bluuebunny/crossref_metadata_2025_split huggingface dataset:
Parametric Identification and Fault Detection in Vehicle Models With Nonlinear Suspension
Authors: Metallidis P. , Verros G. , Natsiavas S. , Papadimitriou C. 
Published: November 2020

Abstract
Systematic methodologies are applied for performing parametric identification and fault detection in nonlinear vehicle systems. The dynamic response of the vehicle models examined is caused by road excitation. In these models, the nonlinearities arise due to the function of the suspension dampers, which assume a different damping coefficient in tension and in compression. This leads to oscillator models with parameter discontinuities. First, emphasis is put on investigating some issues of fundamental importance, by employing a classical two degree of freedom quarter-car model. Since the dominant nonlinearities are due to switches between constant damping coefficients, appropriate methodologies are applied for obtaining exact motions of these models. Moreover, a statistically based methodology is applied for parametric identification and fault detection in vehicle suspensions with nonlinear characteristics, using dynamic test data. This methodology is then extended and applied to more involved and complete vehicle models. The numerical results presented demonstrate that this methodology provides an effective and practical way of detecting the type, location and severity of faults in vehicle suspensions.
Periodic Solutions of an Inhomogeneous Second Order Equation With Time-Dependent Damping Coefficient
Authors: Hartono  , van der Burgh A. H. P. 
Published: November 2020

Abstract
In this paper we will study the periodic solutions of an inhomogeneous second order equation with time-dependent damping coefficient:(1)x..+(c+ϵcos⁡2t)x.+(m2+α)x+Acos⁡ωt=0 where c, α, ϵ, A are small parameters and m, ω positive integers. Physically, the phenomenon of a time-dependent damping coefficient can occur in a special electrical circuit (RLC-circuit), or in a model equation for the study of rain-wind induced vibrations of a special oscillator. Because of the presence of a number of small parameters in equation (3) we will use the averaging method (up to third order) for the construction of approximations for the periodic solutions. The parameters c, α and A are considered to be small implying that they are expressed in the characteristic small parameter ϵ of the problem:(2)c=ϵc1+ϵ2c2+ϵ3c3,α=ϵα1+ϵ2α2+ϵ3α3,A=ϵA1+ϵ2A2+ϵ3A3, where ci, αi and Ai, i = 1, 2, 3 are of O(1).
For m, ω ∈ {1, 2, 3}, it will be shown that an O(1)-periodic solution exists if m = ω and if m ≠ ω the periodic solution is of order ϵ. Further, if c = O(ϵ), α = O(ϵ), and A = O(ϵ), for m = ω = 1 both stable and unstable periodic solutions exist but for m = ω = 2, 3 only stable periodic solutions are found. For the case that c = O(ϵ2), α = O(ϵ2), and A = O(ϵ2), for m = ω = 2, 3 only stable periodic solutions are found. But for m = 3 and α = (g/64)ϵ2 + O(ϵ3), c = O(ϵ3), A = O(ϵ3) both stable and unstable periodic solution exist. The stability of the periodic solutions follows from a new stability diagram related to equation (3) with A ≡ 0.
Generalized Harmonic Oscillators: Velocity Dependent Frequencies
Authors: Mickens Ronald E. 
Published: November 2020

Abstract
Preliminary results are given on a new class of nonlinear oscillator equations that generalize those of the usual linear harmonic case. These equations take the form ẋ = f(x)y and ẏ = −g(y)x, where f(x) and g(y) are continuous with first derivatives, and f(0) &gt; 0, g(0) &gt; 0. Of interest is the fact that these equations have a first-integral, i.e., there exists a function H(x,y) such that along a particular trajectory in the (x,y) phase space, H(x,y) = constant. We work out several general results related to this system of equations and illustrate them with several special cases that correspond to models of physical systems.
The work reported here was supported in part by research grants from DOE and the MBRS-SCORE Program at Clark Atlanta University.
Nonlinear Adaptive Vibration Absorber for the Control of Plate Vibrations
Authors: Ashour Osama N. , Nayfeh Ali H. 
Published: November 2020

