bluuebunny/crossref_metadata_2025_split huggingface dataset:
Squeal of a Wheel Brake With Double Shoes
Authors: Nakai Mikio , Matsushita Takuya , Yokoi Masayuki 
Published: November 2020

Abstract
The purpose of this paper is to investigate the squealing mechanism of a wheel brake with double shoes to develop effective treatments for the reduction. Detailed observations reveal that the squeal frequencies are closely related to the natural frequencies of the system. These squeal frequencies coincide with the frequencies of instability obtained by a linear analysis of the system. It is demonstrated that squeals are induced by the coupling of the modes of the disk and both beams, two modes of a single beam and the modes of the disk and a single beam.
An Experimental Method to Identify the Effects of Joints on Structures Using Laser Vibrometry
Authors: Ma Xianghong , Vakakis Alexander F. , Bergman Lawrence A. 
Published: November 2020

Abstract
A technique based on laser vibrometry is outlined for identifying the effects of bolted joints on the structural dynamics. The method is based on the comparison of the dynamics of the bolted structure to that of a “baseline” structure; e.g., a structure with similar geometry and material characteristics but no jointed interface. Hence, under identical forcing conditions, the difference in the dynamics between the actual and baseline structures can be attributed solely to the joint interface effects. Non-contacting laser vibrometry is utilized to experimentally measure these differences in the structural responses at specific frequencies. A numerical algorithm is then developed to post-process the experimental data and identify the joint effects on the dynamics. The method provides estimates for the equivalent, frequency and amplitude dependent complex modulus of the joint interface. The laser scans of the mode shapes of the systems under consideration reveal interesting dynamic phenomena such as nonlinear effects due to micro-impacts at the bolted joint as well as effects due to non-proportional damping distribution.
Vibration Control of Rope-Sway of Elevator for High-Rise Building
Authors: Otsuki Masatsugu , Nakada Ryohsuke , Yoshida Kazuo , Nagata Kosoku , Fujimoto Shigeru , Munakata Tadashi 
Published: November 2020

Abstract
This study presents a synthesis method of a nonstationary optimal controller with a time-varying criterion function for reducing vibration of a time-varying object such as rope of elevator and crane. For time-varying object a stationary optimal control is little effective in reducing vibration. Hence, a nonstationary optimal control method with time-varying weightings on a control input and state values is applied to the time-varying object. As an illustration, the performance of reducing vibration with respect to the rope-sway problem on a high-rise building is examined through numerical calculation. Moreover, from the viewpoint of wave propagation, we propose a method of reducing vibration with wave-absorbing controller to remove the reflected waves. Finally, the performance of these nonstationary optimal and wave-absorbing controllers are compared with that of the stationary optimal controller for case that the structure is subjected to Kobe earthquake.
Load Identification Through Wavelet Parameterization
Authors: Nordberg T. Patrik 
Published: November 2020

Abstract
A novel approach based on a simulation error method using a wavelet parameterization is assessed. The present study focuses on the case where the load location is known a priori as it is for the interaction between the road profile and the tyre patch for an automotive vehicle. The proposed method is a time domain technique and the resulting inverse problem is discussed from the viewpoint of two different parameterization approaches. One approach concerns Fourier coefficients and the other advocates the use of wavelet coefficients. The discretized road profile is parameterized into coefficients which greatly reduces the number of unknown parameters in the resulting non-linear optimization problem. Sensor locations are chosen in accordance with the concept of identifiability. Finally, a numerical five degree-of-freedom system illustrates the applicability and performance of the method.
Parametric Studies on Moving Axle Load Identification
Authors: Yu Ling , Chan Tommy H. T. 
Published: November 2020

Abstract
This study addresses the effects of various parameters on moving axle load identification when vehicles move across a bridge. Main emphases are placed on evaluation of two solutions, pseudo-inverse (PI) and Singular value decomposition (SVD) solutions, to an over-determined set of equations established under the time domain method (TDM) and frequency-time domain method (FTDM). The effects of vehicle-bridge system parameters and of measurement system parameters on the TDM and FTDM are also investigated. Assessment results based on experiments in laboratory show that the TDM is a better and non-sensitive method. The SVD technique can effectively improve identification accuracy when using TDM and FTDM particularly in the case of the FTDM.
Open-Loop Control of a Flexible Manipulator With Two Links: Experimental Results
Authors: Mimmi G. , Frosini L. , Pennacchi P. , Rottenbacher C. 
Published: November 2020

