bluuebunny/crossref_metadata_2025_split huggingface dataset:
Semi-Active Vibration Isolation Control Using Feedforward Information of Disturbance
Authors: Yoshida Shigeaki , Yoshida Kazuo 
Published: February 2021

Abstract
Since the suppression of actuator power for active structural vibration control is an important problem, semi-active control methods receive much attention. In this paper, a new semi-active control method for the vibration isolation is presented. By taking the dynamics of disturbance into consideration, the optimal control method is applied to the augmented system that includes both the control object and the disturbance. By utilizing the obtained control law with a feedfoward link of disturbance, it is used for the semi-active control law based on the semi-active constraint of variable damper.
The control method was applied to the 4-DOF structural vibration isolation. The numerical analysis showed that the method has high control performance in a wide frequency range, and it is effective for the vibration isolation of building structures.
Design of Shape Memory Alloy Damper for Base Isolated Structure
Authors: Wilde Krzysztof , Gardoni Paolo , Fujino Yozo , Besseghini Stefano 
Published: February 2021

Abstract
Base isolation provides a very effective passive method of protecting the structure from the hazards of earthquakes. The proposed isolation system combines the laminated rubber bearing with the device made of shape memory alloy (SMA). The smart base isolation uses hysteretic behavior of SMA to increase the structural damping of the structure and utilizes the different responses of the SMA at different levels of strain to control the displacements of the base isolation system at various excitation levels. The performance of the smart base isolation is compared with the performance of isolation by laminated rubber bearings to assess the benefits of additional SMA damper for isolation of three story building.
Centrifugal Delayed Resonator: Theory and Experiments
Authors: Hosek Martin , Elmali Hakan , Olgac Nejat 
Published: February 2021

Abstract
A novel active vibration absorption technology, the Centrifugal Delayed Resonator (CDR), is presented as an efficient method for eliminating undesired torsional oscillations in rotating mechanical structures. The core idea is to reconfigure the dynamics of a damped centrifugal pendulum arrangement so that it behaves like an ideal real-time tunable absorber. This objective is achieved by applying a control torque based on proportional position feedback with variable gain and time delay. Fundamentals of the control strategy and its basic properties are explained, effects of the CDR absorber on a single-degree-of-freedom rotating structure are studied, and representative results of laboratory tests are presented. The strengths of this vibration control technology consist in complete elimination of a fundamental frequency component of undesired torsional oscillations, full effectiveness of vibration suppression in problems where the fundamental frequency of oscillations varies with time, very wide range of operating frequencies, complete decoupling of the feedback control from the mechanical properties of the rotating structure, comparatively simple implementation of the control algorithm, and fault-tolerant performance in the case of control failure.
Analytical and Experimental Investigation of an Impact Oscillator
Authors: Oestreich M. , Hinrichs N. , Popp K. , Budd C. J. 
Published: February 2021

Abstract
In the present paper a single-degree-of-freedom, periodically forced impact oscillator is investigated by numerics and experiments. At first the different types of motion and bifurcation diagrams are determined from experiments and compared to numerical results on the basis of the identified impact model. Also the nonsmooth third order system shows a rich bifurcational behaviour. On the basis of the identified nonsmooth model further analytical and numerical analysis can be applied. The Lyapunov exponents and the winding number are evaluated for the non-smooth system.
Periodic Response of Front End Accessory Drives With Dry Friction
Authors: Leamy Michael J. , Perkins Noel C. 
Published: February 2021

Abstract
Belt drives have long been utilized in engine applications to power accessories such as alternators, pumps, compressors and fans. Drives employing a single, flat, ‘serpentine belt’ tensioned by an ‘automatic tensioner’ are now common in automotive engine applications. The automatic tensioner helps maintain constant belt tension and to dissipate unwanted belt drive vibration through dry friction.
The objective of this study is to predict the periodic rotational response of the entire drive to harmonic excitation from the crankshaft. To this end, a multi-degree of freedom incremental harmonic balance (IHB) method is utilized to compute periodic solutions to the nonlinear equations of motion over a wide range of engine speeds. Computed results illustrate primary and secondary resonances of accessories and tensioner stick-slip motions.
Rattle Reduction of Automotive Component: A FEM Approach
Authors: Hsieh Shang-Rou , Shaw Steven W. , Borowski Victor J. , Her Jen Yaun , Moss Keith D. 
Published: February 2021