Abstract
A nonlinear adaptive vibration absorber to control the vibrations of flexible structures is investigated. The absorber is based on the saturation phenomenon associated with dynamical systems possessing quadratic nonlinearities and a two-to-one internal resonance. The technique is implemented by coupling a second-order controller with the structure’s response through a sensor and an actuator. Energy is exchanged between the structure and the controller and, near resonance, the structure’s response saturates to a small value.
Experimental results are presented for the control of a rectangular plate and a cantilever beam using piezoelectric ceramics and magnetostrictive alloys as actuators. The control technique is implemented using a digital signal processing board and a modeling software.
The control strategy is made adaptive by incorporating an efficient frequency-measurement technique. This is validated by successfully testing the control strategy for a non-conventional problem, where nonlinear effects hinder the application of the nonadaptive controller.
Confinement and Suppression of Structural Vibrations
Authors: Choura Slim , Yigit Ahmet S. 
Published: November 2020

Abstract
A feedback strategy, aiming at confining and suppressing simultaneously the vibratory motion in flexible structures, is proposed. It is assumed that the structure consists of parts that are sensitive to vibration. The proposed strategy makes use of control inputs whose number is less than or equal to that of the dimension of the discretized model. The design objective is to devise a feedback scheme that leads to transferring the vibrational energy from the sensitive parts to the remaining parts of the structure. In order to keep away from the build-up of transferred energy in the nonsensitive parts, the feedback scheme considers, along with the confinement, the suppression of vibration in both the sensitive and non-sensitive parts. The proposed strategy also accounts for the presence of persistent excitations. A finite element model of a cantilever beam is used to show the viability of the proposed strategy.
Active Control of Radiated Sound From a Vibrating Plate
Authors: Hong Jin-Seok , Shin Kihong , Lee Choong-Hwi , Oh Jae-Eung 
Published: November 2020

Abstract
In this paper, an experimental study is described for active control of radiation sound from a vibrating plate under a harmonic excitation at a specific point. Two piezoceramic actuators are used to provide control inputs to the structure. The notion of control sensitivity of the plate bending moment is introduced to find the locations of piezoceramic actuators. Each piezoceramic actuator is located at the position that has the largest control sensitivity in order to maximize the control performance. The measurement sensors are two accelerometers whose outputs are processed through an array of linear filters. The impulse response of each filter is constructed from the vibro-acoustic path transfer function by accelerometers and microphones. The active structural acoustic control system is designed to estimate and reduce the radiated sound pressure on the basis of this transfer function. A 2 by 2 Filtered-x LMS algorithm is used, and is implemented on a TMS320C30 DSP board for the real-time control.
Nonlinear Behavior of Piezo-Beam-Systems Subjected to Weak Electric Field
Authors: von Wagner Utz , Hagedorn Peter , Nguyen Minh Nam 
Published: November 2020

Abstract
Experimental studies of piezo-beam systems subjected to weak harmonic electric fields have revealed typical nonlinear effects, e.g. dependence of the resonance frequency on the amplitude, superharmonics in spectra and a nonlinear relationship between excitation voltage and vibration amplitude. In contrast to the well-known nonlinear effects for piezoceramics in presence of strong electric fields, these effects have not been widely described in the literature.
In this paper we attempt a description of these phenomena by nonlinear constitutive relations, in particular by a non-constant elastic modulus Ec and piezoelectric factor d31. The equations of motion for the system under consideration are derived via the Ritz-method using Hamilton’s principle. The ‘nonlinear’ parameters are determined and the numerical results are compared to those obtained experimentally. The effects described herein may have a significant influence whenever structures are excited close to resonance frequencies via piezo-electric elements.
Shape Control of Timoshenko Beams by Shear-Based Piezoelectric Actuation
Authors: Krommer Michael , Irschik Hans 
Published: November 2020