Abstract
This paper describes the experimental results of an open-loop control technique applied to a flexible manipulator, specially designed for space duties, in order to reduce the residual vibrations at the end of the positioning. The experimental set-up is a system with two flexible links with rectangular section connected by rotational joints. First, the experimental identification of the system parameters has been carried out. Then, four different motion inputs have been implemented. The performances of these motion inputs are compared in terms of residual vibration at the end of the positioning. The experimental results confirm the effectiveness of the motion input pre-shaping technique in the reduction of the residual vibrations.
Modal Voltages and Distributed Signal Analysis of Conical Shells of Revolution
Authors: Tzou H. S. , Chai W. K. , Wang D. W. 
Published: November 2020

Abstract
Conical shells and components are widely used as nozzles, injectors, rocket fairings, turbine blades, etc. Dynamic and vibration characteristics of conical shells have been investigated over the years. In this paper, electromechanics and distributed sensing phenomena of a generic double-curvature shell and a conical shell are discussed, and governing sensing signal-displacement equations are derived. Spatially distributed modal voltages and signal generations of conical shells laminated with distributed piezoelectric sensor layers or neurons are investigated based on the Donnel-Mushtari-Valsov theory. Distributed modal voltages and their various signal components of conical shell models reveal that the dominating signal component among the four contributing signal components is the circumferential membrane component. This dominance is even more significant for lower shell modes and/or deep shells. In general, high strain regions result in high signal magnitudes. Accordingly, the spatially distributed signal patterns — the modal voltages — clearly represent the modal dynamic and strain characteristics of conical shells.
Non-Linear Behavior of Flexible Rotor-Bearing System of Aero Gas Turbine
Authors: Barad Sanjay , Giridhar R. K. , Rangan P. S. Kasthuri 
Published: November 2020

Abstract
Turbomachineries are generally high-energy systems operating at supercritical speeds. Often, nonlinear effects and latent instabilities are encountered during its operation which significantly influence the synchronous and asynchronous response of the rotor. The cause may be fluid film bearing, seal rubs, shaft joints and couplings, varied acceleration rates. Accordingly one may have a varied response behavior viz. Sub and super-harmonic oscillations, jump phenomenon, limit cycles, etc. The development phase of an aero gas turbine engine faces such challenges and these problems have to be addressed to achieve a flight-worthy engine.
The present paper discusses two case studies encountered during the development phase of an aero-engine in detail. First, is a case study of self-excited vibration caused due to oil inadvertently trapped in the internal cavity of hollow rotor and second, is the case demonstrating jump phenomena in case of a shaft with diaphragm couplings. The results acquired are well corroborated with the feedback and benchmarks. Wherever necessary, theoretical modeling has been resorted to validate the findings and get a better insight into the problem.
Effects of Initial Geometric Imperfections on Parametric Instability of Rectangular Plates
Authors: St-Georges Lyne , Ostiguy G. L. 
Published: November 2020

Abstract
The authors present a rational analysis of the effect of initial geometric imperfections on the dynamic behaviour of rectangular plates activated by a parametric excitation. This subject has been extensively investigated theoretically in the past, but no experimental data seems to be complete enough to validate the theory. The main objective of this investigation is to fill this void by performing experimental tests on geometrically imperfect plates, and to highlight the geometric imperfection’s influence on resonance’s curves. The study is carried out for an isotropic, elastic, homogeneous, and thin rectangular plate. The plate under investigation is subjected to the action of an in-plane force uniformly distributed along two opposite edges, is initially stress free and simply supported. Theoretical calculation and experimental tests are performed. In the theoretical approach, a dynamic version of the Von Kármán non-linear theory is used to evaluate the lateral displacement of the plate. The test rig used in the experimentation simulates simply supported edges and can accept plates with different aspect ratio. The test plates are pre-formed with lateral deflection or geometrical imperfections, in a shape corresponding to various vibration modes. Comparison between experimental and theoretical results reveals good agreement and allows the determination of the theory’s limitations. The theory used correctly describes the behaviour of the plate when imperfection amplitude is inferior to the plate thickness.
On the Response of a Shaken Cable-Suspended Mass
Authors: Virgin L. N. , Nichols J. M. , Simmons W. N. , Plaut R. H. 
Published: November 2020

