bluuebunny/crossref_metadata_2025_split huggingface dataset:
Simplified Dispersion Relations for Floquet Waves in a Plate With Multiple Arrays of Attachments
Authors: Gueorguiev Dimitar , McDaniel J. Gregory , DuPont Pierre 
Published: February 2021

Abstract
Recently, the authors developed analytical expressions for the dispersions of Floquet waves that propagate in a structure consisting of a plate with multiple arrays of line attachments. The dispersions of these Floquet waves, and in particular the imaginary parts of their wavenumbers, quantify the attenuation of vibrational energy in space as the frequency of a local excitation is varied. Understanding how the parameters of the attached structures, such as their spacings and impedances, affect the Floquet wave dispersions could provide further means to include consideration of energy localization or distribution in the structural design process. Such an understanding is developed in the present work by identifying those cases in which the treatment of certain arrays can be greatly simplified. In particular, limiting cases of small and large array spacings are investigated for which the treatment of particular arrays can be greatly simplified. Such simplifications are not immediately obvious without access to analytical expressions for the Floquet wavenumbers, as the dynamics of all arrays are coupled through the plate. Results presented here will aid the structural design community by indicating which design changes most effectively control energy distribution and by indicating when simplified finite element models of multiple-array structures are possible.
Free Vibration of Coupled Disk-Hat Structures
Authors: Bae Jun-Chul , Wickert Jonathan 
Published: February 2021

Abstract
The free vibration of disk-hat structures, such as automotive brake rotors, is investigated analytically and through laboratory experimentation. Of particular interest are the role played by the hat element’s depth in influencing the three-dimensional vibration of the disk, and the manner in which the bending and in-plane modes of the disk alone evolve as a hat of increasing depth is incorporated in the model. The lower vibration modes of disk-hat structures are shown to be characterized by the numbers of nodal circles NC and diameters ND present on the disk, as well as the phase relationship between the disk’s transverse and radial displacements due to coupling with the hat element. Such modes map continuously back to the pure bending and in-plane modes of the disk alone, appear in ordered pairs, and can exist at close frequencies. Those characteristics are explored particularly with respect to sensitivities in the disk’s thickness and the hat’s depth with a view towards shifting particular natural frequencies, or minimizing transverse disk motion in certain vibration modes. Results obtained through analysis and measurement of a prototypical disk-hat structure are applied in a case study with a ventilated automotive brake rotor.
A Free-Free Beam Rotationally Restrained at One End
Authors: Hirsch Richard A. 
Published: February 2021

Abstract
In ground vibration testing of flexible missiles to determine their in-flight vibration modes, it is desirable that the support stiffness be as small as possible relative to the missile beam stiffness. This paper analyzes the effect of a rotational stiffness applied to one end of a uniform free-free beam. The changes in the natural frequency and node locations for the first two modes are calculated as a function of the support stiffness. The Saturn V Apollo Launch Vehicle is used as a numerical example.
Gyro Drift Calibration in Low Cost Inertial System
Authors: Zhao Zhong , Ma Rong , Zhang Weiguo 
Published: February 2021

Abstract
An intelligent gyro drift calibration method for low-cost inertial system is presented in this paper. This method based on fuzzy reasoning and dynamic estimation can calibrate time-varying gyro drift in the motion of vehicle. Experiments have been done on three strapdown inertial all-attitude systems constituted of piezoelectric rate gyros. The result shows that this method is effective by which the residual of piezoelectric gyro drift can be reduced to about one percent of its original drift value.
Genetic Optimization Applied to the Dynamic Design of an Engine Cradle
Authors: Baldanzini Niccolò , Citti Paolo , Pierini Marco 
Published: February 2021

Abstract
An innovative approach to dynamic design is presented that has the notable advantage of allowing the dynamic requirements to be specified from the earliest design stage. The method applies genetic algorithms to optimize the dynamic behavior of the engine-cradle system and its links to the chassis. The optimization minimizes the sum of the amplitudes of the forces transmitted to the chassis, while complying with the static and dynamic constraints. The genetic algorithm was applied to a multibody system model of the engine-cradle system and its links to derive new, improved configurations.
Genetic Algorithm Approach for Optimization of FRP Laminated Cylindrical Shells Under Constraint
Authors: Ohta Yoshiki 
Published: February 2021

