrices are defined. Numerical examples show that this method gives more accurate results than those obtained using the conventional static shape function based element matrices.
The Rocketdyne Multifunction Tester: Operation of a Radial Magnetic Bearing As an Excitation Source
Authors: Hawkins L. A. , Murphy B. T. , Lang K. W. 
Published: April 2021

Abstract
The operation of the magnetic bearing used as an excitation source in the Rocketdyne Multifunction Tester is described. The tester began operation during the summer of 1990. The magnetic bearing can be used in two control modes: 1) open loop mode, in which the magnetic bearing operates as a force actuator, and 2) closed loop mode, in which the magnetic bearing provides shaft support. Either control mode can be used to excite the shaft; however, response of the shaft in the two control modes is different due to the alteration of the eigenvalues by closed loop mode operation. A rotordynamic model is developed to predict the frequency response of the tester due to excitation in either control mode. Closed loop mode excitation is shown to be similar to the excitation produced by a rotating eccentricity in a conventional bearing. Predicted frequency response of the tester in the two control modes is compared, and the maximum response is shown to be the same for the two control modes when synchronous unbalance loading is not considered. The analysis shows that the response of this tester is adequate for the extraction of rotordynamic stiffness, damping, and inertia coefficients over a wide range of test article stiffnesses.
Estimation of Response and Loss Factor of Damped Sandwich Beam
Authors: Markuš Š. , Nánási T. 
Published: April 2021

Abstract
Classical governing equations of a three-layered sandwich beam are generalized with the aim to avoid the necessity of identical arrangement of both face layers at the end of the beam. In this way more shear deformations in the core are allowed for. This may significantly contribute to the increased dissipation of vibratory energy. Estimation of the response of the damped sandwich beam and the loss factor are based on truncated integral modal transformation in which the base functions are the modal data from the associated undamped system. Simple formula expressing the modal loss factor in terms of the portion of strain energy due to shear deformations in the core is developed. Presented approach is in fact a reinterpretation of the concept of damped normal modes in such a way that numerical computations are to be carried out only in the real domain while the previous formulation required numerical treatment in the complex domain.
Characteristic Study of Torsional Vibration on a Full Size Turbine-Generator Unit
Authors: Xiuzhu Huang , Xueyan Zhang , Daixia Sun , Qing Gong 
Published: April 2021

Abstract
Taking a 200MW turbine-generator unit and its connected transsmision network as a study object, torsional vibration characteristics of the shaft system caused by faulty synchronization, different disturbances in the network and switch operation were analysed and calculated. The effect of intensive excitation and “fast valve closing” on the torsional response is also discussed. It is concluded that large mechanical torque of shaft system would be encountered if there is a 3-phase fault in the network, and the shaft torque would be reduced to a certain extent by giving the “fast valve closing” if the network experience a fault.
Vibrations of Spinning Rings With Radial and Circumferential Displacement Constraints
Authors: Huang Shyh-Chin , Su Chen-Kai 
Published: April 2021

Abstract
The frequencies and mode shapes of rolling rings with radial and circumferential displacement constraints are investigated. The displacement constraints practically come from the point contact, e.g., rolling tire on the road, or other applications. The proposed approach to analysis is calculating the natural frequencies and modes of a non-contacted spinning ring, then employing the receptance method for displacement constraints. The frequency equation for the constrained system is hence obtained, and it can be solved numerically or graphically. The receptance matrix developed for the spinning ring is surprisingly found not symmetric as usual. Moreover, the cross receptances are discovered to form complex conjugate pairs. That is a feature that has never been described in literature. The results show that the natural frequencies for the spinning ring in contact, as expected, higher than those for the non-contacted ring. The variance of frequencies to rotational speeds are then illustrated. The analytic forms of mode shapes are also derived and sketched. The traveling modes are then shown for cases.
Dynamics of Flexible Beams and Plates Under Large Overall Motions
Authors: Boutaghou Z.-E. , Erdman A. G. , Stolarski H. K. 
Published: April 2021

