bluuebunny/crossref_metadata_2025_split huggingface dataset:
Surface Topography and Noise Emission in Gearboxes
Authors: Amini Naser , Rosén B. G. 
Published: February 2021

Abstract
This paper, by the experimental investigation, deals with the effect of different surface topographies on noise generation in gears. Results from the noise assessment of one gear before and after honing are discussed. The honing operation was applied to the gear after the grinding. The gear was tested in an actual gearbox, operated in a test rig. Running conditions were systematically changed during the test; however, the same conditions were utilized for the gear before and after honing. The aim of the study was to identify the mechanism of the expected noise reduction, with surfaces being evaluated in 3D.
The following results have been obtained: The total energy in the noise decreases significantly. The magnitude of the tooth-mesh frequency dose not change, but the level of its higher harmonics decreases significantly. These reductions are especially significant, when running at higher rotational speeds or when the applied torque is increased.
Computational Issues in Damping Identification for Large Scale Problems
Authors: Pilkey Deborah F. , Roe Kevin P. , Inman Daniel J. 
Published: February 2021

Abstract
Damage detection and diagnostic techniques using vibration responses that depend on analytical models provide more information about a structure’s integrity than those that are not model based. The drawback of these approaches is that some form of a workable model is required. Typically, models of practical structures and their corresponding computational effort are very large. One method of detecting damage in a structure is to measure excess energy dissipation, which can be seen in damping matrices. Calculating damping matrices is important because there is a correspondence between a change in the damping matrix and the change in the health of a structure. The objective of this research is to investigate the numerical problems associated with computing damping matrices using inverse methods.
Two damping identification methods are tested for efficiency in large-scale applications. One is an iterative routine, and the other a least squares method. Numerical simulations have been performed on multiple degree-of-freedom models to test the effectiveness of the algorithm and the usefulness of parallel computation for the problems. High Performance Fortran is used to parallelize the algorithm.
Efficient Structural Acoustic Analysis Using Finite and Infinite Elements and Parallel Processing Architectures
Authors: Moore Stewart W. , Allik Henno 
Published: February 2021

Abstract
The analysis of three-dimensional shell structures submerged in an infinite fluid and subjected to arbitrary loadings is a computationally demanding problem regardless of the analytical technique used. Over the past several years, we have developed a combined finite/infinite element method of solving this class of problems that is more efficient than other available techniques, and have implemented it in a comprehensive set of computer programs called SARA.
This paper presents an overview of our work in parallizing this software. In the first part of the paper, we describe our method for solving the fluid-structure interaction equations including infinite element theory, and modeling practices that have evolved for solving cylindrical geometries.
The second part of the paper addresses parallalization of SARA-3D on both shared and distributed memory architectures. The SARA implementation of the method is described along with sample problems, and a comparison to a SARA-3D solution is provided.
Finite Element Methods for the Radiation of Ultrasonic Phased Arrays Into an Acoustic Medium
Authors: Grosh Karl , Dodson John M. , Lin Yuan 
Published: February 2021

Abstract
In this paper, the dynamic response of a piezoelectric transducer in contact with an acoustic media is formulated. This serves as a model problem for an ultrasonic phased array in contact with the human body. These arrays may be used for hyperthermia or ablation surgery; the focus of this paper, however, is the efficient numerical formulation for modeling the array problem. Efficient numerical methods will provide a useful design tool and allow for the investigation of structural–acoustic phenomena. A finite element formulation based on Galerkin and Galerkin Least Squares (GLS) methods is presented. The benefits of the GLS method over the standard Galerkin method are demonstrated through numerical experiments of the dynamic response of a multi–element array. The methods under development can be applied to any fluid structure interaction problem and point strongly to the advantage of GLS methods for mid– and high–frequency applications. The accuracy of approximate versus exact non–reflecting, truncation boundary conditions is discussed.
Effect of Dynamic Shear Force on Fastener Loosening in Assemblies
Authors: Dong Yubo , Hess Daniel P. 
Published: February 2021

