bluuebunny/crossref_metadata_2025_split huggingface dataset:
Optimal Sensor and Actuator Configuration for Structural Identification
Authors: Papadimitriou C. , Christodoulou K. , Pavlidou M. , Karamanos S. A. 
Published: November 2020

Abstract
A methodology is presented for designing cost-effective optimal sensor and actuator configurations useful for structural model updating and health monitoring purposes. The optimal sensor and actuator configuration is selected such that the resulting measured data are most informative about the condition of the structure. This selection is based on an information entropy measure of the uncertainty in the model parameter estimates obtained using a statistical system identification methodology. The optimal sensor and actuator configuration is selected as the one that minimizes the information entropy. A discrete optimization problem arises which is solved efficiently using genetic algorithms. This study also addresses important issues related to robustness of the optimal sensor and actuator configuration to unavoidable uncertainties in the structural model, as well as issues related to the optimal sensor and actuator configurations designed to monitor multiple damage scenarios. The theoretical developments are illustrated by designing the optimal configuration for a 40-DOF two-dimensional truss structure subjected to an impulse hammer excitation.
Instant Chaos, Extreme Parametric Uncertainty, and Sustained Chaotic Transients in Nonlinear Continuum Mechanics
Authors: Schwartz Ira B. , Triandaf Ioana , Wood Yvette , Georgiou Ioannis T. 
Published: November 2020

Abstract
Bifurcation to high-dimensional hyperchaos is observed in a driven coupled pendulum-flexible rod system. When the rod is in resonance with the pendulum, the system changes from a low dimensional attractor to a high dimensional attractor abruptly. It is shown that high dimensional chaotic dynamics is hysteretic, and exhibits extreme sensitivity with respect to small parameter changes. Such sensitivity poses a problem in obstructing predictability in mechanics. A brief discussion of sustaining chaos to prevent resonance is included.
Biomechanical Considerations in Antenatal Care of High Risk Pregnancies
Authors: Bhat Rama B. , Bhat Padmavathi P. 
Published: November 2020

Abstract
Preterm labor is an important issue in the field of Obstetrics and Gynacology. The earlier the diagnosis, the better the prevention of preterm labor. This study examines the static and dynamic loads on the cervix, which is one of the causes of preterm labor, from a biomechanical point of view. A simple biomechanical model is formulated to assess the loads bearing on the cervix. Results indicate the need for extreme caution warranted in cases of high risk pregnancies in highly dynamic environments. In view of the very delicate nature of the issue, it is essential to formulate better simulation models using indirectly gathered data.
POD (K-L) Analysis of the Interaction Free Dynamics of a Beam/Pendulum Configuration: An Experimental Study
Authors: Georgiou Ioannis T. , Schwartz Ira B. 
Published: November 2020

Abstract
This work presents an analysis of the experimental free dynamics of a coupled beam/pendulum configuration. The analysis, which is based on the method of Proper Orthogonal Decomposition, identifies the characteristics of the active degrees-of-freedom dominating the dynamics. Depending on the level of energy a motion is initiated, the interaction dynamics bear distinct signatures of reduced slow dynamics and distinct signatures of the interaction dynamics created by instabilities of reduced slow and fast dynamics.
Dynamics and Control of an Elastic Guideway Under a Moving Mass
Authors: Reckmann Hanno , Popp Karl 
Published: November 2020