Abstract
The dynamic response of flexible beams, plates, and solids undergoing arbitrary spatial motions are systematically derived via a unified approach. This formulation is capable of incorporating arbitrary representation of the kinematics of deformation, phenomenon of dynamic stiffening, and complete nonlinear interaction between elastic- and rigid-body dynamics encountered in constrained multi-body systems. It is shown that the present theory captures the phenomenon of dynamic stiffening due to the transfer of the axial and membrane forces to the bending equations of beams and plates, respectively. Examples are presented to illustrate the proposed formulations.
Design of Damping Treatments for Plates
Authors: Stevens K. K. 
Published: April 2021

Abstract
A series of aids and rules for the design or analysis of complete or partial free-layer viscoelastic damping treatments for plates and panels are presented. Attention is restricted to damping treatments whose flexural rigidity is much less than that of the underlying structure — a condition satisfied by many damping treatments encountered in practice. The underlying theory is described. Use of the aids is illustrated via examples. Results presented are for edge-fixed and simply-supported rectangular plates. Results for other cases can be generated using the procedures described.
Effect of Shear Deformation on Free Flexural Vibration of Clamped Rectangular Plates
Authors: Cleghorn W. L. , Yu S. D. 
Published: April 2021

Abstract
Reissner’s theory on shear-deformable plates is applied to analyze free flexural vibration of clamped rectangular plates. Accurate analytical solutions are obtained using the method of supeiposition. The first six eigenvalues with four digits of accuracy are presented for plates with three thickness ratios and six plate aspect ratios.
Dynamic Characteristics of Scraper-Discharge Material Centrifuge
Authors: Weirong Hong , Baotang Zhou , Shizheng Hu , Kamala V. , Sankar T. S. 
Published: April 2021

Abstract
This paper deals with the dynamic characteristics of scraper-discharge material centrifuge. The bowl center of gravity and the critical speed of rotor system have been calculated. Both One- and Two-plane field dynamic balancing methods suitable for this type of centrifuge are nalyzing. The design of isolator used with this type of centrifuge is also discussed since severe vibrations have developed during the operation. In traditional isolator design, transmissibility is obtained by extracting root of the differential equation for the multi-degree freedom system which is an elaborate method. In this paper, the transmissibility is obtained by the impedeance analysis method. The calculations are simple and agree well with the experimental results.
Displacement Time Histories by Direct Numerical Integration of Acceleration Data
Authors: Wang M. L. , Subia S. R. 
Published: April 2021

Abstract
Acceleration measurements often provide the engineer with a means by which to determine the forces within dynamic structural systems. However for certain problems, information about the structural motion, the displacement-time history, may also be of interest. One such application deals with the evaluation of stiffness in reinforced concrete structures during seismic events. Scaled model tests of these events suggest that the stiffness of these structures often degrades drastically. The displacement response of these seismic events are required both for the development and evaluation of postulated structural stiffness models. This paper discusses the processing of acceleration data from scaled model tests to obtain displacement-time histories for low aspect shear walls subject to simulated seismic loadings. Displacement histories obtained in the time domain are compared with those produced using a frequency domain system identification analysis.
Random Response of a Sluice Gate Support
Authors: Feng W. Q. , Huang T. C. , Liu W. J. , Dong G. X. 
Published: April 2021

Abstract
By the use of the extended finite element method the analysis of the random response of a linear structure to a continuous excitation field, random in time and space, is presented in this paper. The extended finite element method includes the formulation for obtaining the equivalent node force power spectrum. The corresponding computer program has been produced. A random response analysis of a sluice gate support shows satisfactory agreement with the experiment results.
The Effect of an Electromagnetic Damper on Vibrations in Rotating Machinery
Authors: Kasarda M. E. F. , Allaire P. E. , Humphris R. R. , Gunter E. J. 
Published: April 2021

Abstract
Compressors, turbines and other rotating machines often have long thin shafts which may cause vibration problems. An electromagnetic damper placed on the rotor of a machine represents one method of controlling high levels of vibrations. This paper discusses experimental results of an electromagnetic damper placed on a small three mass test rotor. Experimental data was taken for cases with the damper at three different locations on the highly unbalanced rotor to study the effectiveness of the damper in controlling vibrations at the first and second rotor bending modes and at a pedestal response mode. Reductions of vibrations up to 88%, 40%, and 19% were achieved for the first critical speed, second critical speed, and pedestal response mode, respectively. Values of magnetic damper stiffness and damping used to obtain these reductions were only a small fraction of the fluid film bearing damping and stiffness properties.
Modification of Stiffness for Shifting Natural Frequencies of Damped Mechanical Systems
Authors: Yee Eric K. L. , Tsuei Y. G. 
Published: April 2021