Abstract
Fiber Reinforced Plastic (FRP) materials have been increasingly used in many structural applications of space shuttles, airplanes and automobiles, and the structural optimization of FRP laminated composite shells has been studied for stiffer structural design by many researchers. This paper studies the maximization of fundamental frequencies of FRP laminated cylindrical shells under stiffness constraint by using Genetic Algorithm (GA). For this purpose, the frequency equation for simply-supported shells with symmetrically balanced stacking sequence is derived analytically based on Classical Lamination Theory. In optimization the fiber angles and the thickness ratio of each FRP ply, which have continuous real values, are taken as design variables, and fundamental frequency of the shell is maximized under in-plane stiffness constraints. In numerical experiments, extensive numerical calculations are carried out to determine better genetic operators that would be suitable for FRP laminates design, and genetic parameters are tuned for better reliabilities and lower computational costs in the present GA. Optimal design solutions for various laminated cylindrical shells are obtained and then the applicability of the GA to the maximization of frequencies of the shells is studied from numerical results obtained.
An Impact Oscillator With Finite Time Collisions
Authors: Quinn D. Dane 
Published: February 2021

Abstract
We study a simple one-and-a-half degree-of-freedom impact oscillator in which the dynamical behavior is characterized by two regimes — modeling contact and non-contact dynamics, subject to a description of the impactive event. The contact is modeled as a linearly elastic element and the time interval over which contact occurs is of finite duration. This model allows for a coefficient of restitution to be defined which depends on not only the system parameters, but the relative velocity at the point of impact. For sufficiently small impact velocities the colliding bodies remain in contact while for larger relative speeds, the coefficient of restitution is positive. With this model for the collision, an impact oscillator is described and is shown to contain rich dynamical behavior, including periodic and non-periodic motions.
Forced Vibration of Elastic Structures With Friction Contacts
Authors: Sextro Walter 
Published: February 2021

Abstract
In many technical contacts energy is dissipated because of dry friction and relative motion. This can be used to reduce the vibration amplitudes. For example, shrouds with friction interfaces are used to reduce the dynamic stresses in turbine blades. The three-dimensional motion of the blades results in a three-dimensional relative motion of the contact planes. The developed Point-Contact-Model is used to calculate the corresponding tangential and normal forces for each contact element. This Point-Contact-Model includes the roughness of the contact surfaces, the normal pressure distribution due to roughness, the stiffness in normal and tangential direction and dry friction. An experiment with two non-Hertzian contacts is used to verify the developed contact model. The comparison between measured and calculated frequency response functions for three-dimensional forced vibrations of the elastic structures shows a very good agreement.
Effects of Clearance on Normal Mode Frequencies of a Nonsmooth System
Authors: Butcher Eric A. 
Published: February 2021

Abstract
The effects of a clearance or interference on the normal mode frequencies of a two-dof system with bilinear stiffness and without damping are investigated through various modifications of the bilinear frequency relation. First, the exact bilinear natural frequencies of a single degree-of-freedom system are analytically obtained in terms of the amount of clearance and the strength of nonlinearity, and an equivalent linear system is derived. These results are in turn used to construct three methods which approximate the bilinear frequencies for the 2-dof system in which the resulting approximate frequencies are compared with those obtained from numerical simulations. The results demonstrate how these bilinear normal mode frequencies vary with the magnitude of the clearance/interference and thus point toward the need of including such effects in methods which utilize the bilinear frequency relation.
Mesoscale Dynamic Ice Formation and Breaking on a Vibrating Thin Membrane
Authors: Fullilove Jeff , Miller Norman , Shannon Mark , Philpot Michael , Vakakis Alexander , Georgiadis John , Ge Hongming 
Published: February 2021

Abstract
We study dynamic ice formation and breaking (IF/B) on a thin vibrating membrane. The complicated discontinuous dynamics of the membrane is studied experimentally using laser vibrometry. Although the fluid- and coolant-membrane interaction with simultaneous ice forming and breaking is a complicated dynamical phenomenon, the average rate of ice formed and broken can be approximately quantified. The analytical results are compared to experimental measurements.
Characteristic Constraint Modes for Component Mode Synthesis
Authors: Castanier Matthew P. , Tan Yung-Chang , Pierre Christophe 
Published: February 2021

Abstract
In this paper, a technique is presented for improving the efficiency of the Craig-Bampton method of Component Mode Synthesis (CMS). An eigenanalysis is performed on the partitions of the CMS mass and stiffness matrices that correspond to the so-called constraint modes. The resultant eigenvectors are referred to as “characteristic constraint modes,” since they represent the characteristic motion of the interface between the component structures. By truncating the characteristic constraint modes, a CMS model with a highly-reduced number of degrees of freedom may be obtained. An example of a cantilever plate is considered. It is shown that relatively few characteristic constraint modes are needed to yield accurate approximations of the lower natural frequencies. This method also provides physical insight into the mechanisms of vibration transmission in complex structures.
Friction Control for Vibration Suppression
Authors: Gaul L. , Nitsche R. 
Published: February 2021