Abstract
A small mass is suspended by two cables which are attached at angles to a rigid frame. The frame is shaken harmonically in the horizontal direction, causing the mass to respond typically in an erratic manner as the cables alternately become taut and slack. Since the cables are assumed to be inextensional, they provide an effective impulsive force to the mass as they become taut, causing an elastic rebound (which is modeled using a coefficient of restitution) [Plaut and Farmer, 2000]. The mass is assumed to be a point mass, and motion takes place within a vertical plane. One of the practical motivations for this work is the potential for using moored buoyant devices in an attempt to mitigate wave energy.
Simulations capture the unpredictable dynamic response of the mass, despite the relatively simplistic nature of the modeling. Special care is taken to accurately model the sudden transition when a cable instantaneously becomes taut. In the general case, the motion has chaotic characteristics and Poincaré sampling provides a useful diagnostic tool [Virgin, 2000].
The experimental results also show the complex nature of the behavior. The motion of the center of mass is obtained using a video camera and the IMAQ image processing package within LabVIEW. The results agree qualitatively with simulation.
Exploiting Results of Experimental Nonlinear Dynamics for Reduced-Order Modeling of a Suspended Cable
Authors: Alaggio Rocco , Rega Giuseppe 
Published: November 2020

Abstract
The role of experimental nonlinear dynamics in the proper reduced-order modeling of an elastic suspended cable undergoing finite-amplitude vibrations is analyzed. Two main aspects of the problem are addressed, namely (i) the number of discretizing functions to be used in a low-order finite-degree-of-freedom theoretical model in order to detect the main features of the observed nonlinear regimes, and (ii) the capability of different orthonormal function bases employed in a specific reduced-order model to reproduce complex regimes and bifurcation scenarios. Based on results of in-depth experimental investigations of a quasiperiodic scenario to chaos in a cable/mass system, a three-degree-of-freedom model of suspended cable is formulated, and different truncated bases of approximating functions are considered. They include standard linear normal modes, and proper orthogonal modal functions obtained from variable sets of experimental proper orthogonal modes identified in different intervals of the frequency range wherein the quasiperiodic scenario develops. The performances of the ensuing discretized models and their capability to qualitatively detect some main features of the actual regular and nonregular experimental responses are investigated through computer simulations.
The Influence of Nonlinear Boundary Conditions on the Nonplanar Autoparametric Responses of an Inextensible Beam
Authors: Arafat Haider N. , Nayfeh Ali H. 
Published: November 2020

Abstract
The nonplanar responses of a beam clamped at one end and restrained by nonlinear springs at the other end is investigated under a primary resonance base excitation. The beam’s geometry and the springs’ linear stiffnesses are such that the system possesses a one-to-one autoparametric resonance between the nth in-plane and out-of-plane modes. The beam is modeled using Euler-Bernoulli theory and includes cubic geometric and inertia nonlinearities. The objective is to assess the influence of the nonlinear boundary conditions on the beam’s oscillations. To this end, the method of multiple scales is directly applied to the integral-partial-differential equations of motion and associated boundary conditions. The result is a set of four nonlinear ordinary-differential equations that govern the slow dynamics of the system. Solutions of these modulation equations are then used to characterize the system’s nonlinear behavior.
Equations of Motion of an Aircraft Wing Modeled As a Composite Plate-Beam Model Including the Rigid-Body Motion
Authors: Emam Samir A. , Nayfeh Ali H. , Hendricks Scott L. 
Published: November 2020

