bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Flexible Rotor on Flexible Bearing Supports: Part II — Unbalance Response
Authors: Vázquez José A. , Barrett Lloyd E. , Flack Ronald D. 
Published: February 2021

Abstract
An experimental study of the effects of bearing support flexibility on rotor unbalance response is presented. A flexible rotor supported by fluid film bearings on flexible supports was used with fifteen support configurations. The horizontal support stiffness was varied systematically while the vertical stiffness was kept constant. The support characteristics were determined experimentally by measuring the frequency response functions of the support structure at the bearing locations. These frequency response functions were used to calculate polynomial transfer functions that represented the support structure. The second critical speed of the rotor varied from 3690 rpm to 5200 rpm, depending on the support configuration. The predicted first critical speeds agree with the experimental data within −1.7%. The predicted second critical speeds agree with the experimental data within 3.4%. Predictions for the rotor on rigid supports are included for comparison.
Maximum Response of a Slow-Variant Mechanical System During Transition Through a Resonance
Authors: Balashov Dmitri , Irretier Horst 
Published: February 2021

Abstract
A new approach to the estimation of the maximum transient response of a mechanical system with slow-variant natural frequencies and linear viscous damping is worked out. Based on the modal decomposition, the vibration response of a system is modeled using a set of simple vibrators with slow-variant natural frequencies. The passage through a resonance which is induced by a sweep of the excitation frequency during run-up or run-down is studied. Exact asymptotic formulas for the maximum transient response and the corresponding excitation frequency are derived analytically, starting from the first Krylov-Bogoliubov approximation. The obtained formulas are tested numerically and compared to known approximations.
Laser Vibrometry: The Complete 6 Degree-of-Freedom Model of Target Velocity Sensitivity
Authors: Bell John R. , Rothberg Steven J. 
Published: February 2021

Abstract
This paper presents the first analysis of the velocity sensed by a single laser vibrometer beam incident in an arbitrary direction on a target that is of substantial interest in engineering — a rotating shaft requiring three translational and three rotational co-ordinates to describe its vibratory motion fully. Six separate vibration sets, each a combination of motion parameters, appear in the full expression for vibration velocity sensitivity and it is not possible to resolve individual motion components within each set by arrangement, or even manipulation, of beams. While unambiguous measurement of torsional vibration is possible, measurement of radial, pitch and yaw vibrations is only possible by post-processing. Application of the new theory includes straightforward extension to include measurements made with multiple beams, underlining the model’s versatility in enabling the vibration engineer to determine the vibration component sensitivity of any measurement with any beam orientation.
Vibration Analysis of an Induction Motor Under Electromagnetic Force
Authors: Iwatsubo Takuzo , Kawamura Shozo , Hayashi Yoshiyuki , Shiohata Koki 
Published: February 2021

Abstract
Three-phase induction motor causes an unstable vibration because of electromagnetic force. In this paper, a criterion for unstable vibration was introduced. To confirm this criterion, numerical integration was carried out and the results showed a good agreement with the unstable region obtained by the criterion. This criterion gives us the complete story about the stability for the case when the parameters e.g., phase current, air gap length etc. are changed. It was cleared that the natural frequency changes owing to the variation of phase current, and that the unstable vibration occurs when the frequency of power supply and the natural frequency (changed by current) are nearly the same. And it was also showed that the parameters can be classified into the categories whether they have influences on the stability or not.
A Model-Based Method for Balancing of Flexible Rotors Mounted on Oil-Film Bearings Without Trial Weight
Authors: Fritzen C.-P. , Gans P. , Wiese D. , Breitwieser M. 
Published: February 2021

Abstract
The following paper deals with a model-based method for unbalance identification. In contrast to conventional methods there is no need for the properties of the oil-film bearings to be known. First, the rotor is modeled as a conservative system in rigid bearings and the corresponding real mode shapes are calculated. The real motion of the rotor is represented by means of these mode shapes and the superimposed rigid-body motion of the rotor. The rigid-body motion is completely determined by the measured deflections in the oil-film bearings. Modal unbalances of the rotor are identified. Initial positive test results are presented in this paper.
Nonlinear Response of Rotors Supported on Squeeze Film Dampers
Authors: Ramesh Krishnaswamy , Kirk R. Gordon 
Published: February 2021

