bluuebunny/crossref_metadata_2025_split huggingface dataset:
Harmonic Analysis of Semiactive Suspensions
Authors: Ahmadian Mehdi , Reichert Brian A. , Song Xubin 
Published: February 2021

Abstract
This paper studies the behavior of semiactive suspensions subjected to a pure-tone input. A base-excited system, representing a single suspension, is used to compare the vibration isolation due to a conventional passive damper, an optimal passive damper, and two different types of semiactive dampers. The semiactive dampers considered are on-off (bang-bang) and continuously-variable semiactive dampers. Similar to the optimal suspension, both on-off and continuously-variable semiactive suspensions exhibited the ability to lower the resonance peak without worsening the isolation at higher frequencies. The results further show that semiactive dampers can be useful for a variety of applications including sensitive machinery that cannot tolerate any overshoot in power-up or power-down, and yet must have good isolation during normal operation.
Self-Motion Utilization for Reducing Vibration of a Structurally Flexible Redundant Robot Manipulator System
Authors: Kim Seon-Jae , Park Youn-Sik 
Published: February 2021

Abstract
This paper addresses the self-motion utilization of structurally flexible redundant manipulators to reduce the vibration of links when structural flexibility is present. Utilizing the self-motion capability, the motion-induced vibration can be further reduced by altering the joint trajectory during and after motion, while maintaining the end-effector tracing a given trajectory. That is because self-motion does not affect end-effector motion at all. In this proposed algorithm, a null space acceleration is evaluated in order to cancel the inertia force of flexural motion that is induced by its rigid body motion. A concept of modal space is applied to reduce the system degree of freedom. The dominant modal forces defined at a specific time, which are the same number of degree of redundancy can be effectively canceled out by employing self-motion. Through numerical simulation with three-link planar robotic manipulators, the effectiveness and applicability of the suggested method have been demonstrated.
Wavelet Based Edge Detection for Structural Dynamics
Authors: Patsias Sophoclis , Staszewski Wieslaw J. , Tomlinson Geoffrey R. 
Published: February 2021

Abstract
A new approach to dynamic testing/analysis based on the use of video data and edge contours is presented. Structural vibration is captured by the use of a computer video camera and wavelet analysis is then applied to each video frame. The analysis employs the discrete dyadic wavelet transform and the Mallat edge detection algorithm. The method is applied to the vibration analysis of a cantilever beam with a fault.
Motion Detection for a Precision Positioning System by Wavelet Analysis
Authors: Tai Hung-Ming , Sung Cheng-Kuo 
Published: February 2021

Abstract
The defects due to wear or improper assembly processes may induce undesirable vibrations that in turn cause mechanical failures. This paper employs Wavelet Transform to analyze the vibration of the pitch motion of the carriage in a precision positioning system. Two accelerometers are attached to the carriage at different locations and the accelerations are used to investigate the vibration of the pitch motion. By using Wavelet Transform, the signal measured from the proposed experimental setup are appropriately processed and used for the diagnosis of the defects. The percentage of the band energy (PBE)is found to be a helpful reference for detecting the abnormal conditions. This method successfully combines the techniques of measurement with the theory of the wavelet analysis in monitoring a precision positioning system. The difference between the results obtained both from the Short-Time Fourier analysis and wavelet analysis is also discussed.
Reliable Mode Shape Expansion Method for Error Localisation and Model Updating
Authors: Collignon Philippe , Golinval Jean-Claude 
Published: February 2021

Abstract
Failure detection and model updating using structural model are based on the comparison of an appropriate indicator of the discrepancy between experimental and analytical results. The reliability of the expansion of measured mode shapes is very important for the process of error localization and model updating.
Two mode shape expansion techniques are examined in this paper : the well known dynamic expansion (DE) method and a method based on the minimisation of errors on constitutive equations (MECE). A new expansion method based on some improvements of the previous techniques is proposed to obtain results that are more reliable for error localisation and for model updating.
The relative performance of the different expansion methods is demonstrated on the example of a cantilever beam.
Combining Subset Selection and Parameter Constraints in Model Updating
Authors: Friswell M. I. , Mottershead J. E. , Ahmadian H. 
Published: February 2021

Abstract
Model updating often produces sets of equations whose solution are ill conditioned and extra information must be used to produce a well conditioned estimation problem. One possible solution is to use regularisation, where all the possible parameters are changed, but extra constraints are introduced. This paper takes a different approach, by considering only a subset of the parameters to be in error. The critical decision is then the choice of parameters to include in the subset. The methods of subset selection are outlined and extended to the selection of groups of parameters. The incorporation of side constraints is considered and demonstrated using an experimental example.
The Influence of Experimental Errors on the Correction Parameters of Finite Element Models
Authors: Keye Stefan 
Published: February 2021

