bluuebunny/crossref_metadata_2025_split huggingface dataset:
Application of Robust Two Degree-of-Freedom Control Using μ-Synthesis to the Vibrations in Vehicle Engine-Body System
Authors: Yang J. , Suematsu Y. , Shimizu S. , Okumura Y. 
Published: February 2021

Abstract
This paper presents a robust active control for the vehicle engine-body system. The robust two degree-of-freedom (2DOF) controller is formed by combining a feedback (FB) controller with a feedforward (FF) controller. The feedback controller is designed by μ-synthesis to attenuate the effect of engine vibration disturbance by modeling the vehicle engine-body system as a nominal four degree-of-freedom vibration system with the parameter variations and the unmodeled dynamics. Based on filtered-X LMS algorithm, an active vibration controller is used as a feedforward controller to improve control performance further. To demonstrate the effectiveness of the control scheme, we have made some experiments in an experimental device, which is designed to imitate real vehicle engine-body system.
Theoretical and Experimental Finite Forced Dynamics of a Cantilever Beam: Dynamic Instability and Modal Coupling
Authors: Benedettini Francesco , Di Egidio Angelo 
Published: February 2021

Abstract
The 3-d dynamics of a cantilever beam undergoing large displacements under a sinusoidally varying, concentrated, vertical force at its free end is analyzed. The pde’s of the motion are obtained by using the Hamilton principle and then a reduced 3 degree-of-freedom model is obtained using in a Galerkin discretization, three eigenfunctions of the linearized model. A path following procedure is used to describe the global dynamic behavior in the excitation control parameter plane. The results obtained using the simple 3 d.o.f. analytical model are then compared with those of an experimental steel model of the cantilever. The regions of instability of the unimodal planar solution in which the nonlinear modal coupling excites the torsional component are studied; the planar motion usually looses stability via Hopf bifurcations after which quasi-periodic and/or chaotic motions are found. Inside the regions in which the system shows a complex time-evolution the complexity-level of the response is analyzed using, for the experimental model, a time series analysis tool.
Sine Sweep and Steady-State Response of a Simplified Solar Array Model With Nonlinear Support
Authors: Fey Rob H. B. , Winter Berend , Wijker Jaap J. 
Published: February 2021

Abstract
In this paper the dynamic behaviour of a multi degree of freedom beam model of a solar array structure is investigated both experimentally and numerically. The beam is supported by one nonlinear element, a so-called snubber. This snubber can only take compressive forces. Two types of excitation are applied and compared: sine sweep excitation (with different sweep rates and directions) and steady-state excitation. Emphasis lies on the investigation of the dynamic behaviour of the system under prestress, which implies softening behaviour at the time when snubber and beam loose contact. The system displays rich nonlinear dynamic behaviour: multiple solutions (hysteresis loop), superharmonic resonances and subharmonic, quasi-periodic and chaotic solutions. Good correspondence between experimental and numerical results has been found.
Reflexive Control of Slipping in an Anthropomorphic Bipedal Locomotion Robot
Authors: Healy T. A. , Reisinger K. D. 
Published: February 2021

Abstract
To be successful a bipedal locomotion system will be required to robustly traverse terrain with unknown and varying surface conditions. Even in made-for-human environments a broad range of surface conditions may be encountered and slipping is a very real and serious concern. Since a priori detection and avoidance is not practical, a robust system must detect and respond to the unexpected event after it has occurred and before control is lost. This must be accomplished in an extremely limited time frame. This paper proposes the use of human-like reflexes to enable robust recovery from slipping. The proposed algorithm seamlessly integrates reflexive responses into the nominal control system. Effectiveness of the algorithm is demonstrated via simulation results.
Post-Critical Response of an Axially Moving Beam
Authors: Pellicano Francesco , Vestroni Fabrizio 
Published: February 2021

Abstract
In this paper the dynamic response of a simply supported traveling beam, subjected to a pointwise transversal load, is investigated. The motion is described by means of a high dimensional system of ordinary differential equations with linear gyroscopic part and cubic nonlinearities obtained through the Galerkin method. The system is studied in the super-critical speed range with emphasis on the stability and the global dynamics that exhibits special features after the first bifurcation. A sample case of a physical beam is developed and numerical results are presented concerning bifurcation analysis and stability, and direct simulations of global postcritical dynamics. In the supercritical speed range a regular motion around a bifurcated equilibrium position becomes chaotic for particular values of frequency and force. The bifurcation diagram for varying force intensity is shown, it can be noticed that a chaotic motion occurs in a wide range of the forcing parameter, co-existing with a 3T periodic solution in a limited window.
Global Analysis of the Double Impact Oscillator Dynamics
Authors: Peterka František 
Published: February 2021