Abstract
The ability of a squeeze film damper (SFD) to attenuate the amplitude of vibration and to decrease the dynamic forces transmitted to the support system, makes it an attractive means of supporting turbomachinery. The main reasons for using a squeeze film damper on a rotor are to improve the dynamic stability and also to reduce the forces transmitted to the foundation. Generally the squeeze film damper ring is centered by a retainer spring. For linearized stability evaluation this is an acceptable assumption. While evaluating the forced response of a rotor having a squeeze film damper, the damper ring is usually assumed to be centralized in the clearance space through the entire running speed range. During the actual running condition the damper does not remain in the centered position and the damper ring tends to find its own eccentric position. This paper discusses the effect of this non-linear behavior of the damper and on the response. A overhung compressor is used as an example to illustrate the influence of the non-linear damper as compared to the centered damper assumption.
Comparison of Active and Hybrid Vibration Confinement With Conventional Active Vibration Control
Authors: Corr Lawrence R. , Clark William W. 
Published: February 2021

Abstract
This paper presents a numerical study in which active and hybrid vibration confinement is compared with a conventional active vibration control method. Vibration confinement is a vibration control technique that is based on reshaping structural modes to produce “quiet areas” in a structure as opposed to adding damping as in conventional active or passive methods. In this paper, active and hybrid confinement is achieved in a flexible beam with two pairs of piezoelectric actuators and sensors and with two vibration absorbers. For comparison purposes, active damping is achieved also with two pairs of piezoelectric actuators and sensors using direct velocity feedback. The results show that both approaches are effective in controlling vibrations in the targeted area of the beam, with direct velocity feedback being slightly more cost effective in terms of required power. When combined with passive confinement, however, each method is improved with a significant reduction in required power.
Active Control Machine Tool Chatter Piezo Ceramic Actuators in Tool Holder Shank
Authors: Håkansson L. , Claesson I. , Pettersson L. , Lagö T. 
Published: February 2021

Abstract
In the turning operation chatter or vibration is a frequent problem, which affects the result of the machining, and, in particular, the surface finish. Tool life is also influenced by vibration. Severe acoustic noise in the working environment frequently occurs as a result of dynamic motion between the cutting tool and the workpiece. These problems can be reduced by active control of machine-tool vibration. Adaptive feedback control based on the filtered-x LMS-algorithm, enables a reduction of the vibration by up to 40 dB at 1.5 kHz and by approximately 40 dB at 3 kHz. The active control performed a broadband attenuation of the sound pressure level by up to 35 dB. A significant improvement of the work-piece surface was also observed. In the active control of tool vibration a tool holder construction based on integrated high magnetostrictive actuators was used. However, both the physical features and properties of a active tool holder construction based on high magnetostrictive actuators and the fact that this type of actuators generally have a non-linear behaviour highly reduce its applicability to the general lathe and turning operation. Therefor, a new generation embedded active tool holder shanks based on piezo ceramic actuators have been developed. Based on spectrum estimates, both coherence spectrum and frequency response function estimates has been calculated for both the old tool holder construction and the new generation active tool holder shank. From the results it follows that the phase delay is smaller and the linearity of the new generation active tool holder shank are superior compared to the old technology. It is also obvious that physical features and properties of new generation embedded active tool holder shanks based on piezo ceramic actuators fits the general lathe application.
The Motion of a Flyline: Part B — Solutions
Authors: Hoffmann Jon A. , Reth Peov 
Published: February 2021

Abstract
The motion of a level flyline during the forward cast has been investigated for the case of line release from the rod. After the work input phase, the cast was considered to be composed of loop formation, line unrolling, loop dissipation and final descent phases. Solutions to the governing equations are presented. Input energy comparisons were made as a function of the parameters which control flyline motion. Line velocities during each phase, lengths of line released, and minimum initial line velocities required to complete loop dissipation have been predicted.
Energetics and Stability of Translating Media With an Arbitrarily Varying Length
Authors: Zhu W. D. , Ni J. 
Published: February 2021

Abstract
The dynamics of a class of translating media with an arbitrarily varying length is investigated. The tension in the media arising from their longitudinal accelerations is incorporated. The dynamic stability of the continuous media relative to the inertial and moving coodinate systems is studied from the energy standpoint. The exact expressions for the rates of change of energies of the media are derived and interpreted from both the control volume and system viewpoints. The monotonic behavior of the energy of vibration of the translating media during extrusion and retraction is affected by their jerks rather than accelerations. Examples including a robotic arm through a prismatic joint and an elevator hoist cable in a high rise building validate the analysis. In particular, the results explain an inherent “unstable shortening cable behavior” in elevator industry.
Modeling and Experimental Characterization of the Dynamic Behavior of Piezoelectric Recurve Actuation Architectures
Authors: Ervin James D. , Brei Diann E. 
Published: February 2021