Abstract
Due to the continual diminishment of engine, power train and tire noise levels, squeak and rattle as become a primary source of undesired noise in automobiles. This article presents a finite-element-based methodology for the improvement of rattle performance of vehicle components. This approach attacks complicated nonlinear impact problems involving rigid and flexible structures by a rather indirect method that allows for the generation of design sensitivity information related to impact frequency and severity from large-scale computer models. This is done by adjusting the system parameters of a related linear problem in such a manner that the nonlinear system response is improved. For implementation purposes, it has been applied to study the rattle of the latch and corner rubber snubbers of a glove compartment. Results from the glove compartment study are summarized herein. Extensions to other rattle problems are also highlighted.
Impact Dynamics of a Supercavitating Underwater Projectile
Authors: Rand Richard , Pratap Rudra , Ramani Deepak , Cipolla Jeffery , Kirschner Ivan 
Published: February 2021

Abstract
We investigate the in-flight dynamics of a simplified model of a supercavitating body. In particular we are interested in the nature and frequency of the impacts which occur as the tail of the body touches the cavity walls. Referring to laboratory experiments conducted at Cal Tech in the 1950’s, we show that the tip force by the fluid is approximately directed along the length of the body. This gives zero moment about the body’s center of mass which leads us to assume that the body moves as if it were a moment-free rigid body pinned at its tip. To simplify the analysis, we assume that the body is not spinning about its symmetry axis. Then the motion between impacts is a plane motion with constant angular velocity. Using elementary fluid mechanics, we model the impact occurring when the tail touches the cavity walls, and we show that it is reasonable to assume that the impact is instantaneous with coefficient of restitution unity. Using this simplified model, we offer a simulation for typical parameters.
Smart Material Control Without Wire Leads or Electrodes: New Methods and Devices
Authors: Main John A. 
Published: February 2021

Abstract
Presented in this paper is a method for application of control signals to piezoelectric material patches that eliminates the need for both distributed electrodes and wire leads. The aim of this method is to provide a design solution for smart structural applications that require a very high spatial resolution over a relatively large area. The need for separate electrodes and leads is eliminated by depositing the control charges directly on the surface of the piezoelectric material using an electron gun. Both positive and negative electric displacements can be applied with an electron gun. This is accomplished by controlling the energy of the incident electron beam so that the secondary electron yield is either greater than or less than one. The spatial resolution of this control method is as small as the spot size of the electron beam, which in a focused beam may be as small as a few microns. One great advantage of this method is that it eliminates the need for discrete electrodes. This allows the control system design of a smart structural system to reside in signal processing rather than hardware.
Cyclic Deformation and Fatigue of a TiNi Shape-Memory Alloy Wire Subjected to Rotating-Bending
Authors: Tobushi H. , Hachisuka T. , Hashimoto T. , Yamada S. 
Published: February 2021

Abstract
The cyclic deformation and fatigue of a TiNi shape-memory alloy wire was studied by carrying out rotating-bending fatigue tests at various strain amplitudes, temperatures and rotational speeds in air and in water. The results were summarized as follows: (1) for strain amplitudes in the rhombohedral-phase transformation region, the fatigue life was longer than 107 cycles and the deformation properties did not change under cyclic deformation; (2) for the strain amplitudes in the martensitic transformation region, the fatigue life was shorter than 105 cycles and the higher the temperature, the shorter was the fatigue life; (3) the rotational speed did not affect the fatigue life in water but a higher rotational speed led to a shorter fatigue life in air.
Vibration Mode Localization in Randomly Disordered Weakly Coupled Two-Dimensional Systems
Authors: Xie Wei-Chau 
Published: February 2021

