bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comparison of Bending Models of Multiwire Strand
Authors: Jayakumar C. V. , Sathikh S. , Jebaraj C. 
Published: February 2021

Abstract
Nine discrete thin rod models are critically compared for their merit for studying the bending response of strands. Four bench marks employed for comparison are two (upper and lower) bounds of bending stiffness and two strand curvatures at slip initiation and completion. The strand configuration chosen, the way in which the lay angle is employed to describe the effective area of cross section as well as moments of inertia of the wire and the components of forces; the inclusion or omission of the wire interaction with the core through friction contact and the moment of inertia of the wire about its own diameter; and of wire couples in part or full are identified as factors that make the difference. Numerical values of the four bench marks for these models are presented.
Nonconservative Stability of a Friction Loaded Disk
Authors: Tseng Jung-Ge , Wickert Jonathan A. 
Published: February 2021

Abstract
This paper investigates the vibration of an annular disk that is subjected to rotation and in-plane frictional traction distributed over a sector of the disk’s two faces. Technical applications include noise, vibration, and harshness in automotive and aircraft disk brakes, and other rotating machine components. To the degree that the rotor-to-stator friction in such cases is directed along the disk’s deformable surface, it is treated here as a nonconservative follower-type load. The vibration model incorporates membrane stiffness which derives from rotation and the stresses established as a result of friction. The plane stress state is determined in closed form as a Fourier series, and that solution is compared with the companion, but computationally intensive, results from finite element analysis. For the cases of sector-shaped and full annular loading, the vibration model predicts the critical mode, which is defined as the one that becomes dynamically unstable at the lowest friction level. Vibration modes that fall into opposite symmetry classes, both with and without rotation, also have opposite stability-characteristics in the presence of frictional loading.
Design and Control of Shipboard Cranes
Authors: Yuan Guo Hui , Hunt Brian R. , Grebogi Celso , Ott Edward , Yorke James A. , Kostelich Eric J. 
Published: February 2021

Abstract
We propose a new cable rigging for a ship crane in order to control load pendulation. The “Maryland Rigging” involves the addition of a pulley-brake mechanism to the existing configuration. We show numerically that by applying friction in this rigging system we are able to reduce pendulation enormously.
Forced Oscillations of a Continuous Rotor With Geometric Nonlinearity: Internal Resonance Phenomena at Harmonic and Subharmonic Resonances
Authors: Ishida Yukio , Nagasaka Imao , Lee Seongwoo 
Published: February 2021

Abstract
Harmonic resonances and subharmonic resonances of order 1/2 and order 1/3 in a continuous rotating shaft with distributed mass are discussed. The restoring force of the shaft has geometric stiffening nonlinearity due to the extension of the shaft center line. It is supposed that a distributed bias force, such as the gravity, works. The possibility of their occurrences, the shapes of resonance curves, and internal resonance phenomena are investigated.
Some Interesting Characteristics of a Simple Autonomous Impact System With Symmetric Clearance
Authors: Mattos M. C. , Weber H. I. 
Published: February 2021

Abstract
The study of impact systems is gaining increased interest due to many practical situations where impact affects the overall dynamics. However, there are few results in the literature leading to a clear understanding about how the dynamics of MDOF systems with impacts changes, as several parameters are altered. In this work we investigate changes in the response of a 2-DOF impact system with symmetric clearance as the clearance is varied. The analyzed system is autonomous, so that the changes in its response are related only to the alteration in its “self dynamics”. As a second goal we investigate the occurrence or not of the migration of characteristic frequencies1 such as it was observed by Piccoli (1994) in a rotor with clearance and impact in one of its bearings.
Post-Critical Dynamics of an Axially Moving Beam
Authors: Vestroni Fabrizio , Pellicano Francesco 
Published: February 2021

Abstract
In the present paper, the dynamic behaviour of a beam subjected to an axial transport of mass is analyzed. The Galerkin method has been used to discretize the problem; a high dimensional system of ordinary differential equations with linear gyroscopic part and cubic nonlinearities is obtained. The system is studied in the sub and supercritical speed ranges with emphasis on 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 linear subcritical behaviour, static bifurcation analysis including linear stability and direct simulation of global postcritical dynamics.
Identification of a Two Degree of Freedom Experimental System Using a Force Appropriation Approach
Authors: Atkins P. A. , Wright J. R. 
Published: February 2021

