bluuebunny/crossref_metadata_2025_split huggingface dataset:
Optimum Design of Magnetic Head Slider Under Static and Dynamic Operation Conditions of Hard Disk Drive
Authors: Hattori Yasuhisa , Hashimoto Hiromu , Ochiai Masayuki 
Published: February 2021

Abstract
The aim of this paper is to develop the general methodology for the optimum design of magnetic head slider for improving the spacing characteristics between head slider and disk surfaces under the static and dynamic operation conditions of hard disk drive and to present an application of the methodology to IBM 3380-type slider design. In the optimum design, the objective function is defined as the weighted sum of minimum spacing, maximum difference of spacing due to variation of radial location of head and maximum amplitude ratio of slider motion. Slider rail width, taper length, taper angle, suspension position and preload are selected as the design variables. Before the optimization of magnetic head slider, the effects of these five design variables on the objective function are examined by the parametric study, and then the optimum design variables are determined by applying the hybrid optimization technique combining the direct search method and the successive quadratic programming (SQP). From the results obtained, the effectiveness of optimum design on the spacing characteristics of magnetic head slider is clarified.
A Method for Analyzing Electromagnetic-Force-Induced Vibration and Noise From Motors
Authors: Shiohata Koki , Nemoto Kanako , Kobayashi Takashi 
Published: February 2021

Abstract
Electromagnetic force calculated by 2-dimensional analysis is transformed into exciting force for 3-dimcnsional structural-vibration analysis. And a procedure for modeling a vibrating structure is developed. Furthermore, a space-modal-resonance criterion, which relates electromagnetic force to structural vibration or noise, is introduced. In the structural-vibration analysis, the finite clement method is used; and in the noise analysis, the boundary element method is used. And vibration and noise of an induction motor are evaluated by using this criteria. Consequently, high-accuracy modeling is achieved and calculated noise almost completely coincides with that measured by experiments. And it is clarified that the-space-modal resonance criterion is effective on numerical simulation.
Vibration Analysis of Rotor-Bearing Systems With Internal Damping and Torsional Effects
Authors: Mohiuddin M. A. , Khulief Y. A. , Al-Juruf R. S. 
Published: February 2021

Abstract
This paper extends the model of the linearly tapered Timoshenko shaft finite element developed by the authors to include the effect of internal viscous and hysteretic damping. The resulting model accounts, in addition to internal damping, for bending, rotary inertia, gyroscopic moments, transverse shear deformations and torsion. The developed model has been programmed in a fairly general way to be applicable to a general rotor-bearing system where both anisotropic bearings and internal damping are present. Numerical results of modal characteristics as well as dynamic responses are generated.
A Model for Thermal Bending in Overhung Rotors
Authors: Balbahadur A. C. , Kirk R. G. 
Published: February 2021

Abstract
An approximate model for thermal bending caused by viscous lubricant shearing in overhung rotors has been developed. This model has been tested against a published theoretical model and an experimental study. It was found that the current model agreed well with both the other theoretical model and the experimental data.
Multi-Objective Optimum Design of Rotor-Bearing Systems With Dynamic Constraints Using Immune-Genetic Algorithm
Authors: Choi Byung-Gun , Yang Bo-Suk 
Published: February 2021

Abstract
An immune system has powerful abilities such as memory, recognition and learning how to respond to invading antigens, and is applying to many engineering algorithms in recent year. In this paper, the combined optimization algorithm (Immune-Genetic Algorithm: IGA) is proposed for multi-optimization problems by introducing the capability of the immune system that controls the proliferation of clones to the genetic algorithm. The new combined algorithm is applied to minimize the total weight of the shaft and the resonance response (Q factor), and to yield the critical speeds as far from the operating speed as possible. These factors play very important roles in designing a rotor-bearing system under the dynamic behavior constraints. The shaft diameter, the bearing length and clearance are chosen as the design variables. The dynamic characteristics are determined by applying the generalized FEM. The results show that the combined algorithm can reduce the weight of the shaft and improve the critical speed and Q factor with dynamic constraints.
Object Trajectory Tracking Control for Flexible-Link Multiple Manipulators
Authors: Sun Qiao 
Published: February 2021

Abstract
In this paper, we consider the object trajectory tracking control for flexible-link cooperating manipulators. In particular, we develop a stable inversion control law which is commonly known as the inverse dynamics control or the computed torque method for rigid manipulators. Difficulties in applying this method to the control of flexible link manipulators are due to the fact that the inverse dynamics system is generally unstable. As such, bounded actuator torques cannot be guaranteed. For multiple manipulators handling a common object, there are more actuators than the degrees of freedom of the system. Through decomposing the manipulator end-effector wrenches into resultant and internal force components, control laws are designed such that the internal forces are used to stabilize the system zero dynamics. Consequently, nonlinear inversion control can be applied for the object trajectory tracking control.
Time-Varying Cross-Spectra by Harmonic Wavelets for Soil Motion With Damage
Authors: Newland David E. , Butler Gary D. 
Published: February 2021