Abstract
A method for shifting the natural frequency of a damped mechanical system to a desired value is discussed. The solution is derived from the force response equation of the original system. The final equation contains only the degrees of freedom connected to the modifying parameter. Iterations are required but the solution converges rapidly. Modal coupling effects and sensitivity for shifting a frequency are also derived. Modification of stiffness is used as an example for shifting the natural frequency. Numerical results indicate that the method is effective for system dynamics modification.
Sliding Mode Control of a Rigid Rotor via Magnetic Bearings
Authors: Sinha A. , Mease K. L. , Wang K. W. 
Published: April 2021

Abstract
This paper deals with the sliding mode control of a rigid rotor supported by radial magnetic bearings. First, the control law is developed to be robust to external forces caused by the rotor unbalance and transient disturbances. This control law is then discretized for its implementation on a digital computer. Three methods are presented to determine the required coil current for each magnet. Next, an analytical technique has been developed to calculate the steady state amplitudes of the digital closed-loop system. Lastly, results from this analytical technique and numerical simulations are presented for the rotor operating at 30,000 rpm.
Dual Active and Passive Control of Large Flexible Structures
Authors: Pan T. S. , Rao S. S. , Venkayya V. B. 
Published: April 2021

Abstract
A unified passive damping design algorithm, using active control design techniques and least squares method, is developed to improve the stability and performance of closed-loop controlled structures. To achieve the stringent requirements of large flexible structures (LFS), dual active/passive control using interacting substructure decentralized control and unified passive damping design method is introduced. Physical coordinates are used in modeling; since no modal data is used, no modal errors are involved in the modeling process. Examples are presented to illustrate the design procedures and their effectiveness.
Experimental Determination of Dynamic Characteristics of a Full Size Gas Turbine Tilting-Pad Journal Bearing by an Impact Test Method
Authors: Chan S. H. , White M. F. 
Published: April 2021

Abstract
Measurements have been taken on an experimental rotor-bearing test rig which consists of a full size gas turbine shaft supported by two five-pad tilting-pad journal bearings. The impact test method was applied by exciting one end of the shaft in-situ by means of a hammer blow. Impact forces and response displacements were collected and analysed with suitable corrections for runout effect. Averaged frequency response spectra thus obtained were used in a parameter estimation procedure to calculate the dynamic coefficients of the tested tilting-pad journal bearing. An analytical single degree-of-freedom model was employed and one of the input parameters in the mechanical model, the effective mass, was found to significantly influence the estimated results. The measured stiffness and damping coefficients are compared with results predicted by a bearing design program. Possible sources of discrepancies between experimental and theoretical results are discussed.
Investigation of Avionics Module Connector Wear
Authors: Winslow David T. 
Published: April 2021

Abstract
The methodology for reducing excessive wear on the connector of a module in an avionics system in vibration is presented in this paper. Because of space limitations and time constraints, we designed special test fixtures and techniques to monitor the module system. Traditional differential accelerometers were unsuccessful in determining the relative displacement between the male and female halves of the connector. As an alternative, we implemented an optical probe. The probe measures distance directly through the amount of light reflected off a surface. The data obtained using the optical probe enabled a determination that the maximum allowable displacement to reduce the connector wear was 0.0003 inch rms. Based on these results, we designed and tested hardware modifications, which resulted in the avionics unit surviving the vibration environment.
Case Study Approach for Information-Integration of Material Handling
Authors: Chadha Bipin , Fulton R. E. , Calhoun J. C. 
Published: April 2021