Abstract
Friction damping in bolted joint connections of large space structures turned out to be a major source of damping (Gaul and Bohlen, 1987). For vibration suppression, the joints are designed such that the normal force in a frictional interface is controlled which improves damping performance. The use of active control to vary the normal contact force in a joint by means of a piezoelectric element is explored. A model consisting of two elastic beams connected by a single active joint is considered. A friction model with velocity dependent dynamics is used to describe the friction phenomena. A control law for friction dampers which maximizes energy dissipation instantaneously by controlling the normal force at the friction interface is proposed. The effect of displacement- and velocity-induced friction dynamics is considered for the design of the control law. We arrive at a dynamic controller which prevents frictional energy stored as potential energy in a bristle model from being returned to the system.
Modeling Extruded Profiles for Railway Coaches Using SEA
Authors: Geissler Paul , Neumann Dirk 
Published: February 2021

Abstract
The acoustical properties of extruded profiles and typical trimmed wall constructions for railway coaches are reviewed. It will be shown how Statistical Energy Analysis (SEA) can be used to calculate these properties. Calculated and measured results for two different extruded profiles and three different trim constructions will be compared and discussed.
The Use of Experimental SEA for Modeling Road Noise in Cars
Authors: Hermans L. , De Langhe K. , Iadevaia M. 
Published: February 2021

Abstract
Over the last years, SEA has been recognized as a useful tool to model and analyze the high-frequency vibro-acoustic behavior of fully assembled complex structures. This paper discusses the experimental derivation of the loss factor model of a passenger car. The paper outlines the different steps which need to be taken to obtained a fully validated experimental SEA model. This includes the subdivision into subsystems, the PIM measurement campaign, the derivation of the loss factors and their associated confidence levels and the model validation. The paper further details how the experimental SEA model was used to quantify and investigate the airborne and structure-borne contributions to the interior noise level for a road noise test condition. The operational power inputs to the vehicle were indirectly determined from operational response measurements. A contribution analysis showed that airborne noise sources dominated structure-borne noise sources above 500Hz. A sensitivity study allowed to propose an effective design modification. This modification was implemented and successfully tested on the road.
Use of Measured Mobility to Improve SEA Predictions in the Mid-Frequency Range
Authors: Manning Jerome E. 
Published: February 2021

Abstract
Statistical energy analysis provides a technique to predict acoustic and vibration levels in complex dynamic systems. The technique is most useful for broad-band excitation at high frequencies where many modes contribute to the response in any given frequency band. At mid and low frequencies, the number of modes contributing to the response may be quite small. In this case SEA predictions show large variability from measured data and may not be useful for vibroacoustic design. This paper focuses on the use of measured data to improve the accuracy of the predictions. Past work to measure the SEA coupling and damping loss factors has not been successful for a broad range of systems that do not have light coupling. This paper introduces a new hybrid SEA technique that combines measured mobility functions with analytical SEA predictions. The accuracy of the hybrid technique is shown to be greatly improved at mid and low frequencies.
Time Lag in Handling Responses of Automobiles Induced by Steering/Suspension Compliance or Hysteresis
Authors: Park Jungho , Pan Zhijie 
Published: February 2021

Abstract
This study presents the effect of steering/suspension compliance and hysteresis on the time lag in handling responses of automobiles. A multi-body modeling approach is used to construct the tire, steering, and combined subsystem models. The tire subsystem model focuses on the tire lateral compliance induced time lag. The steering subsystem model focuses on steering/suspension compliance and hysteresis effect on the time lag. The combined model, which is an integration of the tire and steering subsystem models, is to show the combined effect of the subsystems. The simulation results show that the compliance and hysteresis in the steering and/or suspension subsystems are the sources of time lag in responses and that the hysteresis significantly increases the initial time lag.
Low Order Vibration Models for Tracked Vehicles
Authors: Scholar C. , Perkins N. C. , Ma Z.-D. 
Published: February 2021