Abstract
Lightweight structures under moving loads occur in robotics, ground transportation and in space stations. Increasing velocities lead to an excitation of structural vibrations with high amplitudes. This phenomenon may affect the precision of machine tools and robots and the safety of transport operations. An example of such a lightweight structure is a flexible beam under a moving load. In this paper we investigate the possibility of active vibration control of the elastic beam using a king post truss system (KPTS). The system is excited by both a mass moving with constant velocity and a mass performing an accelerated motion. The aims are to minimize the vibrations of the system and the transverse deflections under the moving mass.
The system to be analysed and controlled is time variant due to the moving mass. The fast motion of the mass leads to a highly dynamic system with a fast changing system matrix. We use control inputs at fixed positions for control of the system with distributed parameters. The system is modelled by a finite element approach to implement the moving mass in the system description. To reduce the numerical complexity of the system a modal transformation is applied and numerical investigations of the system are performed.
We apply two different control strategies to reach the aims. The first one is an optimal discrete time approach which allows to reach both aims. The second one is an adaptive control strategy with a simple model to minimize the deflection under the moving mass. The numerical results are compared with experimental data. In the case of a constant mass velocity the optimal control strategy leads to a reduction of the deflection under the moving mass of more than 98% compared to the uncontrolled system. The reduction of the deflection under the moving mass applying adaptive control results in a smaller reduction of about 96%.
Parametric Control of an Axially Moving String via Fuzzy Sliding-Mode and Fuzzy Neural Network Methods
Authors: Lai Cheng-Liang , Huang Jeng-Sheng , Chao Chang-Po 
Published: November 2020

Abstract
The parametric fuzzy sliding mode control (FSMC) and parametric fuzzy neural network control (FNNC) methods, in the present study, is applied to suppress vibration of the axially moving string system, which is driven by adjusting the axial tension. Due to the difficulty of utilizing fuzzy logic control (FLC) to obtain the linguistic control rules, the stability and robustness are not guaranteed. The sliding-mode control is then incorporated in the scheme of FLC to generate the control rule bases in order to meet the requirement of stability and robustness. In additions, for the purpose of improving system performance, the Genetic Algorithm (GA) is applied to search for the optimal parameters of the fuzzy sliding mode controller. Beside the aforementioned method of fuzzy sliding mode control plus GA, the on-line learning algorithm Fuzzy Neural Network (FNN) accompanied with sliding mode characterization is also developed and applied to achieve control goal. In this method, the parameters of FNN are adjusted in the direction that minimizes sliding mode variables SṠ where S of the switching function for vibration suppression. Simulations are conducted to verify the effectiveness of control designs. The results show the performance of FSMC with GA in general is favorable to others.
Coupled Torsion-Lateral Stability of a Shaft-Disk System Driven Through a Universal Joint
Authors: DeSmidt Hans A. , Wang K. W. , Smith Edward C. 
Published: November 2020

Abstract
Understanding the instability phenomena of rotor-shaft and driveline systems incorporating universal joints is becoming increasingly important because of the trend towards light-weight, high-speed supercritical designs. A non-dimensional, periodic, linear time-varying model with torsional and lateral degrees-of-freedom is developed for a rotor shaft-disk assembly supported on a flexible bearing and driven through a U-Joint and stability is investigated with Floquet Theory. It is shown that the interaction between torsional and lateral dynamics results in new regions of parametric instability that have not been addressed in previous investigations. The presence of load inertia and misalignment causes dynamic coupling of the torsion and lateral modes, which can result in torsion-lateral instability for shaft speeds near the sum-type combinations of the torsion and lateral natural frequencies. The effect of angular misalignment, static load-torque, load-inertia, lateral frequency-split, and auxiliary damping on the stability of the system is studied over a range of shaft operating speeds. Also, the effectiveness of auxiliary lateral viscous damping as a means of stabilizing the system is investigated. Finally, a closed-form technique based on perturbation expansions is derived to determine the auxiliary damping necessary to stabilize the system for the least stable case (worst case).
Forced Dynamics of an Orbiting Conducting Tether
Authors: Pasca Monica 
Published: November 2020

Abstract
Orbiting electrodynamic tethered systems are subjected not only to the gravity gradient but also to the electromagnetic drag forces that are generated by the interaction of the current flowing in the tether with the local magnetic field, according to the Lorentz law. This feature makes it possible to think of using such a system in order to de-orbit a satellite at the end of its life, taking advantage of the orbital energy lost in producing electric power.
The configuration of such a system is deeply discussed in this paper with reference to a parametric analysis based on two different mechanical models, both of them considering the tether mass and elasticity and an electric current generated at one end that interact with the Earth’s ionosphere. The magnetic field variation along the orbit is considered, giving raise to forced oscillations of the system around its equilibrium configuration.
Mesh Stiffness Variation Instabilities in Two-Stage Gear Systems
Authors: Lin Jian , Parker Robert G. 
Published: November 2020