Abstract
The double impact oscillator represents two symmetrically arranged single impact oscillators. It is the model of a forming machine, which does not spread the impact impulses into its neighbourhood. The anti-phase impact motion of this system has the identical dynamics as the single system. The in-phase motion and the influence of asymmetries of the system parameters are studied using numerical simulations. Theoretical and simulation results are verified experimentally and the real value of the restitution coefficient is determined by this method.
Control of a Quarter-Car Model With Variable Damping
Authors: Verros G. , Natsiavas S. , Stepan G. 
Published: February 2021

Abstract
Dynamics of a strongly nonlinear quarter-car model is investigated. The nonlinearity is due to a control strategy which selects the damping coefficient of the car suspension in a way that the resulting semi-active system approximates the performance of an active suspension system designed to produce sky-hook damping. According to this control strategy, the damping coefficient switches between two different positive values, leading to a piecewise linear dynamical model. For this model, the equation of motion is first presented in a general normalised form. Then, an appropriate methodology is applied for obtaining exact periodic motions for the case of forcing resulting from a road with harmonic profile. This methodology is based on employing the exact solution form within response intervals where the damping coefficients remain constant. The unknowns of the problem are then determined by imposing a set of periodicity and matching conditions. The stability analysis of the located motions is also performed by applying a method which is suitable for piecewise linear systems. Next, this analysis is applied and representative numerical results are obtained. Namely, response diagrams are presented, showing the effect of the important system parameters on the existence, amplitude and stability properties of various branches of periodic solutions. The results are also compared to those of the conventional suspension systems, including passive bilinear shock absorbers.
Influence of Bearing Compliance on Long-Term Nonlinear Rotordynamics
Authors: van de Vrande Bram L. , de Kraker Bram 
Published: February 2021

Abstract
This paper presents the influence of bearing liner compliance on the long-term dynamics of a symmetric rigid rotor on short journal-bearings. Both balanced and unbalanced rotors are investigated for different values of the compliance, using the (nondimensional) rotor speed as the bifurcation parameter. The results show a decrease in the onset speed of instability of the balanced rotor, and a considerable influence on the 1/2-subharmonic solutions in case of unbalance excitation.
Nonlinear Vibro-Acoustic Response of a Metal Sample With a Discontinuity-Like Defect As Related to Damage Detection Problems
Authors: Zaitsev Vladimir Yu. , Sas Paul 
Published: February 2021

Abstract
The nonlinear vibro-acoustic response of solid samples containing quite a small amount of defects can be anomalously high in magnitude compared to the case of undamaged intact solids. Functional dependencies of the nonlinear effects exhibit rather interesting behavior. In this paper, experimental results on nonlinearity-induced cross-modulation of a high-frequency (HF) f = 15...30 kHz signal by a low-frequency (LF) F = 20–60 Hz vibration in an aluminium plate with a small single crack are reported. Comparison with a reference sample (the identical plate without a crack) has proven that the presence of such a small defect can be easily detected due to its nonlinear manifestations. It is demonstrated that under proper choice of the sounding signal parameters, the effect level can be so pronounced that the amplitude of the modulation side-lobes originated due to the nonlinearity exceeds the amplitude of the fundamental harmonic of the HF signal. Main physical features of the observed phenomena are pointed out, their physical explanation is suggested and some simulation results are also presented.
Slowly Modulated Traveling Waves in Circular Plates Spinning Near Critical Speed
Authors: Raman Arvind , Mote C. D. 
Published: February 2021

Abstract
Motivated by observations of low-frequency “snaking” motions of circular sawblades encountered during cutting operations, we study the large amplitude transverse vibrations of an imperfect, flexible, lightly damped, circular plate spinning near a critical speed resonance. Of particular interest are the effects of imperfection and the conditions under which low-frequency, amplitude and phase modulated traveling waves, that is snaking motions, can arise in this system. This is accomplished through a local bifurcation analysis of the first-order averaged equations governing the nonlinear interaction, under conditions of a 1 : 1 internal resonance, of a pair of backward and forward traveling waves. Experiments are performed at reduced ambient pressure on a rotating steel disk with imperfection induced through attached point masses, to confirm qualtitatively the analytical predictions. The experiments also indicate an unexplained, additional superposed slow motion on all solution branches.
Internal Resonance Phenomena of an Asymmetrical Rotating Shaft: Critical Speed of Twice the Major Critical Speed
Authors: Ishida Yukio , Inoue Tsuyoshi 
Published: February 2021