Abstract
The present paper is concerned with the dynamic shape control of force loaded beams by means of the converse piezoelectric effect. We consider smart beams composed of substrate layers bonded to piezoelastic actuation layers with shaped electrodes at both sides. Piezoelastic extension actuators as well as piezoelastic shear actuators are used. We study transient disturbances produced by assigned forces, and we seek for a transient piezoelastic actuation which, when superimposed upon the assigned forces, leads to zero total displacements and cross-sectional rotations of the beams under consideration. In the following, a solution of this dynamic shape-control problem is presented which is exact within the framework of the Timoshenko theory of beams. The required shape-functions of the electrodes for eliminating the dynamic deformations due to the assigned forces are shown to be the quasi-static bending moment and shear force distributions due to the same assigned forces. When the assigned forces have a fixed space-wise distribution with a time-varying intensity, this solution can be easily realized and is felt to be appealing for practical purposes. We furthermore identify nilpotent shape functions, which may be added to the former solutions of the shape control problem without violating their validity.
A Comparative Study on Dynamic Wheel Loads of Multi-Axle Vehicle and Bridge Responses
Authors: Kim Chul Woo , Kawatani Mitsuo 
Published: November 2020

Abstract
To investigate relations between dynamic wheel loads of multi-axle vehicles on highway bridges and dynamic responses of bridge due to the vehicular loading, a three-dimensional dynamic analysis is carried out. Simultaneous differential equations for a coupling vibration of bridge and moving vehicle including roadway roughness are derived by means of modal analysis. The analytical wheel loads of vehicle model and responses of bridges are compared with experimental ones, to verify a validity of presented analytical procedure. Parametric investigations show that there exists resemblance between bounce motion of vehicle and bridge response. It can also be seen that the RMS based dynamic factor of dynamic wheel load can give an important information to predict the variation of impact factor of bridge due to speed condition as well as speed parameter.
Experimental Response of a Preloaded Vibro-Impacting Hertzian Contact
Authors: Rigaud Emmanuel , Perret-Liaudet Joël 
Published: November 2020

Abstract
This paper concerns the non-linear dynamic response of a vibro-impacting Hertzian contact. Sinusoidal and random external normal forces are considered. We focus on the primary resonance and include vibro-impact responses in order to analyze the main characteristics of the system associated to both Hertzian and contact loss non-linearities. Under very small input amplitude, contact exhibits an almost linear resonance. Linearized resonance frequency and damping ratio are identified. Increasing the external input amplitude, the softening behaviour induced by Hertzian nonlinear stiffness is clearly demonstrated for both sinusoidal and random inputs. For higher input amplitude, system exhibits vibro-impacts. The contact loss non-linearity strongly governs the dynamic behaviour of the system.
Measurement and Analysis of Modulated Doublet Mode Response in Mock Bladed Disks
Authors: Chang J. Y. , Wickert J. A. 
Published: November 2020

Abstract
The steady-state response of spatially modulated doublet modes that occur in low count flexible bladed disks is investigated for the case in which the structure is driven by a harmonic traveling wave excitation source. Finite element simulation and modal testing of prototypical bladed disk structures demonstrate the presence of particular wavenumbers, beyond the base number of nodal diameters, which contaminate and distort the appearance of certain doublet modes. The manner in which the natural frequency and wavenumber content of such modes shift and split as functions of the number of blades and their span angle is discussed in the light of a companion perturbation analysis for rotationally periodic structures. Resonance conditions are established and verified through simultaneous measurements made with a spin test stand using sensors that are placed in the rotating (structure) and stationary (excitation) frames of reference. The traveling wave response components of a repeated frequency doublet mode are shown to propagate either in the same or opposite direction as the excitation source, depending on whether certain algebraic relationships between the excitation order, the base number of nodal diameters, and the contamination wavenumbers are satisfied. To the extent that such components can travel at different phase speeds and directions relative to one another, the placement of sensors on the structure can be optimized to best measure the response amplitude. Conversely, other placements can result in sub-maximal measurement of peak vibration amplitude over the structure.
Stability of Interrupted Cutting by Temporal Finite Element Analysis
Authors: Bayly P. V. , Halley J. E. , Mann B. P. , Davies M. A. 
Published: November 2020