Abstract
Mesh stiffness variation, the change in stiffness of meshing teeth as the number of teeth in contact changes, causes parametric instabilities and severe vibration in gear systems. The operating conditions leading to parametric instability are investigated for two-stage gear chains, including idler gear and countershaft configurations. Interactions between the stiffness variations at the two meshes are examined. Primary, secondary, and combination instabilities are studied. The effects of mesh stiffness parameters, including stiffness variation amplitudes, mesh frequencies, contact ratios, and mesh phasing, on these instabilities are analytically identified. For mesh stiffness variation with rectangular waveforms, simple design formulae are derived to control the instability regions by adjusting the contact ratios and mesh phasing. The analytical results are compared to numerical solutions.
Explanation of Appearance and Characteristics of Intermittency Chaos of the Impact Oscillator
Authors: Peterka František , Kotera Tadashi , Čipera Stanislav 
Published: November 2020

Abstract
Chaotic motion of an intermittency type of the impact oscillator appears near segments of saddle-node stability boundaries of subharmonic motions with two different impacts in motion period, which is n multiple (n ≥ 3) of excitation period. Chaotic motion arises due to an additional impact, which interrupts the process of instability. It is proved and shown by numerical simulations of the system motion. More detail characteristics of the intermittency chaos are evaluated. Described phenomena present unusual example, when transition cross special segments of saddle-node stability boundaries of subharmonic impact motions is reversible.
Topological Solitons in Non-Degenerate One-Component Chains: Part I — Analytical Study
Authors: Manevitch Leonid I. , Savin Alexander V. , Sigalov Grigori M. 
Published: November 2020

Abstract
For the first time, the possibility of existence of topological solitons in one-component chain with a non-degenerate potential of gradient type is proven. The existence and stability of the solitons is ensured by competing piecewise-parabolic nearest-neighbor and parabolic second-nearest-neighbor interactions. The solitons are shown to move at a unique velocity. Soliton propagation may constitute an elementary event of structural transformations in the chain.
Study of an Elastoplastic Model With an Infinite Number of Degrees of Freedom
Authors: Bastien Jérôme , Lamarque Claude-Henri , Schatzman Michelle 
Published: November 2020

Abstract
We deal with the dynamical behavior of continuous elasto-plastic model of Masing, consisting of infinite number of springs and dry-friction elements. Using theory of differential inclusions we provide existence and uniqueness result. Moreover, we prove that continuous model is the limit of the discrete Masing model when the number of degrees of freedom tends to infinity. Starting from known results of numerical analysis, we build an implicit Euler-like numerical scheme of order one.
Piezoceramic Springs for Structural Semi-Active Multi-Modal Vibration Control
Authors: Corr Lawrence R. , Clark William W. 
Published: November 2020

Abstract
The ideal of controlling the vibrations of a structure by using variable stiffness members has been around for over fifteen years. Two types of mechanical springs, Type I and II, have been devised with control laws to reduce the dynamic response of structures due to disturbances. By comparing the mechanical springs and their control laws to the novel real-time piezoceramic shunt switching techniques, it is clear that piezoceramic actuators can act similar to Type I and II mechanical springs. In this paper, piezoceramic actuators are used with three different shunt circuits (capacitance ladder, switching ground circuit, and switching resistor/inductor circuit) and are compared to their mechanical spring counterparts. A new type of spring, Type III, is introduced along with a new semi-active multi-modal control scheme for piezoceramic actuators. The new multi-modal control technique is used on a simple six degree of freedom numerical example.
Comparison of Robust Residual Vibration Suppression Capabilities of Conventional Digital Filters
Authors: Economou D. , Mavroidis C. , Antoniadis I. 
Published: November 2020