Abstract
Placement and orientation of fasteners in assemblies is generally based on convenience or static load and strength considerations. Vibration and other dynamic loads can result in loosening of threaded product, particularly when cyclic shear stresses are present. This paper investigates the placement of a bolt and nut on a compound cantilever beam subjected to dynamic inertial loading. Calculations for an inertial loaded, cantilever, Euler-Bernoulli beam show that the dynamic shear stress is maximum near the dynamic nodal lines, and essentially vanishes near the anti-nodes. Experiments with a compound cantilever beam assembly with one fastener reveal that loosening occurs more readily when the bolt and nut are placed near a nodal line. Data presented include time to loosen, break-away torque, and acceleration level. The data shows that fastener integrity is maintained for longer periods of time and with lower tightening torques, when the bolt and nut are positioned away from nodal lines where shear stresses are lower, even though acceleration levels are higher.
Precision Placement Analysis of a New Multi-DOF Piezoelectric End-Effector via Finite Elements
Authors: Bahrami Hassan , Tzou H. S. 
Published: February 2021

Abstract
Piezoelectric materials are increasingly being applied to various fieldS of research and engineering applications. In recent years for example, much work has been concentrated on active vibration control of structures by incorporating piezoelectric as both sensorS and actuators. In the industry, piezoelectrics are widely being accepted as effective sensors, giving engineers more leverage to add new features to their products. In this paper, piezoelectric composite structure is studied for precision placement of a multiple degrees off freedom (DOF) end–effector per the converse piezoelectric effect. This new design of the multi–DOF cantilever beam, by attaching multiple piezoelectric rectangular rods together, will provide a way to accurately position the end of this beam structure. The computation of this advanced composite structure is done by the finite element method incorporating the piezoelectric effects.
A Global Methodology for the Modal Reduction of Large Nonlinear Systems Containing Quadratic and Cubic Nonlinearities
Authors: Pesheck E. , Pierre C. 
Published: February 2021

Abstract
A methodology is presented for the systematic modal reduction of structural systems which contain quadratic and cubic nonlinearities in displacement. The procedure is based on the center manifold approach for describing individual nonlinear modes, but it has been extended to account for simultaneous motion within several chosen modal coordinates. Motions of the reduced system are constrained to lie on high-dimensional manifolds within the phase space of the original system. Polynomial approximations of these manifolds are obtained through third order for arbitrary system parameters. Algorithms have been developed for automation of this procedure, and they are applied to an example system. Free and forced responses of the reduced system are discussed and compared to responses reduced through simple modal truncation. A more rigorous treatment of harmonic forcing is proposed, which will allow for the production of high-dimensional, time-dependent manifolds through a simple adaptation of the unforced procedure.
Nonlinear Normal Modes of Buckled Beams: Three-to-One and One-to-One Internal Resonances
Authors: Nayfeh Ali H. , Lacarbonara Walter , Chin Char-Ming 
Published: February 2021

Abstract
Nonlinear normal modes of a buckled beam about its first buckling mode shape are investigated. Fixed-fixed boundary conditions are considered. The cases of three-to-one and one-to-one internal resonances are analyzed. Approximate expressions for the nonlinear normal modes are obtained by applying the method of multiple scales to the governing integro-partial-differential equation and boundary conditions. Curves displaying variation of the amplitude with the internal resonance detuning parameter are generated. It is shown that, for a three-to-one internal resonance between the first and third modes, the beam may possess either one stable mode, or three stable normal modes, or two stable and one unstable normal modes. On the other hand, for a one-to-one internal resonance between the first and second modes, two nonlinear normal modes exist. The two nonlinear modes are either neutrally stable or unstable. In the case of one-to-one resonance between the third and fourth modes, two neutrally stable, nonlinear normal modes exist.
Nonlinear Nonplanar Dynamics of Parametrically Excited Cantilever Beams
Authors: Arafat Haider N. , Nayfeh Ali H. , Chin Char-Ming 
Published: February 2021