Abstract
The identification of nonlinear multi degree of freedom systems involves a significant number of nonlinear cross coupling terms, whether the identification is carried out in spatial or modal domains. One possible approach to reducing the order of each identification required is to use a suitable pattern of forces to drive any mode of interest. For a linear system, the force pattern required to drive a single mode is derived using a Force Appropriation method. This paper presents a method for determining the force pattern necessary to drive a mode of interest of a nonlinear system into the nonlinear region whilst the response is controlled to remain in proportion to the linear mode shape. Such an approach then allows the direct nonlinear modal terms for that mode to be identified using the Restoring Force method.
The method for determining the relevant force patterns is discussed. The implementation of the method for experimental systems is considered and experimental results from a two degree of freedom ‘benchmark structure’ are presented. Two methods of estimating the mass for a restoring force identification are compared.
Active Isolation Design for a Flexible Base
Authors: Sciulli Dino , Inman Daniel J. 
Published: February 2021

Abstract
It has been commonly assumed that the corner or mount frequency in an isolator should be designed as low as possible. This is one result of using a single-degree-of-freedom (SDOF) system to model isolation systems. However, for systems that have flexible or nonrigid foundations, a design point for the mount frequency can occur between the modes of the base. By implementing this type of design, a strong interaction will exist between the modes. When isolator damping is included, whether done passively or actively, more than one mode can be attenuated for this new mount design. Therefore, the effects of the mount frequency on isolation designs are discussed as well as using both passive and active damping in the isolator. For active damping, three commonly used control methodologies are discussed: a proportional-plus-integral-plus-derivative (PID) controller, a positive position feedback (PPF) controller, and a linear quadratic Gaussian (LQG) regulator.
Semiactive Control of Multiple Degree of Freedom Systems
Authors: Ahmadian Mehdi 
Published: February 2021

Abstract
Semiactive control of systems with multiple degrees of freedom is addressed. Two systems representing a pitch-plane model of a vehicle and a single suspension are used to illustrate the results. The dynamic simulations show the well-known compromise between resonance control and isolation, due to passive dampers. It is shown that semiactive dampers also compromise between controlling different bodies. For skyhook and groundhook control policies, the control of one body is achieved at the cost of less control on the other bodies. For instance, in a single suspension model, skyhook semiactive dampers better control the body resonance, but significantly increase the axle resonance (wheelhop). The groundhook dampers provide a better control of wheelhop at the expense of increasing body resonance. A hybrid control policy that combines the effect of skyhook and groundhook policies is introduced. This policy can be used to provide the proper control on all bodies, while using the hardware common to existing semiactive dampers.
Dynamics of CVT Chain Drives: Mechanichal Model and Verification
Authors: Srnik Jürgen , Pfeiffer Friedrich 
Published: February 2021

Abstract
This paper deals with the dynamics of continuously variable (CVT) chain drives. According to the discrete structure of the chain, which causes the polygonal actions, the mechanical model contains each chain link and pulley as a separate body. While a chain link is part of a strand, only joint forces including friction act on the chain links, whereas in the contact situation additional impulsive and frictional forces in the contact zones between the chain link’s rocker pins and the tapered surfaces of the cone pulleys have to be taken into account. For the calculation of the contact forces Coulomb’s friction law as well as a time sparing continuous approximation are applied.
Simulation results show the influence of the cone pulley’s deformation on the power transmission. They also show the repercussion of the polygonal action. Furthermore the chain’s pitch influence on the vibrational behavior of the transmission is discussed. A comparison of calculated and measured tensional forces verifies the model presented.
Wavelet Novelty Measure for Machinery Diagnostics
Authors: Staszewski Wiesław J. 
Published: February 2021

Abstract
The paper is concerned with wavelet analysis for fault detection in machinery diagnostics. A new approach based on novelty detection is presented. The method involves a wavelet compression algorithm to vibration data in order to extract a set of features which are related to the fault. The compression algorithm uses orthogonal Daubechies’ wavelets and a simple thresholding procedure. The wavelet based novelty measure is established as a statistical distance between decoded data representing different fault advancements.
Simultaneous Stiffness and Mass Change Detection Based on Reduced Measurements
Authors: Baruch Menahem 
Published: February 2021

Abstract
Simultaneous changes in the stiffness and mass matrices of a dynamic structure can be detected by using reduced measurements. In the method proposed here, both, the stiffness and the mass matrices, are assumed to be incorrect. The missing measurements can be calculated by utilizing the connection between the measured and unmeasured quantities trough the iterative process of identification of the tested structure. The missing measurements and to some extend the partial measurements obtained during the tests are treated as hidden functions of the parameters of the structure. This makes the Euclidean norm of the appropriate matrix to be minimized a nonlinear function of the parameters. This norm may have more than one minimum. The changes in the stiffness and mass matrices must be identified by looking for the global minimum of the Euclidean norm. The global minimum can be found by changing the initial values of the parameters or by changing some special coefficients, or both. A discussion of the minimal number of necessary measurements in connection with the number of the parameters of the stricture is included.
In order to identify the stiffness and mass parameters of the structure the measured and the supplied missing quantities are forced to comply with the general laws for a linear structure. This compliance is achieved during any step of the iterative process.
The structure is idealized to be a linear dynamic structure without damping. The reduced measured quantities are measured during the tests at discrete points of the Frequency Response Function.
Updating of Impact Models for Vibrating Cantilever Beams
Authors: Szwedowicz Dariusz , Sotelo Carlos A. 
Published: February 2021