Abstract
A simulation study has been performed on the influence of experimental errors on the accuracy of finite element model corrections. The impact of measurement uncertainties on the sub-structure correction factors, natural frequencies, and mode shape correlation is investigated using simulated modal data. Different numerical models are used to assess the effects of modelization error magnitudes and locations.
Generalized Reference Basis Model Updating in Structural Dynamics
Authors: Kenigsbuch Rachel , Halevi Yoram 
Published: February 2021

Abstract
The paper considers the problem of updating an analytical model from experimental data. The approach that is taken is the reference basis, where some of the parameters are considered to be completely accurate while the others are updated by solving a constrained optimization problem. The main results of this paper are closed form solutions to these problems with general weighting matrices in the optimization criterion. These are generalizations of several model reference updating problems that were solved and reported in the literature. The importance of this generalization is the ability to incorporate prior knowledge regarding the accuracy of the model in specified areas into the method.
Another aspect of this work is the investigation of geometrical interpretation of the results which provides insight into the mechanism of the updating process. The advantages of the new updating schemes are demonstrated by means of examples.
Realization of Controllers for DC and Vector Controlled Induction Motors
Authors: Ismail Farouk , Khashab Hisham El , Mahgoub Osama , Oshiba Ahmed 
Published: February 2021

Abstract
Controller constants play an important role in electric drive system dynamics. The vector control permits to consider the induction motor as an equivalent separately excited DC machine, as a result, the dynamics of the two machines are compared. Experimental realization and computer simulation are constructed under PI and PID controllers.
A sensitivity study for the controllers constants and for the machines time constant is carried out and demonstrated for both machines under the same conditions. The computer simulation of the electric drive systems is constructed using the MATLAB-SIMULINK software package.
A Comprehensive Torsional Vibration Analysis Procedure: Part II
Authors: Corbo Mark A. , Malanoski Stanley B. 
Published: February 2021

Abstract
This is the second of two papers that provide users with a practical design procedure to ensure that their turbomachinery drive trains will not experience any torsional vibration problems in the field. In Part I, a procedure was given for determining the system’s governing interference points. Accordingly, this part focuses on the steps needed to determine the drive train’s ability to withstand these interference points.
Wave Propagation Analysis of an Axially Strained, Rotating Timoshenko Shaft: Part II
Authors: Kang Bongsu , Tan Chin An 
Published: February 2021

Abstract
In this paper, the wave reflection and transmission characteristics of an axially strained, rotating Timoshenko shaft under general support and boundary conditions, and with geometric discontinuities are examined. As a continuation to Part I of this paper (Kang and Tan, 1997), the wave reflection and transmission at point supports with finite translational and rotational constraints are further discussed. The reflection and transmission matrices for incident waves upon general supports and geometric discontinuities are derived. These matrices are combined, with the aid of the transfer matrix method, to provide a concise and systematic approach for the free vibration analysis of multi-span rotating shafts with general boundary conditions. Results on the wave reflection and transmission coefficients are presented for both the Timoshenko and the Euler-Bernoulli models to investigate the effects of the axial strain, shaft rotation speed, shear and rotary inertia.
Evaluation of Simplifying Assumptions in the Dynamics of Tethered Systems
Authors: Pasca Monica 
Published: February 2021

Abstract
Different simplifying assumptions can be formulated for the analysis of tethered systems, each of them with its own degree of fidelity and range of validity. The present paper points out the meaning of linear gravity gradient approximation for long tethers, constant tension along them and rigid deviation from the local vertical of a tethered system subjected to aerodynamic drag. A simplified model is presented and compared with numerical integration of the comprehensive nonlinear equilibrium equations. Numerical simulations refer to a probe to be flown in Martian atmosphere.
Prediction of Coupled Vibrations in Hard Disk Drive Spindle Systems
Authors: Lee Chong-Won , Jia Huan-Suo , Seo Jeong-Hwan , Kim Cheol-Soon , Chun Sang-Bok 
Published: February 2021

Abstract
A commercial hard disk drive spindle system is modeled as a flexible shaft with multiple flexible disks, which is supported by bearings, and its complicated coupled vibration characteristics are analyzed by using a substructure synthesis technique with the assumed-modes method. It is shown that, with the introduction of the three tuning parameters associated with the clamping radius of the disks, the stiffness of the cover and base structure and the radial stiffness of the bearings, the simulation model can well predict all the coupled modes of interest.
Effects of Head-Supported Devices on the Human and Manikin Necks
Authors: Ashrafiuon Hashem , Alem Nabih M. , McEntire B. Joseph 
Published: February 2021