Abstract
Chatter in milling and other interrupted cutting operations occurs at different combinations of speed and depth of cut from chatter in continuous cutting. Prediction of stability in interrupted cutting is complicated by two facts: (1) the equation of motion when cutting is not the same as the equation when the tool is free; (2) no exact analytical solution is known when the tool is in the cut. These problems are overcome by matching the free response with an approximate solution that is valid while the tool is cutting. This approximate solution is obtained by the application of finite elements in time. The complete, combined solution is cast in the form of a discrete map that relates position and velocity at the beginning and end of each element to the corresponding values one period earlier. The eigenvalues of the linearized map are used to determine stability. Predictions of stability are confirmed by experiment.
Nonlinear Dynamics of the Woodpecker Toy
Authors: Leine Remco I. , Glocker Christoph , van Campen Dick H. 
Published: November 2020

Abstract
This paper studies bifurcations in systems with impact and friction, modeled with a rigid multibody approach. Knowledge from the field of Nonlinear Dynamics is therefore combined with theory from the field of Nonsmooth Mechanics. The nonlinear dynamics is studied of a commercial wooden toy. The toy shows complex dynamical behaviour but can be studied with a one-dimensional map, which allows for a thorough analysis of the bifurcations.
Chaotic Motion in the Vicinity of Separatrix of a Parametrically Driven Duffing Oscillator With a Twin-Well Potential
Authors: Luo Albert C. J. 
Published: November 2020

Abstract
The conditions for the (M:1) and (2M:1) resonances inside and outside of the separatrix of the parametrically driven Duffing oscillator are determined. The onset of such resonance in the vicinity of separatrix is investigated analytically and numerically. The results presented in this article can be applied to the post-buckled structures under parametric excitations.
New Approach of Wavelet Fractal Analysis to Mechanical Fault Diagnosis
Authors: He Zhengjia , Zi Yanyang , Chen Peng , Toyota Toshio 
Published: November 2020

Abstract
Wavelet transform decomposes signals in both time and frequency domains. According to the principle of multi-resolution, irregularities or complexities of decomposed signals in various frequency bands are different, which can indicate mechanical fault. Fractal dimension of decomposed signal is an excellent factor to express the irregularity or complexity. It can make features of mechanical faults remarkable. Based on wavelet fractal dimension, successful diagnosis of looseness fault of bearing bridge for 50MW turbo-generator was obtained.
Can Wavelet Transforms Used for Data Compression Equally Suitable for the Use of Machine Fault Diagnosis?
Authors: Tse Peter W. , He Ling S. 
Published: November 2020

Abstract
Wavelet transforms are capable of separating the raw vibro-acoustic signals into different frequency and time bands. They have exhibited potentials in the detection of fault related impulsive signals by using their multi-resolution time-frequency analyses. To ensure the design of wavelet transforms is simple and the processing is not time intensive, discrete type of wavelet transforms (DWTs) become popular as they are composed of low-pass and high-pass digital filters only, making them easier to implement and processing faster. Recently, a number of publications have applied the similar type of DWTs commonly used for data compression (dyadic type of DWTs) in vibration based machine fault diagnosis. However, the results are not satisfactory. The main reasons are the poor resolution provided by DWTs and the inappropriate design of digital filters causing undesirable frequency aliasings. Without taking care of these problems, they may lead to false alarms in fault diagnosis. In this paper, we present a new family of DWTs, which mainly consists of a series of Butterworth filter banks. They are capable of providing sufficient resolutions in different time and frequency ranges, and minimizing the effect of frequency aliasing. The results have shown that the new types of DWTs are promising in solving the problems and tailor-made for machine fault diagnosis. With the help of the new DWTs, the faults that exhibit non-linear and non-stationary signals can be detected easier and the diagnosis becomes more reliable.
Web and Virtual Instrument Based Machine Remote Sensing, Monitoring and Fault Diagnostic System
Authors: Tse Peter W. , He Ling S. 
Published: November 2020