Abstract
In this paper, a general method of regular perturbation for linear eigenvalue problems is presented, in which the orders of perturbation terms are extended to infinity. The method of regular perturbation is applied to study vibration mode localization in randomly disordered weakly coupled two-dimensional cantilever-spring arrays. Localization factors, which characterize the average exponential rates of decay or growth of the amplitudes of vibration, are defined in terms of the angles of orientation. First-order approximate results of the localization factors are obtained using a combined analytical-numerical approach. For the systems under consideration, the direction in which vibration is originated corresponds to the smallest localization factor; whereas the “diagonal” directions correspond to the largest rate of decay or growth of the amplitudes of vibration. When plotted in the logarithmic scale, the vibration modes are of a hill shape with the amplitudes of vibration decaying linearly away from the cantilever at which vibration is originated.
Invariant NNM Manifolds for Studying Localized and Chaotic Dynamics of an Array Composed of STIFF/SOFT Elements
Authors: Georgiou Ioannis T. , Vakakis Alexander F. 
Published: February 2021

Abstract
This study concerns propagation of waves in a coupled array of soft/stiff oscillators. We show that the array supports a family of purely slow waves, including a solitary one, and a family of purely fast waves. The slow and fast waves interact to give rise to chaotically modulated slow/fast and fast/slow waves. Slow and fast waves are realized as two-dimensional invariant manifolds (normal modes) in phase space of a singular perturbation problem.
Gear Crack Detection With the Wavelet Transform
Authors: Boulahbal D. , Golnaraghi M. F. , Ismail F. 
Published: February 2021

Abstract
The wavelet transform has the ability to extract global information as well as localized small features from a given signal. This property makes it very well suited to the study of time-varying vibration signals generated by the operation of faulty gears. For a healthy and properly designed gear set, the vibration signal consists mainly of the gear meshing frequency component and its harmonics. Developing fatigue cracks introduce short-time transients that modulate both the amplitude and phase of the otherwise steady vibration signal. These transients are often difficult to detect with the traditional time-only or frequency-only techniques. Being a joint time-frequency distribution, the Wavelet transform allows one to look at the evolution in time of a signal’s frequency content. It thus appears to be the ideal tool to detect the localized transients. In this study, we use both the amplitude and phase maps of the wavelet transform to assess the condition of an instrumented gear test rig. With the proposed technique, simulated cracks as small as 20% of the tooth width at the root are easily detectable.
An Experimental Study of Vibrations of Nonideal Systems
Authors: de Mattos M. C. , Balthazar J. , Wieczorek S. , Mook D. 
Published: February 2021

Abstract
The vibrations excited by a rotating mass at the end of a cantilever beam are studied experimentally at the two universities given above. The mass is connected to the shaft of a DC motor with limited power. The response to changes in the applied voltage near resonance differs markedly from the response away from resonance: away from resonance, changes in the voltage applied to the motor are nearly linearly related to changes in the speed of the shaft and the amplitude of the motion remains small; near resonance changes in the voltage produce changes in the amplitude of the motion but have little or no effect on the speed of the shaft. Consequently, if the voltage is limited, it may not be possible to accelerate the motor-structure system through resonance. The Sommerfeld effect was observed, and it was found the jump associated with it could be extended by increasing the mass; however, the power needed to pass through resonance increased as the unbalanced mass increased. Regions of significantly modulated motions were found.
Friction Induced Vibrations in Aircraft Disk Brakes
Authors: Hagler Lisle B. , Reinhall Per G. 
Published: February 2021