Abstract
Experimental records of acceleration time-history at several different heights in a centrifuged soil model have been analysed by the harmonic wavelet method to generate time-varying cross-spectra. These cross-spectra are compared with simulated results for a linear model. Local changes in the experimental cross-spectra, both amplitude and phase changes which are not present in the simulated results, are evidence of sudden changes in soil properties during dynamic testing.
The Motion of a Flyline: Part A — Governing Equations
Authors: Hoffmann Jon A. , Reth Peov 
Published: February 2021

Abstract
When fly fishing, a flyline is used to transport and launch a lure to the location of fish. Equations which describe the motion of a level flyline during the forward cast has been developed 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. The work-energy equation and Newton’s law were used to generate a finite element computational model for the forward cast in dimensionless form.
Bifurcations in the Dynamics of Two Coupled van der Pol Oscillators With Delay Coupling
Authors: Wirkus Stephen , Rand Richard 
Published: February 2021

Abstract
We investigate the dynamics of a system of two van der Pol oscillators with delayed velocity coupling. We use the method of averaging to reduce the problem to the study of a slow-flow in three dimensions. We study the steady state solutions of this slow flow, with special attention given to the bifurcations accompanying their change in number and stability. Our interest in this system is due to its relevance to coupled laser oscillators.
Order Reduction and Control of Large-Scale Linear Time Periodic Dynamical Systems
Authors: Deshmukh Venkatesh , Sinha S. C. 
Published: February 2021

Abstract
This paper provides methodology for designing reduced order controllers for large-scale, linear systems represented by differential equations having time periodic coefficients. The linear time periodic system is first converted into a form in which the system stability matrix is time invariant. This is achieved by the application of Liapunov-Floquet transformation. Then a system called an auxiliary system is constructed which is a completely time invariant. Order reduction algorithms are applied to this system to obtain a reduced order system. The control laws are calculated for the reduced order system by minimizing the least square error between the auxiliary and the transformed system. These control laws when transformed back to time varying domain provide the desired control action. The schemes formulated are illustrated by designing full state feedback and output feedback controllers for a five mass inverted pendulum exhibiting parametric instability.
A New Strategy for Detecting Gear Faults Using Denoising With the Orthogonal Discrete Wavelet Transform (ODWT)
Authors: Berri Sidi M. , Klosner J. M. 
Published: February 2021

Abstract
This paper investigates a new strategy for early detection of defects in a power transmission pair of spur gears. Sensitivity to local defects is enhanced by processing the signal as follows. The orthogonal discrete wavelet transform (ODWT) of the band-pass filtered averaged signal is first obtained. This is followed by thresholding in the wavelet domain, thereby removing the low amplitude noise contribution. The inverse wavelet transform then essentially reconstructs the component of the signal that is due to the defect. Experimental results demonstrate the efficiency of this procedure.
Point-Wise Dimension Estimate of Nonstationary, Multi-Episode, Time-Series and Application to Gearbox Signal
Authors: Lin D. C. , Augustine B. J. , Golnaraghi M. F. 
Published: February 2021

Abstract
Dimensions of nonstationary time series is studied. The nonstationarity is considered to be due to multiple episode where an episode is a piece of stationary time series. The dimension estimation algorithms in the literature can be naturally extended to study multi-episode time series by restricting the calculation on data segment of pre-determined length. Inevitably, more than one episode will be included in the segment. This work focuses on finding when such dimension estimate has a local interpretation as the dimension of the episode. It was found that the local interpretation is valid if there is a large enough difference in the autocorrelation time of the episodes. This is termed EES. In practice, the average first passage time of the reconstructed “orbit” can be used to determine EES. Numerical evidence of these results are given and the application to the mechanical gearbox signal are shown.
Experimental Investigation of Noise Sources in a Needle Roller Bearing System
Authors: Baldanzini Niccolò , Beraldo Federico , Carfagni Monica 
Published: February 2021

Abstract
An experimental investigation was undertaken to determine the causes of noise emission scatter in hosiery machines. Following the experimental measurement of the sound power levels, the hosiery machine’s mechanical system was assembled and tested with components of various sizes. The results indicated that the source of the noise emissions was a bearing’s outer race. Analysis of the outer race’s roundness profile in relation to vibrations provided accurate predictions of machine behavior. On the basis of a correlation between noise and vibrations, a practical method of online monitoring was developed.
Experimental Characterization Techniques for High Performance Hard Disk Drive Ball Bearing Spindle Motors
Authors: Chong Andrew , Yi Lu , Chen S. X. , Zhang Q. D. 
Published: February 2021