Abstract
A comprehensive study of the effect of Head-Supported Devices (HSDs) on the neck loading during helicopter accidents is presented. The new Articulated Total Body (ATB) model which treats the neck as a deformable segment was used for crash simulation. Different categories of human and manikin subjects were considered under several crash scenarios. Simulations were theoretically designed to include a wide range of HSDs by changing their weights and C. G. (center of gravity) locations relative to the head and studying the effects of these changes. HSDs were only included as added weight and inertia to the head and their possible detachment has not been modeled in the study. Hence, two typical detachable devices were modeled and selected simulations were repeated and compared not only to provide a theoretical measure of accuracy for the original results but also to see the effect of separation of these devices from the helmet.
Testing Machines for Vibration Levels on a Test-Bed Mounting Which Is Not Similar to the Application Mounting
Authors: Lau Wai Shing , Garvey S. D. , Penny J. E. T. 
Published: February 2021

Abstract
Determining the level of force transmitted by a machine to its final mounting is of interest to a machine manufacturer especially if it can be done at the factory or even at the site using accelerometers. This paper examines the theoretical and practical aspects of such tests when the machine is to rigidly mounted, and when the manufacturer’s test-bed is not necessary the same as the actual final mounting. A simulated model and an experiment are described, including the difficulties associated with the conduct of similar tests. The level of force calculated is typically higher than that actually measured (for comparison).
Effect of Flexibility in Transverse Impact Problems
Authors: Yigit Ahmet S. , Christoforou Andreas P. 
Published: February 2021

Abstract
The nature of impact response of a flexible body is studied. The key parameters which govern the nature of impact response are identified. The effects of these parameters on the impact response are examined through numerical simulations. It is shown that the normalized impact force and the type of impact response can be predicted through the functional relationship between the normalized maximum impact force and two nondimensional parameters termed as “loss factor” and “relative stiffness”. It is expected that the results of this study will be of great value in choosing adequate impact and computational models for the dynamic analysis of multibody systems subject to transverse impacts.
Modeling a Robot With Flexible Joints and Decoupling its Equations of Motion
Authors: Meghdari Ali , Fahimi Farbod 
Published: February 2021

Abstract
Recent advances in the study of dynamics of multibody systems indicate the need for decoupling of the equations of motion. In this paper, our efforts are focused on this issue, and we have tried to expand the existing methods for multi-rigid body systems to include systems with some kind of flexibility. In this regard, the equations of motion for a planar two-degree-of-freedom robot with flexible joints is carried out using Lagrange’s equations and Kane’s equations with congruency transformations. The method of decoupling the equations of motion using Kane’s equations with congruency transformations is presented. Finally, the results obtained from both methods are compared.
New Component Modes for Flexible Multibody Systems
Authors: Verlinden O. , Dehombreux P. , Conti C. 
Published: February 2021

Abstract
In multibody systems, the deformation of a flexible body is generally modelled by a weighted summation of previously chosen deformation modes. Mode sets composed of static and vibration modes, which proved efficient in structural analysis, are commonly used in practice.
The paper presents how the classical reductions can be adapted to better fit the peculiarities of multibody systems. It is first shown how the classical mode sets can be reorganized according to the particular kinematics of a flexible body, based on a body reference frame. Secondly, it is proposed to add acceleration modes to the classical reductions to better represent the deformation during large displacements. The importance of natural boundary conditions in multibody systems is also emphasized.
The benefit of the acceleration modes and the interest of coherent natural boundary conditions are illustrated on the example of a railway engine, for two different analyses, by means of an expressly developed quality test.
A Strategy to Accelerate the Numerical Integration in the Dynamic Simulation of Multibody Systems
Authors: Cardenal Jesús , Cuadrado Javier , Bayo Eduardo 
Published: February 2021

Abstract
This paper presents a multi-index variable time step method for the integration of the equations of motion of constrained multibody systems in descriptor form. The basis of the method is the augmented Lagrangian formulation with projections in index-3 and index-1. The method takes advantage of the better performance of the index-3 formulation for large time steps and of the stability of the index-1 for low time steps, and automatically switches from one method to the other depending on the required accuracy and values of the time step.
The variable time stepping is accomplished through the use of an integral of motion, which in the case of conservative systems becomes the total energy. The error introduced by the numerical integrator in the integral of motion during consecutive time steps provides a good measure of the local integration error, and permits a simple and reliable strategy for varying the time step. Overall, the method is efficient and powerful; it is suitable for stiff and non-stiff systems, robust for all time step sizes, and it works for singular configurations, redundant constraints and topology changes. Also, the constraints in positions, velocities and accelerations are satisfied during the simulation process. The method is robust in the sense that becomes more accurate as the time step size decreases.
Experiments for Damage Location in a Damped Structure
Authors: Smith Suzanne Weaver , Zimmerman David C. , Bartkowicz Theodore J. , Kim Hyoung M. 
Published: February 2021