Abstract
The nonlinear nonplanar response of cantilever inextensional metallic beams to a principal parametric excitation of two of its “exural modes, one in each plane, is investigated. The lowest torsional frequencies of the beams considered are much larger than the frequencies of the excited modes so that the torsional inertia can be neglected. Using this condition as well as the inextensionality condition, we develop a Lagrangian whose variation leads to the two integro-partial-differential equations of Crespo da Silva and Glynn. The method of time-averaged Lagrangian is used to derive four first-order nonlinear ordinary-differential equations governing the modulation of the amplitudes and phases of the two interacting modes. The modulation equations exhibit the symmetry property found by Feng and Leal by analytically manipulating the interaction coefficients in the modulation equations obtained by Nayfeh and Pai by applying the method of multiple scales to the governing integro-partial-differential equations. A pseudo arclength scheme is used to trace the branches of the equilibrium solutions and an investigation of the eigenvalues of the Jacobian matrix is used to assess their stability. The equilibrium solutions experience pitchfork, saddle-node, and Hopf bifurcations. A detailed bifurcation of the dynamic solutions of the modulation equations is presented. Five branches of dynamic (periodic and chaotic) solutions were found. Two of these branches emerge from two Hopf bifurcations and the other three are isolated. The limit cycles undergo symmetry-breaking, cyclic-fold, and period-doubling bifurcations, whereas the chaotic attractors undergo attractor-merging and boundary crises.
PC Based Nonlinear Dynamic Simulation and Animation of the Tilting Pad Guide Bearing in Large Hydro-Unit
Authors: Zhang X. Z. , Ma L. F. , Zhao Y. C. 
Published: February 2021

Abstract
The paper describes a process with which the nonlinear dynamical simulation and the animation of tilting pad guide bearing in large hydro-unit can be performed on a PC computer. Based on non-stationary Reynolds equation the effects of the nonlinear displacement and velocity of journal center as well as the nonlinear swing angle and velocity of pad on oil film forces are taken into consideration. The animation displays vividly the pictures of the rotation of shaft, the movement of journal center and the swing motion of pad. As an example, the response due to momentarily created unbalance is given.
Dynamic Analysis of a Ramp-Roller Clutch
Authors: Chang Chin-Tzung , Seireg Ali A. 
Published: February 2021

Abstract
This study deals with the design and dynamic analysis of a ramp-roller clutch which can be utilized in developing a mechanical function generator. The dynamic behavior with non-linear torsional spring and damping characteristics is first investigated. Three major design parameters are identified and further optimized for the objective of minimizing the settling time. As a result of underdamping, undesired vibration can occur during the engagement. In order to minimize these unwanted vibrations, coulomb dampers are considered. By adding a properly tuned auxiliary damper, the settling time can be significantly reduced. An example is also given to illustrate the use of one-directional clutches for mechanical function generation where an arbitrary function is synthesized by sequentially triggering 7 clutches. Phase shifting is incorporated in the to reduce the error in the generated function.
Dynamics of a Rotating System With a Nonlinear Eddy-Current Damper
Authors: Kligerman Yuri , Gottlieb Oded 
Published: February 2021

Abstract
The investigation of nonlinear dynamics and stability of a rotating system with an electromagnetic non-contact eddy-current damper is carried out. The damper is modeled by a thin nonmagnetic disk that is translating and rotating with a shaft in an air gap of a direct current electromagnet. The damper dissipates energy of the rotating system lateral vibration through induced eddy-currents. The dynamical system also includes a cubic restoring force representing nonlinear behavior of rubber o-rings supporting the shaft. The equilibrium state of the balanced rotating system with an eddy-current damper becomes unstable via a Hopf bifurcation and exact solutions for the limit cycle radius and frequency of the self-excited oscillation are obtained analytically. Forced vibration induced by the rotating system mass imbalance is also investigated analytically and numerically. System response includes periodic and quasiperiodic solutions. Stability of the periodic solutions obtained from the balanced self-excited motion and the unbalance forced response is analyzed by use of Floquet theory. This analysis enables an explanation of the nonlinear dynamics and stability phenomena documented for rotating systems controlled by electromagnetic eddy-current dampers.
Evaluation of AMB Turbomachinery Auxiliary Bearings
Authors: Kirk R. G. 
Published: February 2021