Abstract
In the paper, the numerical technique for simulations of impact problems of stationary vibrating beams is proposed. Good qualitative agreements between the computed and measured impact forces and contact duration are obtained. For getting better quantitative agreements between the measurements and simulations, some improvements of the experimental set-up are discussed.
Updating Rotor-Bearing Finite Element Models
Authors: Mares Cristinel , Surace Cecilia 
Published: February 2021

Abstract
In this paper, the possibility of updating the finite element model of a rotor-bearing system by estimating the bearing stiffness and damping coefficients from a few measured Frequency Response Functions using a Genetic Algorithm is investigated. The issues of identifiability and parameters estimation errors, computational costs and algorithm tuning are addressed. A simulated example of a flexible rotor supported by orthotropic bearings is used for illustrating the method.
Damage Detection Based on Vibration Measurements and Inaccurate Models
Authors: Fritzen C.-P. , Jennewein D. , Kiefer Th. 
Published: February 2021

Abstract
The paper presents a model-based approach for the detection of structural damage with respect to location and extent from measured vibration test data. The method which is tolerant to small modeling errors is based upon an analytically redundant mathematical model approximately representing the undamaged structure.
The motivation was that in many practical cases it is not possible to obtain perfect correlation between the undamaged system and the original model due to modeling uncertainties or excessive modeling cost.
On the other hand, in the early phase of damage evolution the changes of the dynamical characteristics are very small. If the changes due to the damage are superimposed by the effects of mismodeling it is nearly impossible to get reliable diagnostic results. Therefore, an approach is presented here for the case that a perfect model cannot be obtained.
The resulting inverse problem usually is ill-posed, so that special attention must be paid to its accurate numerical solution. The application to damage detection problems requires the reduction of a large set of damage parameter candidates to a small subset of one or two parameters really describing the local change of the system. An orthogonalization strategy is given to reduce the parameter set and Akaike’s information criterion is used to confirm the correct size of the parametrization.
The method is applied to two laboratory structures: a multi-story frame and a damaged plate. The results show that the algorithm is able to localize and quantify the damage also in the presence of modeling errors.
The Application of Probability Theory to Model Updating
Authors: Papadopoulos Loukas , Garcia Ephrahim 
Published: February 2021

Abstract
A method is proposed for probabilistically model updating an initial deterministic finite element model using measured statistical changes in natural frequencies and mode shapes (i.e., modal parameters). The approach accounts for variations in the modal properties of a structure (due to experimental errors in the test procedure). A perturbation of the eigenvalue problem is performed to yield the relationship between the changes in eigenvalues and in the global stiffness matrix. This stiffness change is represented as a sum over every structural member by a product of a stiffness reduction factor and a stiffness submatrix. Monte Carlo simulations, in conjunction with the variations of the structural modal parameters, are used to determine the variations of the stiffness reduction factors. These values will subsequently be used to estimate statistics for the corrected stiffness parameters. The effectiveness of the proposed technique is illustrated using simulated data on an aluminum cantilever Euler-Bernoulli beam.
Thermally Induced Synchronous Instability of a Radial Inflow Overhung Turbine: Part II
Authors: Faulkner H. B. , Strong W. F. , Kirk R. G. 
Published: February 2021

Abstract
This paper is in two parts, and concerns the lateral dynamics of a large turbocharger rotor with overhung wheels. Initial rotor dynamic analysis indicated no excessive motion in the operating speed range. However, testing showed excessive motion, which was initially traced to the radial-inflow turbine wheel becoming loose on the shaft, due to transient differential thermal expansion in the wheel on startup. The attachment of the wheel was modified to eliminate this problem. The discussion up to this point is in Part I of the paper, and the remainder is in Part II. The wheel attachment modification extended the range of satisfactory operation upward considerably, but excessive lateral motion was again encountered near the upper end of the operating speed range. This behavior was traced to thermal bowing of the shaft at the turbine end, known as the Morton Effect. The turbine end bearing was modified to eliminate this problem, and satisfactory operation was then achieved throughout the operating speed range.
Critical Speeds of Shaft-Disk Systems Subjected to Longitudinal Forces
Authors: Chen Lien-Wen , Sheu Hong-Cheng 
Published: February 2021