Abstract
The equations of motion of an aircraft wing modeled as a composite beam are presented. The contribution of the rigid-body motion is taken into account; it affects the response of the wing, especially in maneuvers. The Hamilton principle is used to derive the equations of motion and the corresponding boundary conditions.
Nonlinear Dynamics of a Flexible Spinning Disc Subjected to Combined External and Parametric Excitation
Authors: Jana Anirban , Raman Arvind 
Published: November 2020

Abstract
This paper analyzes the nonlinear transverse vibrations of a clamped-free, uniform, flexible, annular disc, spinning about its axis with a constant angular velocity, and subjected to transverse loading from a pre-compressed spring. This is representative of a large class of loadings in rotating disc systems including air jet and electromagnetic excitation. Such loading can induce a simultaneous critical speed resonance and parametric instability. The disc is modelled by the Von Karman field equations, which are then discretized by a Galerkin projection onto a pair of 1-1 internally resonant modes. First order averaging is used to predict the dynamics of the forward and backward travelling waves (FTW and BTW). Equilibrium branches of the BTW amplitude and phase equations and their stability are studied for various combinations of parameters. The response is substantially different from that arising from a critical speed resonance or of a parametric instability alone. As many as five equilibrium solutions can coexist. Two distinct regimes of large amplitude response appear to exist depending on the relationship between the strength of the parametric excitation and the damping. The existence of these regimes underscores the subtle competition between critical speed resonance and parametric instability in such systems.
Studies on Codimension-3 Degenerate Bifurcations of the Flexible Beam
Authors: Zhang Wei , Wang Feng-Xia , Wen Hong-Bo 
Published: November 2020

Abstract
We present the analysis of codimension-3 degenerate bifurcations of a simply supported flexible beam subjected to harmonic axial excitation. The equation of motion with quintic nonlinear terms and the parametrical excitation for the simply supported flexible beam is derived. The main attention is focused on the dynamical properties of the global bifurcations including homoclinic bifurcations. With the aid of normal form theory, the explicit expressions of normal form associated with a double zero eigenvalues and Z2-symmetry for the averaged equations are obtained. Based on the normal form, it has been shown that a simply supported flexible beam subjected to the harmonic axial excitation can exhibit homoclinic bifurcations, multiple limit cycles, and jumping phenomena in amplitude modulated oscillations. Numerical simulations are also given to verify the good analytical predictions.
Perturbation Solution for Secondary Bifurcation in the Quadratically-Damped Mathieu Equation
Authors: Ramani Deepak V. , Rand Richard H. , Keith William L. 
Published: November 2020

Abstract
This paper concerns the quadratically-damped Mathieu equation:x..+(δ+ϵcos⁡t)x+x.|x.|=0. Numerical integration shows the existence of a secondary-bifurcation in which a pair of limit cycles come together and disappear (a saddle-node bifurcation of limit cycles). In δ–ϵ parameter space, this secondary bifurcation appears as a curve which emanates from one of the transition curves of the linear Mathieu equation for ϵ ≈ 1.5. The bifurcation point along with an approximation for the bifurcation curve is obtained by a perturbation method which uses Mathieu functions rather than the usual sines and cosines.
The Role of Nonlinear Strain-Displacement Relation on the Geometric Stiffening of Rotating Flexible Beams
Authors: Trindade Marcelo A. , Sampaio Rubens 
Published: November 2020

Abstract
Geometric stiffening of rotating flexible beams has been largely discussed in the last two decades. Several methodologies have been proposed in the literature to account for the stiffening effect in the dynamics equations. This work aims first to present a brief review of the open literature on this subject. Then, a general nonlinear model is formulated using a nonlinear strain-displacement relation. This model is then used to deeply analyze simplified models arising in the literature. In particular, the assumption of steady-state values for the centrifugal load is analyzed and its consequences are discussed.
Efficient Dynamic Simulation of Flexible Link Manipulators With PID Control
Authors: Arts Ronald G. K. M. , Jonker J. B. 
Published: November 2020