Abstract
Digital filters consist a quite effective robust residual vibration tool, when they are used for preconditioning any excitation function, prior to its application in a flexible system. Since a quite large number of conventional digital filters already exist, each one obtained by a different design procedure and resulting to different characteristics, a systematic comparison of their capabilities is performed. Critical design parameters are addressed, influencing the filter behavior in vibration suppression, such as the total delay introduced by the filter, the permitted residual vibration error, the robustness degree achieved and the necessary computational requirements in their implementation. It is shown, that although mere does not exist a single type of filter, simultaneously conforming to an optimal degree to all the design requirements, a large variety of conventional filters can be effectively used for the several individual residual vibration suppression requirements.
Radial Direction Position Control of a Disk Type Integrated Motor-Bearing System
Authors: Han Woo-Sup , Lee Chong-Won , Park Sung-Ho , Okada Yohji 
Published: November 2020

Abstract
An integrated disk type motor-bearing system having axial magnetic flux is newly invented and its design, analysis, and control methods are presented. Sinusoidal motoring currents to four symmetrically placed winding groups produce a torque, whereas control currents of the same magnitude but opposite signs added to the opposite winding groups create radial forces. The control currents are intended to break force symmetry, resulting in unbalanced radial forces. It is shown that the prototype integrated motor-bearing system built in the laboratory succeeds in stable radial direction control and operation of the rotor.
Active Wave Cancellation of the Axially Moving String
Authors: Tan Chin An , Ying Shenger 
Published: November 2020

Abstract
The active wave control of the linear, axially moving string with general boundary conditions is presented in this paper. Considerations of general boundary conditions are important from both practical and experimental viewpoints. The active control law is established by employing the idea of wave cancellation. An exact, closed-form expression for the transverse response of the controlled system, consisting of the flexible structure, the wave controller, and the sensing and actuation devices, is derived in the frequency domain. Two actuation forces, one upstream and one downstream of an excitation force, are applied. The proposed control law shows that all modes of the string are controlled and the vibration in the regions upstream and downstream of the control forces can be cancelled. However, these results are based on ideal conditions and the assumption of zero initial conditions at the non-fixed boundaries. Effects of non-zero boundary motions at the instant of application of the control forces are examined and the control is shown to be effective under these conditions. The stability and robustness of the control forces are improved by the introduction of a stabilization coefficient in the control law. The effectiveness, robustness and stability of the control forces are demonstrated by simulations and verified by experiments on axially moving belt drive and chain drive systems.
A Computer Algebra Approach for the Modeling and Design of Smart Piezoelectric Structures
Authors: Kugi Andreas , Schlacher Kurt 
Published: November 2020

Abstract
The field of applications for smart structures based on piezoelectric devices is manifold. An advantage of this technology is that one can construct spatially distributed devices. This fact requires special control techniques to use the additional freedom for the design of the overall system. The structures under consideration are composite beams and plates consisting of a large number of thin layers of laminae with and without piezoelectric properties that can be well described by Lagrangian systems. Furthermore, there exists a wide range of controller design methods. To apply this machinery, one has to derive the potentials and energy functions related to the piezoelectric structures, which is a laborious task for more complex structures. But this task can be perfectly performed by a computer algebra system. Therefore, this contribution deals with the application of the Lagrangian formalism to the modeling and design of smart piezoelectric structures, and the implementation of the proposed approach in a computer algebra system.
Nonlinear Dynamics of a Cantilever Beam Actuated by Piezoelectric Layers
Authors: Wolf K. , Gottlieb O. 
Published: November 2020

Abstract
The nonlinear equations of motion for a silicon cantilever beam, covered symmetrically by piezoelectric ZnO layers are derived for voltage excitation. Starting with the nonlinear description of the strain distribution in the beam for finite displacement, the Lagrangeian of the system is obtained from the electric enthalpy density. By application of Hamilton’s principle, the nonlinear equations of motion are consistently derived and truncated to third order for perturbation analysis. The evolution equations are obtained by the multiple scales method and periodic solutions to the equations of motion are determined and discussed with respect to the influence of geometric nonlinearities and nonlinear properties of the piezoelectric layer.
Self-Moving Cell Linear Motor Using Piezo Actuators
Authors: Kim Jaehwan , Lee Jinho 
Published: November 2020

