bluuebunny/crossref_metadata_2025_split huggingface dataset:
Damage Modeling in Honeycomb Panels for Tap Testing
Authors: Dayal Vinay , Mir Gohar M. , Hsu David K. 
Published: November 2021

Abstract
Effect of damage on Composite Honeycomb panel due to low speed impact is of significance. The result of such impact is damage such as crushing or buckling of the core, core to face de-bonding and local de-lamination of the plies. The damage, however, may be invisible to human eye but can result in significant degradation of stiffness and strength of Honeycomb structure. Of all the NDE techniques available, Tap Test seems to be the cheapest and most suited for the detection of damage in face-sheets, the face-sheet to core de bonding, and core damage. Instrumented Tap Testing with scanning capability makes it a very attractive NDE tool. This work is concerned with modeling the Tap Test on composite honeycomb panels by Finite Elements in both static and dynamic modes.
Interactive Finite Element model has been developed having option of creating multiple defects of varying size at desired location within the core material. Model is generated using Graphite/Epoxy quasi-isotropic laminate as face sheet material with Nomex paper core, simulating condition of crushed core. The model was analyzed by applying point load (equivalent force of the impacting projectile) at the node of concern. The defect is modeled as a gap in the core.
Samples were made having defects at different core height and were analyzed using Finite Element Methods (ANSYS) and by Tap Testing under same boundary conditions and loading. The sensitivity of FE model and Tap Test to damage location and size has been studied and the results are presented.
An Efficiency Study of Laser-Induced Thermoelastic Wave Generation in Layers
Authors: Wu Ji , Cetinkaya Cetin , Li Chen 
Published: November 2021

Abstract
The elastic wave generation and the efficiency of the thermal-to-mechanical energy conversion process of elastic wave generation by laser excitation are studied. A previously developed transfer matrix formulation [3, 4] is reviewed and the transient response in a silicon layer is computed by employing FFT. The transient thermal and mechanical response of a layer are considered, and the transient temperature, stress, acceleration and mechanical power are obtained under micro-second level excitation. The generation efficiency for the elastic wave components, which are utilized to evaluate the state of layered structures, is examined for a silicon layer. The results presented are useful in determining instrument specification, such as laser power, receiver dynamic range, and test set-up design.
Inspection of Concrete-Metal Rod Interface Using Guided Waves
Authors: Na Won-Bae , Kundu Tribikram , Ehsani Mohammad R. 
Published: November 2021

Abstract
The feasibility of detecting interface degradation and separation of steel rebars in concrete beams using Lamb waves is investigated in this paper. It is shown that Lamb waves can easily detect these defects. A special coupler between the steel rebar and ultrasonic transducers has been used to launch non-axisymmetric guided waves in the steel rebar. This investigation shows that the Lamb wave inspection technique is an efficient and effective tool for health monitoring of reinforced concrete structures because the Lamb wave can propagate a long distance along the reinforcing steel bars embedded in concrete as the guided wave and is sensitive to the interface debonding between the steel rebar and concrete.
Ultrasonic Guided Waves in Thin Orthotropic Layers: Exact and Approximate Analyses
Authors: Datta Subhendu K. , Mukdadi Osama 
Published: November 2021

Abstract
Exact and approximate analyses of ultrasonic guided wave propagation in thin orthotropic layers are presented in this work. Exact solutions to the equations governing the dependence of guided wave propagation speeds on the elastic constants characterizing the anisotropic properties of the layers are presented and compared with the predictions of first order approximate theories for extensional and flexural waves in thin plates. Comparison with available experimental results for dispersion of these waves in thin sheets of different types of papers leads to the confirmation or modification of the elastic constants and density reported for these papers. A particular focus of this study is the coupling of three types of guided waves (extensional (S), flexural (A), and shear-horizontal (SH)) due to anisotropy of the material. It is shown that there are significant changes in the dispersion characteristics of these modes at certain frequencies, which can be exploited to measure the in-plane elastic properties of thin layers. Another focus is to study the limitations of approximate results when compared with exact solutions for wave propagation in different directions. In general good agreements are found at low frequencies.
Review of Basic Models in Fire Dynamics
Authors: Kim Hyeong-Jin , Lilley David G. 
Published: November 2021