Abstract
Unstable vibrations appear in the vicinities of several critical speeds in asymmetric rotor systems with nonlinear spring characteristics. However, when the natural frequencies satisfy internal resonance relation exactly or approximately, these phenomena may change remarkably. In this paper, such internal resonance phenomena of an asymmetric shaft-disk system are studied theoretically and experimentally. The changes in nonlinear phenomena during the transition from the system with internal resonance to the system with no internal resonance are also investigated.
Non-Smooth Dynamics and Non-Classical Bifurcations in Impulse-Impact Oscillators
Authors: Lenci Stefano , Rega Giuseppe 
Published: February 2021

Abstract
Some aspects of the nonlinear dynamics of an impulse-impact oscillator are investigated. After an initial description of the prototype mechanical model used to illustrate the results, attention is paid to the classical local and global bifurcations which are at the base of the changes of dynamical regime.
Some non-classical phenomena due to the particular nature of the investigated system are then considered. At a local level, it is shown that periodic solutions may appear (or disappear) through a non-classical bifurcation which involves synchronization of impulses and impacts. Similarities and differences with the classical bifurcations are discussed.
At a global level, the effects of the non-continuity of the orbits in the phase space on the basins of attraction topology are investigated. It is shown how this property is at the base of a non-classical homoclinic bifurcation where the homoclinic points disappear after the first touch between the stable and unstable manifolds.
Analysis and Simulation of Radial Chatter in Drilling and Reaming
Authors: Metzler Sandra A. , Bayly Philip V. , Young Keith A. , Halley Jeremiah E. 
Published: February 2021

Abstract
At high cutting speeds, self-excited regenerative vibrations (“chatter”) of drilling and reaming tools may occur. Chatter is an instability in which oscillation of the tool causes variation in the chip load, which in turn amplifies tool motion. This phenomenon is well known in turning and milling, and has also been studied in boring. In drilling and reaming, both axial motion and radial (bending) motion of the tool may affect the chip load, but dynamic stiffness is often much higher axially. Analysis of radial chatter requires consideration of at least two degrees of freedom as well as consideration of the special geometry of the drilling and reaming tools. In this paper we find analytical stability boundaries for drilling; the analysis extends a boring model developed by Li and Ulsoy (1998). We also show that it is necessary to use a different approach to predict instability in reaming. Stability boundaries for reaming were found by a method proposed for milling by Altintas and Budak (1995). A dynamic time-domain simulation suitable for both drilling and reaming was used to confirm analytical predictions and obtain qualitative insight into the instabilities, which involve both forward and backward whirling modes.
Parameter Estimation in a Nonlinear Vibrating System Using an Observer for an Extended System
Authors: Chatterjee Anindya , Cusumano Joseph P. 
Published: February 2021

Abstract
We present a new observer-based method for parameter estimation for nonlinear oscillatory mechanical systems where the unknown parameters appear linearly (they may each be multiplied by bounded and Lipschitz continuous but otherwise arbitrary, possibly nonlinear, functions of the oscillatory state variables and time). The oscillations in the system may be periodic, quasiperiodic or chaotic. The method is also applicable to systems where the parameters appear nonlinearly, provided a good initial estimate of the parameter is available.
The observer requires measurements of displacements. It estimates velocities on a fast time scale, and the unknown parameters on a slow time scale. The fast and slow time scales are governed by a single small parameter ϵ.
Using asymptotic methods including the method of averaging, it is shown that the observer’s estimates of the unknown parameters converge like e−ϵt where t is time, provided the system response is such that the coefficient-functions of the unknown parameters are not close to being linearly dependent. It is also shown that the method is robust in that small errors in the model cause small errors in the parameter estimates.
A numerical example is provided to demonstrate the effectiveness of the method.
Compact Nonlinear Signal Representation in Machine Tool Operations
Authors: Bukkapatnam Satish T. S. 
Published: February 2021

Abstract
Effective processing and compact representation of signals from manufacturing processes is necessary for sensor-based modeling (Venuvinod 98), and real-time diagnosis and control purposes. However, the processing and the representation of signals emerging from nonlinear processes remains largely ignored. This article focuses on the compact representation of near-periodic signals (signals containing a dominant period), emerging from nonlinear dynamical systems with known initial conditions. Such signals commonly occur in machine tool operations. We propose the concept of pseudoprobability space and provide an approach based on lifting scheme to customize wavelet filters to compactly represent near-periodic signals, and validate the approach for acoustic emission signals emanating from machine tool operations. Here, we focus on the concentration of the reconstructed signal using the coefficients from lifting on a single scale. We provide a detailed assessment of our approach, including a detailed study of the relationship between the discrete wavelet transform (DWT) and the discrete-time wavelet transform (DTWT). We derive the pyramid algorithm for DTWT with non-biorthogonal wavelets, which is necessary for our assessment. Our numerical experiments establish the viability of our approach.
Cancelling of Self-Excited Vibrations by Means of Parametric Excitation
Authors: Tondl Aleš , Ecker Horst 
Published: February 2021