Abstract
A vehicle track model is developed with the objective of providing new capabilities in modeling track vibration response. Understanding track vibration is essential to evaluating the durability of track components, the vibration energy transmitted to the vehicle, and the acoustic emission from the vehicle. A new element model is derived herein that represents a track span as a continuous elastic member with distributed inertia. This model captures the effects of static track sag. static and dynamic track tension, track translation speed, and the coupling of longitudinal and transverse track vibration. Results from a companion experimental study on a section of track support the use of this continuum approximation. The track element model is extended to describe an entire track circuit for an example military vehicle. An eigenanalysis of this circuit model leads to the system vibration modes that are subsequently employed in a low-order model for forced response. The forced response characteristics resulting from two major excitation sources, roadarm motion and polygonal action, are described. The modal content of the track response is then examined to determine the minimum size model required to describe track vibration. It is concluded that low-order system models may be developed as efficient alternatives to established large degree-of-freedom multi-body track models.
The Application of Non-Linear Boundary Conditions to a Linearly Elastic Model to Achieve Multi-State Structural Behavior in a Large-Displacement Mechanical System Simulation
Authors: McConville James B. 
Published: February 2021

Abstract
Structural elasticity is increasingly perceived as vital to the fidelity of Mechanical System Simulation (MSS) analyses of complex systems under-going large motion. The use of modal elastic system components subject to non-linear loading has become commonplace. An additional use of nonlinear boundary conditions is that of altering the linear elastic behavior of the system structure(s) to achieve multi-state elastic behavior from a single, linear structure. The method is used in this paper to simulate with ADAMS® the effect of an aircraft experiencing a partial structural failure as a result of a hard landing.
Elastic Forces and Coordinate Systems in the Finite Element Formulations
Authors: Berzeri Marcello , Campanelli Marcello , Shabana A. A. 
Published: February 2021

Abstract
The equivalence of the elastic forces of finite element formulations used in flexible multibody dynamics is the focus of this investigation. Two conceptually different finite element formulations that lead to exact modeling of the rigid body dynamics will be used. These are the floating frame of reference formulation and the absolute nodal coordinate formulation. It is demonstrated in this study that different element coordinate systems, which are used for the convenience of describing the element deformations in the absolute nodal coordinate formulation, lead to similar results as the element size is reduced. The equivalence of the elastic forces in the absolute nodal coordinate and the floating frame of reference formulations is shown. The result of this analysis clearly demonstrates that the instability observed in high speed rotor analytical models due to the neglect of the geometric centrifugal stiffening is not a problem inherent to a particular finite element formulation but only depends on the beam model that is used. Fourier analysis of the solutions obtained in this investigation also sheds new light on the fundamental problem of the choice of the deformable body coordinate system in the floating frame of reference formulation. A new method is presented and used to obtain a simple expression for the elastic forces in the absolute nodal coordinate formulation. This method, which employs a nonlinear elastic strain-displacement relationship, does not result in an unstable solution when the angular velocity is increased.
Quasi Exact Solutions for Some Elastodynamics Problems
Authors: Barraco André , Gilbert Marguerite 
Published: February 2021

Abstract
In this paper we develop the formulation for large displacement, large rotation, but small strain, for Timoshenko beam. The so-called “finite rotation vector” is used. Rather to use a finite element formulation we solve the exact semi-local differential equations, written in the actual configuration, using a space (finite difference method) and time (Runge Kutta method) integration scheme. This method is restricted to geometrically simple structures but is developed to validate FEM codes. We present a static and dynamic example.
A Hybrid Highly Parallelizable Algorithm for the Dynamics of Rigid Body Chain Systems
Authors: Duan Shanzhong , Anderson Kurt S. 
Published: February 2021

Abstract
The paper presents a new hybrid parallelizable low order algorithm for modeling the dynamic behavior of multi-rigid-body chain systems. The method is based on cutting certain system interbody joints so that largely independent multibody subchain systems are formed. These subchains interact with one another through associated unknown constraint forces f¯c at the cut joints. The increased parallelism is obtainable through cutting the joints and the explicit determination of associated constraint loads combined with a sequential O(n) procedure. In other words, sequential O(n) procedures are performed to form and solve equations of motion within subchains and parallel strategies are used to form and solve constraint equations between subchains in parallel. The algorithm can easily accommodate the available number of processors while maintaining high efficiency. An O[(n+m)Np+m(1+γ)Np+mγlog2Np](0&lt;γ&lt;1) performance will be achieved with Np processors for a chain system with n degrees of freedom and m constraints due to cutting of interbody joints.
Dynamics of Washing Machines: Mechanical Model and Simulation
Authors: Wagner Falk , Pfeiffer Friedrich 
Published: February 2021

Abstract
This paper deals with the dynamical behavior of washing machines. Due to large unbalance forces of the laundry during the spinning process a mechanical model has been established from d’Alambert’s principle that considers both the rigid body motion and the elastic vibrations. According to the complexity of the machine parts the results of a finite element mode shape analysis are used to describe the elastic behavior. The distinct bodies of the system are linked together through linear and nonlinear force elements resulting in the excitation of several machine orders. In order to verify the model, simulation results are compared with measurements.