Abstract
The ultimate goal of this study is to improve scientific understanding of fire behavior leading to flashover in structural fires. This document summarizes important information in five topic areas: burning rates, radiant ignition, fire spread rates, ventilation limit imposed by size of opening, and flashover criteria.
These are the main components related to the scientific understanding of the fire growth and flashover problem involved in real-world structural fires. Within each topic area, there are four subsections dealing with background, theory, comments, and references. Main components of the study are to develop improved mathematical simulations so as to improve the accuracy of theoretical calculation and to develop and extend the range of knowledge and modeling capability so as to extend the range of available experimental data.
Investigation of Spectral Radiation Heat Transfer and NOx Emission in a Glass Furnace
Authors: Golchert B. , Zhou C. Q. , Chang S. L. , Petrick M. 
Published: November 2021

Abstract
A comprehensive radiation heat transfer model and a reduced NOx kinetics model were coupled with a computational fluid dynamics (CFD) code and then used to investigate the radiation heat transfer, pollutant formation and flow characteristics in a glass furnace. The radiation model solves the spectral radiative transport equation in the combustion space of emitting and absorbing media, i.e., CO2, H2O, and soot and emission/reflection from the furnace crown. The advanced numerical scheme for calculating the radiation heat transfer is extremely effective in conserving energy between radiation emission and absorption. A parametric study was conducted to investigate the impact of operating conditions on the furnace performance with emphasis on the investigation into the formation of NOx.
The Practical Application of CFD in the Design of Industrial Centrifugal Compressors
Authors: Sorokes James M. , Hutchinson Bradley R. 
Published: November 2021

Abstract
In the development of industrial turbomachinery, the aerodynamic designer is faced with many complex fluid flow problems. In the mid to late 1980’s, Computational Fluid Dynamics (CFD) software was developed to assist in the solution of these flow fields. Initially applied only by high end gas turbine or jet engine designers, these sophisticated tools eventually found their way to engineers at industrial turbomachinery manufacturers. However, it has only been in the last five to ten years that industrial users have begun to make more widespread use of CFD. There are a variety of reasons for this slow adoption.
Problem Diagnosis and Aerodynamic Improvement of a Field Pipeline Compressor
Authors: Liu Zheji , Hill D. Lee , Biba Yuri I. 
Published: November 2021

Abstract
An extensive investigation surrounding a performance shortfall of a pipeline compressor is presented. Regions of high aerodynamic loss are identified from an extensive flange-to-flange numerical investigation. Special attention is placed on understanding the impact of the interface model between the rotating and stationary components on the performance of each individual component and the whole machine. This process lead to the redesign of the radial inlet, the diffuser region, and the volute. Upon numerical validation of the proposed design changes, the components were manufactured and installed into the compressor that was already operating in the field. “Field” testing showed the new design to have a peak efficiency improvement of 4 points surpassing the contract guarantee.
An Experimental Setup for Measuring Unstable Thermo-Mechanical Behavior of a Shape Memory Alloy Wire
Authors: ladicola Mark A. , Shaw John A. 
Published: November 2021

Abstract
An experimental arrangement is demonstrated that overcomes some difficulties in thermo-mechanical testing of thin Shape Memory Alloy (SMA) wires under uniaxial tension. It is now well known that stress-induced transformations in some SMAs under uniaxial loading can lead to mechanical instabilities and propagating phase transformation fronts. Critical parameters, such as nucleation barriers are difficult to measure by conventional testing techniques and are often masked by unavoidable stress concentrations at grips. In addition, simultaneous full field measurements of localized deformation and temperature fields are difficult to obtain for different ambient conditions. The current scheme uses a temperature-controlled conduction block and a non-uniform temperature field induced by thermoelectric modules to uncover the underlying thermo-mechanical response of the wire. The approach also allows access for optical and infrared imaging of the specimen deformation and temperature fields.
Effect of Feedback Control on the Power Consumption of Induced-Strain Actuators
Authors: Chandrasekaran Sriram , Lindner Douglas K. , Leo Don 
Published: November 2021