Abstract
The possibility of cancelling self-excited vibrations of a mechanical system using parametric excitation is discussed. A two-mass system is considered, with the top mass excited by a flow-generated self-exciting force. The parameter of the connecting stiffness between the base mass and the foundation is a harmonic function of time and represents a parametric excitation.
For such a system general conditions for full vibration cancelling are derived and presented. By means of numerical simulation the system is investigated for several sets of parameters. The theoretical results are found to be in very good agreement with the results obtained by simulation. Parameter variations show the extent of the parameter space where significant vibration cancelling can be achieved and illustrate possible applications.
Dynamically Stable Non-Linear Modes of Multiple Subharmonic Torsional Vibration Absorbers
Authors: Chao Chang-Po , Shaw Steven W. 
Published: February 2021

Abstract
Recent studies have demonstrated an arrangement of centrifugal pendulum vibration absorbers that is very effective at reducing torsional vibrations in rotating machinery. The basic system is composed of a pair of identical absorbers that are tuned to a one-half subharmonic order relative to the applied fluctuating torque. These absorbers, when moving in an out of phase manner along a particular path relative to the rotor, are capable of significantly reducing torsional vibrations of a desired order. In this paper we consider the response of systems composed of multiple pairs of these absorbers, with the goal of determining the dynamic stability of the desired response and the effects of small imperfections in the absorbers’ paths. The desired response of this system is one in which the N absorbers act as a single pair, with two groups of N/2 each moving with equal amplitude but exactly out of phase with respect to one another. It is shown that this response can be made to be dynamically stable and robust to certain model uncertainties by a slight, identical overtuning of each absorber. The analytical results, obtained by the method of averaging and symmetric bifurcation theory, are confirmed by simulations for the cases with two and three pairs of absorbers.
Dynamics of Friction Damped Braced Frames With Secondary Structures
Authors: Adam C. , Ziegler F. 
Published: February 2021

Abstract
The influence of light-weight secondary structures on the dynamic response of earthquake excited hysteretically damped shear frames with various elastic and inelastic substructure properties is studied numerically. The numerical procedure used in this paper is based on an iterative synthesis, where interface conditions as well as inelastic deformations are treated as additional fictitious loads and their intensities are updated in an iterative process. Acceleration response spectra of shear frames as well as floor response spectra are generated for various modal primary to secondary mass ratios. Also spectra of the standard deviation of primary and secondary accelerations are computed. Results, efficiently derived by the proposed method, are set in contrast to those derived by decoupled analyses to estimate their capability with respect to hysteretic structural behavior.
Distributed Jenkin Elements in Modeling Hysteresis in Cables
Authors: Hagedorn Peter , Gutzer Ulrich 
Published: February 2021

Abstract
In several previous papers the authors discussed the experimental determination and the mathematical modeling of hysteresis via the Masing model, in particular with view to the hysteresis in the transverse vibrations of cables (see [1–7]). In these papers, the authors focused on the energy dissipation in periodic (forced) or slowly decaying vibrations rather than an arbitrary, general motion. Locally in the cable, the relation between the bending momerts and the curvature was described by several Jenkin elements in addition to a constant bending stiffness term. Experimental data obtained in a simple test rig were then used to identify the parameters of the Jenkin elements.
The number of Jenkin elements in parallel used in the mathematical model depends on the design of the cable, i.e. on the number of layered strands. It can possibly be large in a complex steel cable. A different possibility to model the hysteresis in the case of many Jenkin elements, is to assume a continuous, distributed Masing model at each point of the cable. This corresponds to the assumption of an infinite number of layered strands, which of course is unrealistic in the physical system. Nevertheless, it may how ever lead to a good description of static hysteresis in certain systems. In addition, convenient assumptions on the distributed parameters of the Masing model may give rise to a well manageable identification problem. It then turns out that the hysteresis cycle can be conveniently described by a single initial loading function. In the present paper, it is shown how this function can be obtained from measurements carried out with the Darmstadt test rig, as also described in [5].
Study of Some Rheological Elastoplastic Models With a Finite Number of Degrees of Freedom
Authors: Bastien J. , Lamarque C. H. , Schatzman M. 
Published: February 2021

Abstract
A large number of rheological models can be covered by the existence and uniqueness theory for maximal monotone operators. Numerical simulations display hysteresis cycles when the forcing is periodic. A given shape of hysteresis cycle in an appropriate class of polygonal cycles can always be realized by adjusting the physical parameters of the rheological model.