Abstract
The key task for the spindle motor in a hard disk drive is to provide stable, reliable and consistent turning power for many years to allow the hard drive to function properly. As hard disks become more advanced, virtually every component in them is required to do more & perform better, and the spindle motor is no exception. Increasing the rotational speed at which the platters spin means that the data can be read off the disk faster, and also reduces rotational latency, the time that the heads must wait for the correct sector number to come under the head. For this reason, there has been a push to increase the speed of the spindle motor. Since the launching of hydro-dynamic bearing spindle technology for high speed application will not be in due course, current ball bearing technology will still be around for a couple of years provided the spindle speed does not exceed around 15 Krpm. Therefore optimizing the steel balls in the spindle system is an alternative to deal with the ever-increasing performance requirements of the hard disk drive. To accomplish this, we have to understand the failure phenomenon in the spindle, thereby set test requirements to overcome the failure mechanism. These test requirements will help us to understand the performance characteristic and robustness of the spindle motor.
In this paper, the test requirements is set according to modal, load and vibration methods to quantify the hard disk drive ball bearing spindle motor.
Separating the Contributions in Localization Methods: A Technique to Enhance Identification of Damping Related Parameters
Authors: Algrain Hervé , Conti Calogero , Dehombreux Pierre 
Published: February 2021

Abstract
Finite Element Model Updating has for objective to increase the correlation between the experimental dynamic responses of a structure and the predictions from a model. Among different initial choices, these procedures need to establish a set of representative parameters to be updated in which some are in real error and some are not. It is therefore important to select the correct properties that have to be updated to ensure that no marginal corrections are introduced. In this paper the standard localization criteria are presented and a technique to separate the global localization criteria in family-based criteria for damped structures is introduced. The methods are analyzed and applied to both numerical and experimental examples; a clear enhancement of the results is noticed using the family-based criteria. A simple way to qualify the stability of a localization method to noise is presented.
Characterizing Damping and Restitution in Compliant Impacts via Linear Viscoelastic Models
Authors: Butcher Eric A. , Segalman Daniel J. 
Published: February 2021

Abstract
Strategies for characterizing damping and restitution in compliant impacts while eliminating the force discontinuities associated with the standard Kelvin-Voigt model are examined within the framework of linear viscoelasticity. A modification of the Kelvin-Voigt model as well as higher-order (Maxwell and standard linear) models are studied in an effort to satisfy the expected force-displacement boundary conditions. The restitution coefficients, energy losses per cycle, and equivalent linear damping ratios are then obtained analytically as functions of the dimensionless viscoelastic parameters which may be easily related to and obtained from experimentally measured restitution coefficients.
Torsional Vibrations of Laminated Beams: Comparison of Models
Authors: Nouri-Baranger Thouraya , Trompette Philippe , Shakhesi Said 
Published: February 2021

Abstract
Torsional dynamical behavior, natural frequencies and damping ratios of rectangular laminated beams are analysed through different displacement F.E. moderations which use: a semi-analytical finite element, an homogenization theory and a three dimensional analysis. All the results are compared to experimental values.
Thickness Deformation of Constrained Layer Damping: An Experimental Evaluation
Authors: Huang Peter Y. H. , Reinhall Per G. , Shen I. Y. , Yellin Jessica M. 
Published: February 2021

Abstract
Constrained layer damping can be an effective method to control transverse vibration of thin structures. The commonl used equation of motion governing the behavior of constrained layer damped Euler-Bernoulli beams, originally derived b Mead and Markus (1969), does not account for the relative transverse motion between the constraining layer and the base beam. When a soft viscoelastic layer or a stiff constraining layer is used, this relative transverse motion may become significant. To account for this motion, Miles and Reinhall (1986) developed a model that included the thickness deformation of the viscoelastic layer. The purpose of this paper is to demonstrate the existence of the thickness deformation through experiments and to investigate the validity of the Miles and Reinhall model. Experimental results show that the thickness deformation is significant in the high frequency range, and that the inclusion of the thickness deformation improves the accuracy of the analytical model.
Material and Microslip Damping in a Rotor Taking Gravity and Anisotropic Bearings Into Account
Authors: Wettergren Håkan L. 
Published: February 2021