Abstract
In this paper we study the closed loop power flow characteristics between a controlled piezoelectric actuator and a current controlled drive amplifier for two different structural control laws. We determine the real and reactive power flow through the structure and actuator into the amplifier when the structure is excited with a sinusoidal disturbance force under both control laws. The dependence of the real and reactive components of the power on the material properties of the actuator, structure and the configuration of the controller is presented. These real and reactive power estimates are useful for sizing the drive amplifier for the actuator.
A General Magneto-Elastic Model of Terfenol-D Particle Actuated Composite Materials
Authors: Armstrong William D. 
Published: November 2021

Abstract
A new theory is presented of the nonlinear multi-axial magneto-elastic behavior of magnetostrictive particle actuated composite materials. The analysis assumes a uniform external magnetic field is operating on a large number of well distributed, crystallographically and shape parallel ellipsoidal magnetostrictive particles encased in an elastic, nonmagnetic composite matrix. Comparisons between experimental and model magnetostriction results show that the model is able to provide a quantitatively correct dependence on particulate volume fraction and longitudinal stress and quantitatively accurate magnetostriction curves for both homogenous Terfenol-D rod and magnetically ordered Terfenol-D particulate actuated epoxy matrix composites over experimentally applied field ranges.
An Active-Passive Piezoelectric Vibration Absorber for Structural Control Under Harmonic Excitations With Time-Varying Frequency
Authors: Morgan Ronald A. , Wang K. W. 
Published: November 2021

Abstract
It has been shown that piezoelectric materials can be used as passive electromechanical vibration absorbers when shunted by electrical networks. Semi-active piezoelectric absorbers have also been proposed for suppressing harmonic excitations with varying frequency. However, these semi-active devices have limitations that restrict their applications. The design presented here is a high performance active-passive alternative to semi-active absorbers that uses a combination of a passive electrical circuit and active control actions. The active control consists of three parts: an adaptive inductor tuning action, a negative resistance action, and a coupling enhancement action. A formulation for the optimal tuning of the piezoelectric absorber inductance on a multiple degree of freedom (MDOF) structure is derived. The effectiveness of the proposed system is demonstrated experimentally on a system under a variable frequency excitation. Extensive parameter studies are also carried out to show that the proposed design offers superior performance and efficiency compared to other state-of-the-art control methods.
A New Twisting and Bending Coupled Piezoelectric Actuator Using Shaped Electrodes
Authors: Kwak Seung-Keon , Washington Gregory 
Published: November 2021

Abstract
In this research, a new twisting and bending coupled piezoelectric actuator based on the spatial aperture shading technique is introduced. The shaped electrode twisting actuator consists of two layers of PZT-5H (lead zirconate titanate) and one middle layer of steel shim. The directionally shaped electrode technique is applied to achieve the both twisting and bending motions of the actuator. The comparison of an analytical model, a numerical analysis, and actual experimental results for the actuator are given. The generalized functions are used to determine the discontinuous forcing function of the actuator in the analytical model. For the numerical analysis, the actuator is modeled utilizing a multi-layered integrated finite element model. The models show good agreement with experimental research.
Damage Detection Using Experimental Data Based Methods
Authors: Lestari W. , Hanagud S. 
Published: November 2021

Abstract
The objective of this work is to develop a damage detection algorithm, which is based on experimentally identified data and a mathematical relation between the damage information and the changes in structural dynamic characteristics. The relation is derived in the form of a differential equation, which relate the damage information, natural frequency changes, and the modes of the undamaged and damaged structure. The curvature mode is chosen in this method due to its sensitivity to the presence of the damage and its localized information. The detection algorithm enables one to locate the damages and to obtain the corresponding magnitudes simultaneously. For illustration of the methods numerical simulation on damaged beams were conducted. The damages were considered as point damages. Numerical simulation results are presented.
Semi-Active Damping of Ground Resonance in Helicopters Using Magnetorheological Dampers
Authors: Wereley Norman M. , Costes Nicolas 
Published: November 2021