Abstract
For accurate simulations of the dynamic behavior of flexible manipulators the combination of a perturbation method and modal analysis is proposed. First, the vibrational motion is modeled as a first-order perturbation of a nominal rigid link motion. The vibrational motion is then described by a set of linear time-varying equations. Next, the number of degrees of freedom is reduced by applying a modal reduction technique. The proportional part of the control system is explicitly included in the modal analysis. The applicability of the method is demonstrated by simulating the controlled trajectory motion of a spatial flexible three-degree of freedom manipulator with PID control.
Power-Electronics Converters: A Field Rich in Discontinuities
Authors: Nayfeh Ali H. , Mazumder Sudip K. 
Published: November 2020

Abstract
We demonstrate the need for treating switching converters as discontinuous systems in order to properly analyze their dynamics and stability. We also outline some concepts related to the stability analysis of these variable-structure systems. Using these concepts, we investigate the stability and dynamics of a stand alone and an integrated DC-DC buck converter, which represents a nonlinear dynamical system under closed-loop operation. We compare the results with some of the existing ones, which are based on small-signal analyses, and demonstrate the shortcomings of the latter.
A Simple Method of Chaos Detection in Mechanical Systems With Discontinuities
Authors: Stefanski Andrzej , Kapitaniak Tomasz , Brindley John 
Published: November 2020

Abstract
A novel method of estimation of the largest Lyapunov exponent for discrete maps is introduced and evaluated for chosen examples of non-smooth dynamical systems. The method exploits the phenomenon of synchronization of two identical discrete maps when one of them is disturbed. Applications of the method for mechanical systems with discontinuities are presented and discussed.
Finding All Solutions of Non-Linear Oscillators via Interval Analysis
Authors: Karashima Kosuke , Nakai Mikio 
Published: November 2020

Abstract
When on finding all solutions of non-linear equations, there are some problems on the initial value. The problems remain in our developed R-B method which is one of the search procedures for finding all solutions of non-linear oscillators. The Krawczyk algorithm of the interval analysis for finding all solutions of nonlinear equations is useful for solving the initial value problem. In this paper, the Krawczyk algorithm is applied to the R-B method to find all solutions. The validity of this method is verified by an application to find all steady state periodic solutions in the Duffing equation.
Experimental and Simulational Investigation of Chaotic Behavior in Bilinear System With Clearance
Authors: Hossain Md. Zahid , Mizutani Kazuki , Sawai Hideki 
Published: November 2020

Abstract
Chaos and multiple periods have been demonstrated in this paper for harmonically excited bilinear spring and damping system with clearance. Experiment along with the simulation is considered for the investigation on the bilinear characteristics with clearance problem. The investigation is based on frequency response curves, and has been taken advantages of all data displaying techniques to understand the dynamics of the system. The position of the balance point of the system, spring stiffness ratio of the two spring of the bilinear model, and the extent of the clearance have been found very important factors to be shown chaotic motion. The effects on motion by the changing of the each factors are elaborately discussed in this study through the frequency response and the bifurcation in the both of the experiment and the simulation for a wide frequency region.
The Swing Vibration and Transverse Oscillation of a Cracked Rotor and the Intermittence Chaos
Authors: Meng G. , Qin W. Y. , Zhang T. 
Published: November 2020

Abstract
This paper studies the nonlinear dynamic response of a cracked rotor by taking the swing vibration of disc into consideration. The results show that if small crack appears, the frequency of transverse oscillation is synchronous with rotating speed ratio (Ω), and the frequency of swing vibration is NΩ (N = 1, 2 …). As the crack increases, the response becomes chaos in some range of Ω. The deeper the crack is, the wider the chaos range of Ω is. Routes to chaos include intermittence to chaos and quasi-period to chaos. When crack is fairly deep, there come some new resonance regions. In these regions, the response becomes infinity rapidly. The appearance of intermittence chaos is induced by the frequent frustration of stable oscillation, which is resulted from the continuous increase of swing amplitude. Unbalance parameter U is effective in suppressing chaos. Crack angle β can not affect the essence of response but can influence the amplitude of synchronous response.