Abstract
In this paper, we present the results of an investigation of significant damping effects and the ability to locate damage. A three–bay, vertically cantilevered laboratory truss testbed was developed to exhibit beam–like response for the first three modes (a pair of first bending modes in orthogonal directions and a torsional mode). Truss members were removed from the testbed to simulate various damage scenarios with reduced stiffness. In addition, up to four visco–elastic damping struts were placed in the truss testbed in various configurations to affect the damping of certain modes of the structure. A comprehensive test matrix of damping and damage effects was designed and completed to construct the data base for the damping and damage identification evaluations. Two representative visco–elastic struts were also tested individually to determine their stiffness and damping characteristics. The damage detection process used the differences between pre- and post–damage vibration characteristics, along with a structural model, to successfully locate and quantify the extent of structural damage in all cases. Damping matrix models were also identified and evaluated.
Using Model Updating Technique to Train Neural Network for Fault Detection
Authors: Lopes Vicente , Pereira João Antonio , Weber Hans Ingo 
Published: February 2021

Abstract
Vibration monitoring and fault detection of components in manufacturing plants involve a detailed analysis of a collection of vibration data in order to establish a correlation among changes of the measured data and the corresponding fault. This work presents an alternative proposal which intent is to exploit the capability of model updating techniques associated to neural networks to reduce the amount of measured data. The updating procedure supplies a reliable model that permits to simulate any damage condition, which allows to establish a direct correlation between the deviation of the response and the corresponding fault. The learning of the net is performed using a compressed spectrum signal created for each specific type of fault. Different fault conditions for a frame structure are evaluated using simulated data and finally, the capability of the proposal is demonstrated using experimental data.
An Object-Oriented Machine Condition Monitoring Scheme for Rotating Machinery
Authors: Bettig Bernhard P. , Han Ray P. S. 
Published: February 2021

Abstract
The increasing reliability and accuracy of sensors as well as improvements in data acquisition and display have lead to the predictive maintenance method of scheduling machinery overhauls and replacement. Numerical models of the dynamics of a machine may be used to more accurately predict and schedule maintenance by relating variables describing deterioration mechanisms to machine measurements. For instance, vibration measurements may be used to determine bearing stiffness which is then trended. The present paper describes the concepts of a program to interactively examine and predict the health of a rotating machine. To facilitate a user-friendly implementation of the method, the paper also presents an object-oriented framework approach for introducing GUI-based graphics.
Application of Parametric Uncertainty Modeling to a Flexible Structure
Authors: Wolodkin G. , Nalbantoğlu V. , Lim K. B. , Balas G. J. 
Published: February 2021

Abstract
We present the results of a study in uncertainty modeling applied to the flexible structure at the University of Minnesota. In addition to additive and multiplicative uncertainty models, we examine parametric uncertainty descriptions in which the weights are obtained directly from input-output data. Two methods are examined, one based on a minimum norm model validation (MNMV) test and another in which the estimated co-variance of the parameters is used to arrive at the uncertainty weights. The resulting uncertainty models are then used to design μ-synthesis controllers, and the resulting closed-loop performance is evaluated. Additional data is taken in a closed-loop setting, and this data is used to refine the model. For the flexible structure studied, we show that the use of parametric uncertainty leads to higher performance than that attainable with purely additive or multiplicative uncertainty. Refinement of the model based on closed-loop data is also shown to result in increased performance.
A Feedforward Correction Method for Multi-Shaker Excitation System in Sine Testing
Authors: Bucher I. 
Published: February 2021

Abstract
In experiments aimed at structural dynamics testing, it is often required to precisely control a multi-shaker system in order to replicate the conditions a machine experiences during typical operation mode. For that purpose one seeks to create a specific pattern of responses or forces motivated by actual measured data. Another use of such tuning is for diagnostic purposes where certain forcing patterns amplify hidden features of the dynamic response. For lightly-damped structures that are normally excited by magnetic or electro-magnetic shakers, this task appears to be difficult, especially when high accuracy is desired. The excitation system, under certain conditions, creates an inherent feedback between the force and the response and often some non-linearity exist in the force path. In this paper, a systematic approach for automatic tuning the amplitude and phase of a multi-shaker in an experimental system is developed. The method is particularly useful in the presence of feedback, mild non-linearity and coupling between the force and response. The usual approach is to use a linear model and to assumed that the non-linearity is small, an approach that is valid for identification of slightly non-linear structures, but which fails when precise tuning of forces is based on this identified model. It is therefore suggested to use a general linearized model, rather than a linear one, so that any irregularities attributed to the non-linearity can be handled. Throughout the paper some simulated and experimental examples of tuning are shown. The interaction mechanism between the shakers and the structure is discussed and modeled and an appropriate strategy allowing us to overcome the demonstrated difficulties, is presented.