Abstract
This paper presents a detailed analysis of the dynamic behavior of a single rotor/stator brake system. Two separate mathematical models of the brake are considered. First, a non-rotational model is constructed with the purpose of showing that friction induced vibration can occur in the stator without assuming stick-slip behavior and a velocity dependent friction coefficient. Self-induced vibrations are analyzed via the application of the method of multiple scales. The stability boundaries of the primary resonance, as well as the super-harmonics and sub-harmonics are determined.
Secondly, rotational effects are investigated by considering a mathematical brake model consisting of a spinning rotor engaging against a flexible stator. Again, a constant friction coefficient is assumed. The stability of steady whirl is determined as a function of the system parameters. We demonstrate that only forward whirl is stable for no-slip motion of the rotor.
The interactions between chatter, squeal, and rotor whirl are investigated through numeric simulation. It is shown that rotor whirl can be an important source of the torsional oscillations (squeal) of the stator and that the settling time to no-slip decreases as the ratio of the stator to rotor stiffness is increased.
Analysis of Ball Bearing Vibrations Caused by Outer Race Waviness
Authors: Ono Koichiro , Okada Yohji 
Published: February 2021

Abstract
Even with the use of highly efficient machine, the manufacturing of rolling elements bearings still results in defective bearings. The defects could be on the race track or the rolling elements. A common problem with defective bearing is the generating waviness on the outer race track during the manufacturing process. The vibrations caused by rolling elements rolling over the waviness surface is transmitted to the passenger cabin and produced unwanted noise. In this paper an analytical study was first undertaken to evaluate the effect of waviness number, radial gap and shaft unbalance on the vibration spectrum. Experimental investigation was carried out to confirm the analytical study. The experimental results agreed very well with the numerical analysis.
Analysis of Models for Torsional Vibration of Shaft System With Planetary Gearing
Authors: Sun Jinghui , Liu Lee , Patten William N. 
Published: February 2021

Abstract
The kinematics of planetary gearing are complex; thus, making it difficult to build an effective dynamic model. In this paper, a single-mass model of a planetary gear and shaft system is developed to study the torsional vibration of the mechanism. Two new models of the system are proposed: (a) a fictitious co-planar model and (b) an equivalent shaft model. The results from the calculations and analyses using these models indicate that: 1) the single-mass model and the general rotary model are both limited, either mathematically or geometrically; 2) the fictitious co-planar model includes all of the geometric and dynamic parameters of the general rotary model, and it can be connected with the shaft system easily; and 3) using a mathematical treatment, the equivalent shaft model is demonstrated to be the most useful and most effective model for the calculation of torsional vibration of a shaft and planetary gear train.
Clearance Effects on Spiral Vibrations due to Rubbing
Authors: Childs Dara W. , Jordan Leland T. 
Published: February 2021

Abstract
Kellenberger’s (1980) model for spiral vibrations due to rubbing is extended to include the effects of a radial clearance at the rub location. Black’s (1968) model is used to incorporate the influence of clearance. Clearances at the rub location introduce a nonlinearity and are shown to modestly improve stability. A review of Kellenberger’s model reveals that his equations defining the growth of the shaft due to rubbing are only correct if two (previously unspecified) conditions are met, and simulations show that both conditions are violated. However, an alternative, “kinematically-correct”, model yields results which are significantly less consistent with the observed behavior of spiral vibrations than Kellenberger’s original model.
Modal Analysis of a Rotating Shaft-Disk-Blades System With a Cracked Blade
Authors: Wu Ming-Chuan , Huang Shyh-Chin 
Published: February 2021

Abstract
The dynamic behavior of a rotating shaft-disk-blades system containing a cracked blade is investigated. With the crack released energy, the flexibility due to crack is evaluated. An energy principle in conjunction with the assumed-mode method is applied to yield the discrete equations of motion. Numerical examples are given for cases with between two and five symmetrically arrayed blades. The results show that there exist both torsion-bending coupled modes and blade-coupling modes, which occur at repeated frequencies. When there is a cracked blade, the frequencies of torsion-bending coupled modes decrease due to the crack, and blade-coupling modes have the phenomena of frequency bifurcation. Finally, the effects of shaft speed on the natural frequencies are illustrated.
In-Plane Bending Modal Analysis of Circular Rings and Ring Segments: Use of ‘Exact’ Dynamic Stiffness Matrix
Authors: Azimi Saeed Z. 
Published: February 2021