Abstract
The concept of a new linear motor that uses piezo-stack actuator is demonstrated. The working principle is far different from the conventional inchworm motor. This motor is based on the self-moving cell concept. The linear motor has three cells and each cell is constructed with one piezo-stack actuator and a shell structure. A cell train is constructed by connecting these cells and the train is fitted into a giudeway with interference. By activating each cell in succession, the train can move along the guideway. The moving motion of the motor is tested. Since this linear motor uses piezo-stack actuator with unified clamping cell, there is possibility to produce fast speed, high resolution and large push force.
Simulation-Based Design of Hybrid Vibration Mounts
Authors: Su J. Hannsen 
Published: November 2020

Abstract
The simulation-based design (SBD) in this paper is a methodology that integrates and streamlines the design and analysis processes for engineering products. Its methodology is presented by starting from the method development to some specific designs of different hybrid vibration mounts. In particular, two hybrid mount designs such as the “Passive-Active Extensional” mounts, incorporating an extensional active component between a conventional mount and the jointed structure, and the “Passive-Active” mounts, adding inertial actuators to the attachment plate of a conventional mount, are considered in a realistic example to illustrate the application of SBD. It is demonstrated that the functionality and feasibility of many design alternatives and concepts can be realized by this methodology. Each design and evaluation time takes only a few minutes when this methodology is implemented in engineering software. Therefore, more optimal designs can be achieved in less time and at lower cost.
Optimization in the Simulation Based Design Environment
Authors: Kusmik W. Aldo 
Published: November 2020

Abstract
Simulation based design methodologies have the potential to streamline the development and continuous improvement of complex products by addressing three fundamental aspects of team-based product development initiatives: coordination, collaboration, and optimization. On-going research funded by the Office of Naval Research is seeking to augment its baseline simulation based design environment with enhanced system integration, visualization, and optimization capabilities that address these three aspects of the product development process. The inherent strengths of the existing software environment are being leveraged to support the development of these enhanced capabilities including Multi-Disciplinary Optimization methodologies that will enable the rapid convergence on high payoff system alternatives.
CVT Gear Noise in the Hybrid Car Drive Train
Authors: Maier Stefan K. , Pfeiffer Friedrich 
Published: November 2020

Abstract
The hybrid passenger car of the Technical University of Munich contains a complex i2-CVT-gearbox with one PIV-chain CVT-stage, six spur gears and internal clutches. This paper presents a method to access its noise emission and to identify important sources based on design parameters. A multibody system model of the gearbox and the entire drive train as set up on the testbed is built. Excitation mechanisms like impact and frictional forces between rocker pins of the chain and the discs of the CVT as well as toothing forces are modelled in detail by complex nonlinear stiffness functions. A method to calculate the A-rated equivalent continuous force level of the bearing forces, which is proportional to the sound is presented here. As it is based on a Fourier transform of the bearing force trajectories, the influence of excitation mechanisms on structural borne sound can be shown and confirmed by measurement.
Dynamics of Mechanisms With Slider Joints and Clearance
Authors: Marghitu Dan B. , Stoenescu Eleonor D. 
Published: November 2020

Abstract
In this study a planar mechanism with a rotating sliding joint is investigated. Periodic behavior is observed for zero clearance of the sliding joint. The sliding joint with clearance is modeled using a kinematic coefficient of restitution and a coefficient of friction. Nonlinear dynamics tools are applied to analyze the simulated data captured from the connecting rod of the mechanism. The stability of the motion is studied using the Lyapunov exponents. The largest Lyapunov exponents will be considered as a stability index for the chaotic behavior of the system with slider clearance. The chaotic behavior is studied for different clearances of the sliding joint and different angular velocities of the crank.