Abstract
There are numerous applications that require fast actuators to deliver specific force and displacement output while fitting into confined spaces. A new family of piezoelectric actuators called Recurves exhibit high work per volume and have the extra benefit of having both the force-deflection performance and packaging tailorable to fit the requirements of a given application. The focus of this paper is the dynamic performance of this novel actuation scheme. Two dynamic models, a detailed transfer matrix model and a simpler rod approximation model, are presented to predict the steady state frequency response of a general Recurve actuator driving a mass and spring load. Results from a 23 design of experiments are given that validate these models and demonstrate the impact of the architectural design parameters on the dynamic behavior of the general Recurve actuator.
Tool Breakage Detection Using Statistical Moments
Authors: Ismail Fathy , Elbik Ali 
Published: February 2021

Abstract
On-line monitoring and detection of tool breakage is essential for highly automated machining centers. This paper presents a tool breakage method that utilizes statistical moments of the Beta distribution. The method has been applied successfully by the first author for the detection of tooth cracks in gears. It is extended here to the detection of chipped or broken teeth (inserts) in milling cutters. The method is assessed using cutting tests of steel workpieces employing Taguchi’s approach for statistical design of experiments. Results of these experiments show the Kurtosis of the Beta distribution to be a reliable tool breakage indicator that is insensitive to operating conditions and for typical amounts of tool radial runouts.
Gearbox Fault Detection Using Neural Networks Technology
Authors: Sun Qiao , Li Xiaolei , Xu Baoyun 
Published: February 2021

Abstract
This paper describes the application of neural networks to gearbox fault diagnosis. In order to increase learning speed of BP network, a modified learning algorithm was presented. Considering of the difficulty of choosing neural networks’ architecture, genetic algorithm was employed. The discussion of the effect of hidden layer nodes shows that with the increase of the number of nodes, the learning speed increase also yet result in poor generalization ability. The test of fault tolerance ability tells that neural networks have ‘bench type’ tolerance ability. This ensures that when signals were contaminated by noise or feature extraction methods were not effective, the result can still be acceptable.
To test the performance of the application of neural networks on gearbox fault diagnosis, experiments of single fault and multi-faults were both implemented and diagnosed by neural networks. The results were satisfied.
Impact Force Between Rolling Ball and Surface Fault in Damaged Ball Bearings
Authors: Rubini R. , Meneghetti U. 
Published: February 2021

Abstract
A great deal of research work has been dedicated in the last few decades to the development of refined and effective procedures for rolling bearing monitoring and diagnostics through vibration analysis. The basic observation is that sudden impact and consequent casing vibration take place every time a rolling ball overpasses a surface defect. As far as the authors know, little work has been focused on characterizing the impact force itself, i. e. determining its actual pattern and value. In this paper, the problem of identifying impact force between rolling balls and races is tackled experimentally. The force is recovered by inverse filtering of the casing acceleration. Results indicate the potential effectiveness of the method.
Vibrational Mechanics of Dry Friction and Impact Systems
Authors: Blekhman Iliya I. 
Published: February 2021

Abstract
The method of direct separation of motions and the general approach, called by the author “vibrational mechanics”, is developed so as to fit the problems of the effect of vibration on systems with dry friction and shock. The main idea of this approach lies in the transfer from the initial system of differential equations to the system, describing only the slow components of motion, most interesting for applications. It is these equations that are called the equations of vibrational mechanics. The advantages of this approach are especially significant in the case of systems with dry friction (Coulomb friction) and with unilateral constraints whose presence in case of vibration leads to multiple collisions of the system bodies. Instead of the not smooth system or with the discontinuous right sides there is a “smooth” system often of a lower order; an essentially non-potential system may be answered by a potential system.
Methods and approaches presented in the report are illustrated by the solution of two applied problems — a simplest problem of the transportation of a body along a rough vibrating surface and a problem on the motion of a body in space between the vibrating surfaces under periodic impacts. A short reference of investigations is given where the proposed approach is used or can be used quite effectively. In conclusion the main regularity is formulated which characterizes the action of vibration on systems with dry friction and impacts.
Mechanical Systems With Impacts: Comparison of Several Numerical Methods
Authors: Lamarque C. H. , Janin O. 
Published: February 2021

Abstract
We study the performances of several numerical methods (Paoli-Schatzman, Newmark, Runge-Kutta) in order to compute periodic behavior of a simple one-degree-of-freedom impacting oscillator. Some theoretical results are given and numerical tests are performed. We compare mathematical and numerical results using our simple example exhibiting either finite or infinite number of impacts per period. Comparison of exact and numerical solution provides a practical order for each scheme. We conclude about the use of the different numerical methods.
Tribometer for Dry Friction Measurement
Authors: Brandl Marc , Pfeiffer Friedrich 
Published: February 2021