Abstract
The ‘exact’ dynamic stiffness matrix for the case of a circular ring segment, considering the in-plane bending vibration only, is presented and its use for different situations of classical boundary conditions is discussed. In this formulation one can also include the flexibilities of the end supports in the radial and rotational directions and/or consider the flexible or rigid intermediate supports for a multi-span structure. Dynamic analysis of structures composed of circular ring segments with different load applications can also be investigated using this formulation.
The Response of a Nonconservative Distributed System to a Moving Oscillator
Authors: Pesterev Alexander V. , Bergman Lawrence A. 
Published: February 2021

Abstract
The problem of calculating the response of a nonconservative distributed parameter system of a general type excited by a moving concentrated load is investigated. A method of solution based on the expansion of the response in a series in terms of complex eigenfunctions of the distributed system is proposed. A set of ordinary differential equations in the time-dependent coefficients of the expansion is established first, in terms of the unknown force acting on the continuum from a moving vehicle, which allows one to investigate different models of concentrated loads. Then, for the case of a conservative oscillator moving with an arbitrarily varying speed, the coefficients of the equations are obtained in explicit terms.
An Experimental Method to Determine Poisson’s Ratio in a Small Beam Subject to Seismic Excitation
Authors: Caracciolo Roberto , Gasparetto Alessandro , Giovagnoni Marco 
Published: February 2021

Abstract
An experimental method to determine Poisson’s ratio in a small beam subject to seismic excitation is presented. Poisson’s ratio is computed by measuring longitudinal and transverse strains by means of electric strain gauges. A first set of tests is carried out with different materials, and it is observed that the measured Poisson’s ratio decreases with frequency. However, to determine whether the observed decrease is true or it is due to an error caused by the plate effect of the beam, a second set of tests at different temperatures is carried out. Then, by applying the reduced variables method, a unique plot for Poisson’s ratio on a much broader frequency range is obtained, which allows to state that the decrease of Poisson’s ratio is true. An iterative procedure is described, which has been developed to gather the curves at different temperatures in a master curve.
On the Free Vibrations of a Whirling Rod
Authors: O’Reilly Oliver M. , Turcotte Major Jeffrey S. 
Published: February 2021

Abstract
In this work, the problem of a whirling rod is examined. The governing equations for the steady motion of the rod and small amplitude vibrations superposed on the steady motion are formulated and discussed. This formulation uses the theory of a directed or Cosserat rod which was developed by A. E. Green, P. M. Naghdi and several of their co-workers. The present work also involves extensions to recent work by O’Reilly on properly invariant approximate theories.
Free and Forced Vibration of an Axially Moving String With an Arbitrary Velocity Profile
Authors: Zhu W. D. , Guo B. Z. 
Published: February 2021

Abstract
The exact response of an axially moving string with an arbitrary velocity profile is determined under general initial conditions and external excitation. In terms of the curvilinear characteristic coordinates the time-dependent governing equation reduces to one with constant coefficients. The domain of interest in the characteristic coordinate plane is bounded by two monotonic curves with the same shape corresponding to the spatial boundaries of the string. Solution of the transformed equation is derived for the free and forced responses. The displacement of the free response is shown to be bounded under arbitrary variation of the transport speed in the subcritical regime. Parametric resonances do not exist. The method is demonstrated on two illustrative examples with piecewise constant and sinusoidal accelerations.
Frequencies of Axial Vibrations of the Beam
Authors: Cveticanin Livija 
Published: February 2021

Abstract
In this paper the free longitudinal vibrations of the beam on which the strong nonlinear force of Winkler type acts are analyzed. The vibrations are described with a second order strong nonlinear partial differential equation. Various approximate analytical methods for solving this equation are developed in the paper. The lowest frequency of vibration obtained by the suggested method are compared. It can be seen that some differences appear.