Abstract
Failure of equipment not only leads to loss of production, but also, in some serious situations, causes human casualty. Hence, the need of equipment condition monitoring becomes crucial for reliable operations. Since expensive hardware instruments are needed for condition monitoring, with the current powerful PCs, software based virtual instruments are possible to replace hardware instruments. However, the software must be maintained for each PC, and a technician must still visit the site of the PC and its monitored equipment. By connecting the PC to the Internet, remote sensing and equipment fault diagnosing are possible. As only one copy of software for each type of virtual instrument is required on the server, the maintenance of virtual instrument is much easier and substantial cost of hardware instruments is reduced. Moreover, remote collaborative maintenance becomes feasible as worldwide experts can provide just-in-time advice to technicians via the Web. With the new standards of IEEE 1451.2 for smart transducers, the new sensors are self-Web-ready. Sensor manufacturers, such as Hewlett Packard and Bruel & Kjaer, have proclaimed their next generation sensors are self-Web-ready. Therefore, the development of a Web-based maintenance is a must in the near future. This paper presents the design and development of a solution and a platform for the Web-based remote collaborative diagnosis and maintenance. It consists of remote data sensing and logging, signal analysis using virtual instruments, and intelligent fault diagnosis and prognosis.
Reducing Friction Forces by Means of Applied Vibration
Authors: Bucher Izhak , Wertheim Oded 
Published: November 2020

Abstract
It has been observed that inducing vibration into structures can reduce the friction force between two sliding objects. This phenomenon has been used in positioning systems and recently was investigated in relation to various machining processes. The present paper brings an experimental work where a wide range of vibrating patterns is introduced to a surface on which a rigid mass is forced to slide. It has been observed that the dynamics of the involved mechanical components has an important role in the determination of the friction force. Structural optimization has been used to efficiently convey a large amount of energy to the mechanical surface to a degree that a combination of a squeeze film and the enlargement of the mean gap between the sliding surfaces reduce the friction force by orders of magnitude. Explanation of the involved physical phenomena alongside with experimental evidence will be presented to support the proposed theory.
Sensorless Early Detection of Mechanical Faults: Developments in Smart Rotating Machines
Authors: Parlos Alexander G. , Kim Kyusung , Bharadwaj Raj M. 
Published: November 2020

Abstract
Practical early fault detection and diagnosis systems must exhibit high level of detection accuracy and while exhibiting acceptably low false alarm rates. Such designs must have applicability to a large class of machines, require installation of no additional sensors, and require minimal detailed information regarding the specific machine design. Electromechanical systems, such as electric motors driving dynamic loads like pumps and compressors, often develop incipient failures that result in downtime. There is a large number of such failure modes, with a large majority being of mechanical nature. The precise signatures of these failure modes depend on numerous machine-specific factors, including variations in the electric power supply and driven load. In this paper the development and experimental demonstration of a sensorless, detection and diagnosis system is presented for incipient machine faults. The developed fault detection and diagnosis system uses recent developments in dynamic recurrent neural networks in implementing an empirical model-based approach, and multi-resolution signal processing for extracting fault information from transient signals. The signals used by the system are only the multi-phase motor current and voltage sensors, whereas the transient mechanical speed is estimated from these measurements using a recently developed speed filter. The effectiveness of the fault diagnosis system is demonstrated by detecting stator, rotor and bearing failures at early stages of development and during different levels of deterioration. Experimental test results from small machines, 2.2 kW, and large machines, 373 kW and 597 kW, are presented demonstrating the effectiveness of the proposed approach. Furthermore, the ability of the diagnosis system to discriminate between false alarms and actual incipient failure conditions is demonstrated.