Abstract
The use of active magnetic bearings (AMB) for turbomachinery has experienced substantial growth during the past two decades. The advantages for many applications make AMB’s a very attractive solution for potentially low loss and efficient support for both radial and thrust loads. New machinery must be shop tested prior to shipment to the field for installation on-line. For AMB turbomachinery, one additional test is the operation of the auxiliary drop or overload bearings. A major concern is ability of the selected auxiliary bearing to withstand the contact forces following an at speed rotor drop. The proper design of AMB machinery requires the calculation of the anticipated loading for the auxiliary bearings. Analytical techniques to predict the rotor transient response are reviewed. Results of transient response evaluation of a full-size compressor rotor are presented to illustrate some of the important parameters in the design for rotor drop.
Vibrations of Ballooning Elastic Strings
Authors: Zhu Fang , Sharma Rajiv , Rahn Christopher D. 
Published: February 2021

Abstract
This paper investigates the nonlinear dynamic response of a linearly elastic string fixed at one boundary and undergoing constant speed circular motion at the other boundary. The response divides into nonlinear, steady state ballooning that is fixed relative to a rotating coordinate system and linearized vibration about the steady state. Single loop balloons have high tension and purely imaginary eigenvalues. The single loop vibration frequencies generally decrease with increasing balloon length. Highly extensible strings whirl in first and higher modes with forward whirling modes having lower frequencies. Axially stiff strings exhibit whirling only in higher modes. If the nondimensional string stiffness is larger than 1000 then the inextensible steady state solutions and the lowest six vibration frequencies match the extensible results to within 3%. One and a half loop balloons are divergently unstable. Long and/or sufficiently extensible strings form low tension double loop balloons. Inextensible double balloons are coupled mode flutter unstable. The steady state balloons, steady state eyelet tension, and balloon stability are experimentally verified.
Parametric Identification of Nonlinear Systems Using Higher-Order Spectra
Authors: Khan Khalil A. , Balachandran B. 
Published: February 2021

Abstract
A novel procedure to parametrically identify the nonlinearities in a system is presented. In this procedure, the relationships among higher-order transfer functions and higher-order spectra are utilized and expressions are derived for coefficients of non-linearities. Two different nonlinear oscillators are considered as examples to illustrate the procedure. Numerical results are also provided for a nonlinear oscillator.
The Dynamics of the Celt With Second Order Averaging and Computer Algebra
Authors: Blackowiak A. D. , Rand R. H. , Kaplan H. 
Published: February 2021

Abstract
Starting with a no-slip, dissipation-free model of the celt developed by Kane and Levinson in 1982, we obtain a three-dimensional slow flow using second order averaging. The coefficients of the slow flow are obtained in symbolic form through the use of computer algebra, thus permitting a bifurcation analysis to be performed. It is shown that for all physically relevant parameters the celt is predicted to exhibit an infinite number of spin reversals. The analysis assumes small energy and small inertial asymmetry.
Canonical Perturbation of a Fast Time-Periodic Hamiltonian via Liapunov-Floquet Transformation
Authors: Butcher Eric A. , Sinha S. C. 
Published: February 2021

Abstract
In this study a possible application of time-dependent canonical perturbation theory to a fast nonlinear time-periodic Hamiltonian with strong internal excitation is considered. It is shown that if the time-periodic unperturbed part is quadratic, the Hamiltonian may be canonically transformed to an equivalent form in which the new unperturbed part is time-invariant so that the time-dependent canonical perturbation theory may be successfully applied. For this purpose, the Liapunov-Floquet (L-F) transformation and its inverse associated with the unperturbed time-periodic quadratic Hamiltonian are computed using a recently developed technique. Action-angle variables and time-dependent canonical perturbation theory are then utilized to find the solution in the original coordinates. The results are compared for accuracy with solutions obtained by both numerical integration and by the classical method of directly applying the time-dependent perturbation theory in which the time-periodic quadratic part is treated as another perturbation term. A strongly excited Mathieu-Hill quadratic Hamiltonian with a cubic perturbation and a nonlinear time-periodic Hamiltonian without a constant quadratic part serve as illustrative examples. It is shown that, unlike the classical method in which the internal excitation must be weak, the proposed formulation provides accurate solutions for an arbitrarily large internal excitation.
Interrelation of Self-Excited Friction Vibrations With Thermal Processes in Brakes
Authors: Gekker Feodor R. , Chichinadze Avtandil V. , Khairaliev Serik I. , Suvorov Aleksey V. 
Published: February 2021