Abstract
The critical speeds of a spinning Timoshenko shaft with an intermediate attached disk subjected to a longitudinal force are analytically solved. The expressions of whirl speed equations for hinged-hinged, hinged-clamped, clamped-hinged, and clamped-clamped rotors are given respectively. The critical speeds of each shaft-disk system are sought from its corresponding whirl speed equation by using simple numerical techniques. The effects of the disk location and the longitudinal force on the critical speeds of the shaft-disk systems are investigated. Numerical results reveal that if the disk locates in the left portion of the shaft, both the primary forward and backward critical speeds for the rotor subjected to a follower force are larger than those subjected to an axial force with the same magnitude. The results are contrary while the disk locates in the right portion of the shaft.
Nonlinear Dynamic Performance Analysis of Elastic Linkage Mechanisms
Authors: Xianmin Zhang , Xuemei Guo 
Published: February 2021

Abstract
In this paper, the generalized nonlinear equations of motion for elastic linkage mechanism systems are presented, in which the gross motion and elastic deformation coupling terms and the geometric nonlinearity effects are taken into account. The equations of motion are period and time-varying nonlinear equations. According to the characteristics, solution method for this kind nonlinear equations is investigated, and an efficient closed-form iterative procedure is presented. The effects of geometric nonlinearity on linkage mechanisms are studied. The results of this study are important for dynamic design of linkage mechanism systems.
Impact Analysis of Flexible Multi-Armed Terrestrial Robots
Authors: Bakr E. M. 
Published: February 2021

Abstract
A nonlinear formulation for the dynamic analysis of a flexible multi-armed terrestrial robot system which is subjected to a sudden collision during its functional use is presented. Finite rotations and large deformations of the arms are accounted for by using a Timoshenko beam theory of flexural vibration. Impacts and associated impulsive forces are incorporated into the formulation using a generalized impulse momentum balance. Numerical experimentations indicate that the use of a geometrically nonlinear Timoshenko beam model that can undergo large reference rotations could have a significant effect on the transient response of multi-armed robots subjected to impact loading.
Recovery of Joint Reaction Force for Real-Time Recursive Multibody Dynamics
Authors: Tsai Fuh-Feng , Mirtaheri Masoud 
Published: February 2021

Abstract
This paper proposes a formulation and parallel algorithm for the computation of all joint reaction forces in the recursive multibody dynamics. First, the Lagrange Multipliers associated with cut joints in each decoupled loop of a mechanical system are recovered. Then the joint reaction forces for the cut joints are computed directly using the obtained Lagrange Multipliers. After that, joint reaction forces associated with uncut joints are computed in backward computational paths, using synchronization in all junction nodes. A parallel algorithm for recovering reaction forces and torques for all cut joints and uncut joints is proposed. For validation, a space slider 3-D model is illustrated to compare the simulation results with those obtained from a commercial code DADS. Finally, A passenger car 14-body model is generated and simulated to obtain the joint reaction forces for the purpose of vehicle component design purpose.
Fault Identification for Rotating Machinery Using Adaptive Signal Processing and Time-Frequency Analysis
Authors: Lee Sang-Kwon , White Paul R. 
Published: February 2021

Abstract
Impulsive sound and vibration signals in rotating machinery are often associated with faults which lead to due to irregular impacting. Thus these impulsive sound and vibration signals can be used as indicators of machinery faults. However it is often difficult to make objective measurement of impulsive signals because of background noise signals. In order to ease the measurement of impulsive sounds embedded in background noise, we enhance the impulsive signals using adaptive signal processing and then analyze them in time and frequency domain by using time-frequency representation. This technique is applied to the diagnosis of faults within internal combustion engine and industrial gear.
Analysis of Dynamic Stress Responses in Structural Vibration
Authors: Huang Liping 
Published: February 2021

Abstract
This paper describes basic concepts and finite element method of dynamic stress response analysis. It provides basics of stress modal analysis and frequency response analysis. The paper defines concepts of normal mode stresses and complex stress frequency response functions for shell elements and shows that element stress responses in both time and frequency domains can be expressed as superposition of normal mode stresses. It demonstrates that element stress response solutions have the similar forms to those of node displacement responses and that normal mode stresses in stress analysis play the same role as mode shapes in normal vibration analysis.
Identification of Viscoelastic Properties of Finite Element Structures With Joints
Authors: Herrmann Torsten , Chaika Valdas 
Published: February 2021

Abstract
Identification of the damping and stiffness parameters of the composite joints in finite element structures is analyzed. For the modeling of the viscoelastic properties of the joints the classical Voigt-Kelvin and generalized Maxwell model (three parameter solid) are used. A time domain identification algorithm for classically and non-classically damped dynamic systems is developed. It is based on the application of an extended Kalman filter and least square technique. The algorithm uses complex modal analysis and sparse matrix technology. Both force and base excited systems are considered. Experimental verification of the identification results is carried out on a test structure. The accuracy of the modeling of damping in the joint using the Voigt-Kelvin and generalized Maxwell models is investigated.