Abstract
Information-Integration is vital for keeping manufacturing operations competitive. A case study approach has been adopted to better understand the role of information in integrated manufacturing. Information is now considered a corporate asset. Creation, processing, movement, and security of information is therefore as important as that of the products/services of an enterprise. The case studies have helped in identifying the issues involved in developing an information system and supporting software framework for a manufacturing enterprise. The case studies have helped in refining an integration model, and identifying the characteristics desirable in modeling methodologies and tools. This paper describes a case study dealing with integrated manufacture of optical fiber products. A phased development and implementation approach was adopted where a small, manageable slice of the system is considered for the case study followed by functional modeling (IDEF0) and data flow modeling (Data Flow Diagrams). This identifies the pieces of information of interest. The information relationships are modeled using Extended Entity Relationship (EER) diagrams which are then mapped on to a relational model. The relational tables thus obtained were implemented on a commercial Database Management System. The functional constraints and application interfaces were then built using SQL and commercial application interface tools. The sections in the paper describe the functional models, data flow diagrams, EER diagrams, relational database design, and user/application interfaces developed for the system. Implementation experiences and observations are discussed followed by plans for the next phase of the system.
An Appraisal of Modeling Tools and Methodologies for Integrated Manufacturing Information Systems
Authors: Chadha Bipin , Jazbutis Gintas , Wang Ching-Yang , Fulton R. E. 
Published: April 2021

Abstract
Information systems are increasingly playing a pivotal role towards the integration of manufacturing functions. Several tools and modeling methodologies have been developed to facilitate the design and implementation of information systems for complex manufacturing environments. However, none of the methodologies or tools provide a comprehensive environment that can be used for the information system design from start to finish. The methodologies and tools are incomplete, and are inconsistent with each other. The IDEF (Integrated Computer Aided Manufacturing Definition) provides a set of methodologies that cover activity modeling, relationship modeling, and dynamic modeling that are consistent to each other, but still operate essentially in a stand alone fashion. Several CASE (Computer Aided Software Engineering) tools have been developed to implement these methodologies. The complexity and size of the manufacturing systems warrant the use of these tools. These tools can significantly increase the productivity of information system designers, but are still lacking in many respects as discussed in this paper. This study attempts to review the current state of the art in modeling methodologies and tools; to compare the existing data models; to explore the functionalities they offer; and to define a set of characteristics that are desirable in a modeling methodology for integrated information system design. The results are from a manufacturing point of view and were derived through case studies in manufacturing environments.
Scour Effects on the Structural Integrity of Offshore Wind Turbine Monopiles
Authors: Varelis George E. , Ai Jun , Kane Prasad , Ragheb Hossam , Dib Elie 
Published: April 2021

Abstract
Large diameter monopiles are widely used for the installation of offshore wind turbines in relatively shallow water depth applications. Monopiles are considered as a cost and time-efficient foundation solution, taking advantage of the experience gained from the Oil&Gas industry. Due to their relatively large diameter, monopiles are susceptible to scour effects that threaten their structural integrity and necessitate the application of high-cost mitigation measures. The mitigation measures are also associated with heavy environmental impact at the local subsea environment, as well as increased CO2 emissions for their application.
The present work examines the effect of scour on the structural integrity of monopiles using integrated simulation models that combine advanced finite element analysis (FEA) and computational fluid dynamics (CFD) techniques. A typical monopile geometry and North Sea representative metocean data are used in a case study. In this example analysis emphasis is given on the structural integrity deterioration resulting from the scour development over time. Advanced techniques are employed to simulate the soil-pile interaction. Furthermore, fluid-structure interaction effects due to the water flow around the monopile are examined using CFD techniques. Finally, fatigue life predictions of sensitive areas are conducted based on the “S-N methodology” and are enhanced by employing crack-growth analyses based on linear elastic fracture mechanics principles.
Ferric iron triggers greenalite formation in simulated Archean seawater
Authors: Hinz Isaac L. , Nims Christine , Theuer Samantha , Templeton Alexis S. , Johnson Jena E. 
Published: April 2021

AbstractSedimentary rock deposits provide the best records of (bio)geochemical cycles in the ancient ocean. Studies of these sedimentary archives show that greenalite, an Fe(II) silicate with low levels of Fe(III), was an early chemical precipitate from the Archean ocean. To better understand the formation of greenalite, we explored controls on iron silicate precipitation through experiments in simulated Archean seawater under exclusively ferrous conditions or supplemented with low Fe(III). Our results confirm a pH-driven process promoting the precipitation of iron-rich silicate phases, and they also reveal an important mechanism in which minor concentrations of Fe(III) promote the precipitation of well-ordered greenalite among other phases. This discovery of an Fe(III)-triggering iron silicate formation process suggests that Archean greenalite could represent signals of iron oxidation reactions, potentially mediated by life, in circumneutral ancient seawater.