Abstract
This paper deals with the measurement of dry friction. A tribometer was developed in order to identify both the sticking and the sliding coefficient of friction. The aim was to determine the so called Stribeck-curve of any material in contact. The design of the plant is presented. Avoiding errors in recalculating the coefficient of friction, a detailed model of the plant as a multi body system with motor feedback was generated. Advantages of the tribometer are shown in simulations. Some results of measurements in comparison with simulation results are presented.
Dynamic Analysis of Human Walking: Treadmills, Loss of Sensation, and Comparisons With Surrogate Data
Authors: Dingwell Jonathan B. , Cavanagh Peter R. , Sternad Dagmar 
Published: February 2021

Abstract
Correlation dimensions and average maximum finite-time Lyapunov (MFTL) exponents were used to examine the kinematics of continuous level walking in human subjects. Comparisons were made between overground (OG) and motorized treadmill (TM) walking in young healthy subjects and between diabetic neuropathic (NP) patients and healthy controls (CO) during overground walking. Surrogate data were used to examine the stochastic nature of the stride-to-stride variability seen in these walking patterns. There were three primary results. First, the motorized treadmill significantly constrained the neuromuscular control and normal movement kinematics of walking. Second, NP patients demonstrated greater correlation dimensions in their movement patterns and slowed their walking speeds to maintain maximum upper body stability during unrestricted walking over level ground. Third, stride-to-stride fluctuations in walking kinematics could be clearly distinguished from correlated Gaussian noise and demonstrated changes in their structure that were related to the loss of peripheral sensation.
Nonlinear Systems for Distances and Displacements Measurement
Authors: Mozuras Almantas , Kontvainaite Asta 
Published: February 2021

Abstract
In conventional methods, a physical system is considered more suitable for measurement purposes the greater its linearity is. However, purely linear converting systems are not available. The use of the linear features in the measurement process causes the drawbacks: systematic error due to nonlinear distortions, low signal-to-noise ratio, low measurement range, necessity to evaluate a great number of a priori parameters in order to obtain an absolute result, and low thermal stability because every a priori parameter itself has a temperature dependence. To exclude these drawbacks a method has been developed using nonlinearities in the base of displacements measuring process. The method is implemented using electretic, electrostatic, and photoelectric transducers. The contactless transducer is placed parallel to the surface of the object which displacements are measured. The transducer is driven to harmonic oscillations. Typical time intervals of the coded signal are measured. The object displacements are determined according to the changes of the typical time intervals. The method itself has no errors because approximations have been not made while deriving the relations. The source of errors is inaccurate registration of the start and end of the typical time intervals. The measurement is possible only if the physical system is nonlinear. The results of experimental investigations confirm the theoretical conclusions. The method allows one to increase measurement range significantly (for example, measurement range of the conventional capacitance meters is ∼10−2mm and in the proposed method measurement range using capacitance converter is about 1 mm).
Detection of Low-SNR Signals Using Dynamical Models Estimated With Higher-Order Data Moments
Authors: Péntek Áron , Kadtke James B. 
Published: February 2021

Abstract
We discuss a method for estimating nonlinear dynamical models from data, to construct a closed-form, few-parameter representation. The model coefficients are estimated using a Yule-Walker type equation involving higher-order correlations, which provides computational speed, numerical stability and noise robustness. We implement a multi-feature detector based on Mahalanobis distance and compute ROC curves for several signal classes. We show that the dynamical detectors’ performance can be improved significantly by increasing the sampling rate.
Nonlinear Dynamical Modeling of Sonar Signal Propagation
Authors: Katz Richard A. , Quazi Azizul H. 
Published: February 2021

Abstract
Sonar signal propagation has been traditionally modeled as a linear stochastic process. This research is a major departure from that classical viewpoint and is aimed at modeling acoustic signal propagation dynamics deterministically using the analysis tools of Nonlinear Dynamics and Chaos Theory. Advantages of using this new paradigm over traditional approaches to sonar modeling are demonstrated by simulating a linear frequency modulated (LFM) active sonar signal and two nonlinear variations of it. When nonlinear performance metrics called the mutual information (MI) and the differential radius (DR) are applied to both linear and nonlinear variants of the LFM signal, both metrics are found to be useful detectors of nonlinearity in a simulated acoustic time series. Next we demonstrate the DR technique, on real ultrasonic time series data, that was found to be useful for the diagnosis and treatment of a heart disease called atrial fibrillation. After summarizing results, we conclude with recommended future directions in applied nonlinear sonar signal propagation research.