Abstract
The paper is concerned with material and microslip damping in a rotor. The horizontal rotor is carried by anisotropic bearings, which means that the shaft feels three different frequencies, the rotational frequency and the difference and the sum of the rotational and vibrational frequencies. When material damping is studied these three frequencies lead to three different equivalent viscous damping constants and the dissipated energy can be solved analytically.
The rotor slot wedges in a turbine generator are used as an example of microslip damping. In this case the damping is non-linear and the results are obtained through numerical simulations.
The results show that these two different internal damping sources give both similarities and dissimilarities. The sign change and different magnitude of the dissipated energy running sub- or supercritical are the same. However the dissipated energy for material damping is not affected by gravity which microslip damping is.
A Nonlinear Tennis Racket Model With Modal Damping
Authors: Poggi Marc , Berlioz Alain , Dufour Régis 
Published: February 2021

Abstract
This article presents a model for predicting the response of a tennis racket under impact stress. Parameter identification and basic phenomena analysis are performed with mechanical models and experiments carried out on the frame, the ball, natural gut and aramid fiber string beds, and impacts of the ball on string beds supported by a rigid frame. The composite frame is modeled with beam finite elements and the string bed with a specific element able to take into account the nonlinear behavior arising from the string material and from the hardening geometric phenomenon. The frame is linear and is reduced with a dynamic condensation method and a modal basis enables the damping to be introduced by experimental modal damping ratios. Then experimental serves validate the predicted impact response of the tennis racket.
Velocity Jumps Induced by C0-Constraints
Authors: Glocker Christoph 
Published: February 2021

Abstract
Impacts in rigid body dynamics are characterized by the occurrence of impulsive forces leading to instantaneous changes in the velocities of the system. Such velocity jumps are usually associated with collisions of the bodies between each other or in interaction with the environment. Besides the collisions, there are other sources for velocity jumps, such as the restriction of a dynamic system to C0-submanifolds. This case will be discussed in the paper by an example. It will be shown that velocity jumps may occur, and that they may be interpreted as ordinary collisions at a priori unknown locations of the rigid body system. A solution method, based on a time scaling procedure, is proposed. This leads to equations, similar to those of classical dynamics, whereas the displacements are fixed. It will further be shown that any velocity jump which preserves kinetic energy may be interpreted as a reflection when the kinetic metric is used. This provides an alternative method to compute the post-impact velocities by a direct evaluation of the reflection law.
Impacts With Friction: Theory and Experiments
Authors: Pfeiffer Friedrich 
Published: February 2021

Abstract
Various models for impacts with friction have been proposed, the most successful ones taking into consideration a compression and an expansion phase in normal and tangential direction. Impulses are stored during compression and released with frictional losses during expansion. Stick-slip and detachment phenomena during the impact can be considered by complementarity rules.
A corresponding model for impacts with friction is presented and verified by measurements with an impact machine. In addition, some industry applications confirm the theory.
A Time Stepping Algorithm for Mechanical Systems With Unilateral Contacts
Authors: Stiegelmeyr Andreas , Pfeiffer Friedrich 
Published: February 2021

Abstract
The paper deals with a method to solve mechanical systems with unilateral contacts, numerically. The algorithm is based on a discretisation schema which fulfils the normal constraints on the position level. This prohibits drift phenomena and thus improves the numerical stability. Finally, the algorithm is applied to a roller coaster vehicle with 24 wheel–rail–contacts.
Identification of Impact Damping of Two Elastic Bodies
Authors: Hu Haiyan , Jin Dongping 
Published: February 2021

Abstract
The contact force of two impacting elastic bodies is widely modeled as the parallel combination of a nonlinear spring and a nonlinear dashpot. The restoring force of the nonlinear spring can be determined according to the Hertzian contact law in elasticity, while the model and corresponding parameters of the nonlinear damping force have to be identified through experiments. The current approaches of damping identification are based on the measured time histories of both contact force and relative approaching velocity of two impacting bodies. In this paper, a new technique is presented for the damping identification on the basis of measured time history of the contact force only. Hence, the tough problem of measuring the relative approaching velocity of two impacting bodies just before impact is removed. The efficacy test of the new technique is given in the paper through an example of identifying the impact damping of a pair of clamped beams.
A Note in Non-Intermittent Contact Problems of a Special Class of Ultrasonic Motors
Authors: Sattel Thomas , Hagedorn Peter 
Published: February 2021

Abstract
Contact problems play a key-role in ultrasonic motors. Our aim is the formulation of a contact model for stationary and non-stationary stator-rotor contact problems for a special class of non-intermittent ultrasonic motors. With the models proposed up to now, a detailed analysis of dynamic contact problems is only possible in a very limited manner. The simple contact model presented here can be used for numerical simulations and parameter studies and is verified by experimental studies carried out in our lab. First simulations show that, depending on the friction law, momentary perturbations can lead to self-excited vibrations in the rotor.