Abstract
The method results of the self-excited friction vibrations calculation in brake systems is presented. The problem of obtain some parameters necessary for calculation has received special attention.
Lateral Vibration of a Consistent Continuous Beam With a Crack
Authors: Chondros Thomas G. , Dimarogonas Andrew D. , Yao Jonathan 
Published: February 2021

Abstract
A continuous cracked beam vibration theory is developed for the lateral vibration of cracked Euler-Bernoulli beams with single-edge or double-edge cracks. The Hu-Washizu-Barr variational formulation was used to develop the differential equation and the boundary conditions of the cracked beam as an one-dimensional continuum. The displacement field about the crack was used to modify the stress and displacement field throughout the bar. The crack was modelled as a continuous flexibility using the displacement field in the vicinity of the crack, found with fracture mechanics methods.
The results of three independent evaluations of the lowest natural frequency of lateral vibrations for beams with a single-edge crack are presented: the continuous cracked beam vibration theory developed here, the lumped crack beam vibration analysis, and an asymptotic solution. Experimental results from aluminum beams with fatigue cracks are very close to the values predicted. A steel beam with a double-edge crack was also investigated with the above mentioned methods, and results compared well with experimental data.
Effect of the Gravity Force on the Propagation of a Rotating Flexible Rod After Impact
Authors: Gau Wei-Hsin 
Published: February 2021

Abstract
The aim of this paper is to analyze the effect of the gravity force on the impact-induced elastic waves which propagate on a radially rotating rod. The equations of motion of the system are developed using the principle of virtual work in dynamics. The impact load is included by the use of the generalized impulse momentum equations, involving the coefficient of restitution. The system is solved using the Fourier method. The deformation of the rod is supposed to be at any instant a linear combination of a set of shape functions. These shape functions are, in this investigation, the modes of a cantilever beam. The weight of the rod is modeled as a concentrated force applied at any instant at the center of the rod.
Autonomous Modal Identification of the Space Shuttle Tail Rudder
Authors: Pappa Richard S. , James George H. , Zimmerman David C. 
Published: February 2021

Abstract
Autonomous modal identification automates the calculation of natural vibration frequencies, damping, and mode shapes of a structure from experimental data. This technology complements damage detection techniques that use continuous or periodic monitoring of vibration characteristics. The approach shown in the paper incorporates the Eigensystem Realization Algorithm (ERA) as a data analysis engine and an autonomous supervisor to condense multiple estimates of modal parameters using ERA’s Consistent-Mode Indicator and correlation of mode shapes. The procedure was applied to free-decay responses of a Space Shuttle tail rudder and successfully identified the seven modes of the structure below 250 Hz. The final modal parameters are a condensed set of results for 87 individual ERA cases requiring approximately five minutes of CPU time on a DEC Alpha computer.
Experimental Validation and Modal Analysis for a Highway Bridge
Authors: Sun Jinghui , Pang Jian , Song Gang , Patten William N. 
Published: February 2021

Abstract
This paper presents preliminary results of an experimental investigation of the modal characteristics of a 400′ continuous composite girder highway bridge on U.S. Interstate 35. The test data is compared to an analytical model based on the finite element (FE) method. An impact hammer was used as an exciter, and the bridge acceleration response was measured at 36 points. The results indicate that the analytical model can faithfully predict the modal response of the bridge.