Abstract
We will assess the capabilities of physically motivated MR dampers to mitigate ground resonance instability and control the damping level of rotor lag modes. The objectives of this research are threefold: (1) develop a methodology for the integration of the MR damper into a classic linear ground resonance analysis assuming an isotropic rotor hub (all dampers and blades similar) and an anisotropic rotor hub (due to lag damper dissimilarity due to damage, for example), (2) assess whether MR dampers can stabilize a rotor system that exhibits unstable ground resonance, (3) assess whether MR dampers can stabilize a rotor which exhibits unstable ground resonance behavior due to lag damper degradation or damage. The analyses developed in this study show that MR dampers are feasible for achieving these goals.
Vibration Control of Laminated Composite Plates Using Magnetostrictive Layers
Authors: Reddy J. N. , Krishnan S. 
Published: November 2021

Abstract
In the present study, a theoretical formulation of laminated composite plates with integrated smart material layers, used as sensors and actuators for the vibration suppression of laminated composite plates, is presented. The third-order shear deformation theory of Reddy and a simple negative velocity feed back control are used to actively control the dynamic response of the plate. The Navier (analytical) solutions are derived for simply supported boundary conditions and a displacement finite element model is developed for a general plate. The effects of material properties, lamination scheme, and placement of the smart material layer on vibration suppression are investigated.
Active Control of Nonlinear Dynamics of Crane Loads
Authors: Li Y.-Y. , Balachandran B. , Krishna K. V. 
Published: November 2021

Abstract
In order to suppress crane-load oscillations on ship vessels, a novel mechanism called a mechanical filter was introduced recently. This system is further numerically studied in the present effort. With the aid of active control, it is illustrated as to how the suppression bandwidth can be tailored and bifurcations in the response of the crane load can be eliminated from the considered range of disturbance parameters. Suppression of crane-load oscillations in the presence of aperiodic ship-roll motions is also addressed.
Performance Enhancement of an Autoparametric Vibration Absorber Using Multiple Pendulums
Authors: Vyas Ashwin , Bajaj Anil K. , Raman Arvind 
Published: November 2021

Abstract
This paper analyzes the dynamics of a resonantly excited single degree-of-freedom linear system coupled to an array of nonlinear autoparametric vibration absorbers (pendulums). The case of a 1:1:…:2 internal resonance between pendulums and the primary oscillator is studied. The method of averaging is used to obtain first-order approximations to the nonlinear response of the system. The stability and bifurcations of the equilibria of the averaged equations are computed. It is shown that the frequency interval of the unstable single-mode response, or the absorber bandwidth, can be enlarged substantially compared to that of a single pendulum absorber by adjusting individually the internal mistunings of the pendulums. Use of multiple pendulums is also shown to engender degenerate bifurcations as the coupled-mode response “switches” from one pendulum to the other with changing external excitation frequency. This results in a significant enhancement of the performance of autoparametric vibration absorbers.
Input Preshaping With Robust Internal–Loop Compensator for Residual Vibration Suppression of a Beam–Mass–Cart System
Authors: Park S. , Kim B. K. , Chung W. K. , Youm Y. 
Published: November 2021

Abstract
In this paper, vibration suppression of an elastic beam fixed on a moving cart and carrying a concentrated or moving mass is considered. An input preshaping method with RIC (Robust Internal–loop Compensator) is proposed to suppress single mode residual vibration and to get accurate positioning of the beam–mass–cart system. The performance of the proposed input preshaping method is compared with that by previous ones by both numerical simulations and experiments.
Using the proposed method, accurate PTP positioning of the moving mass without residual vibration is obtained experimentally by modifying the proposed input preshaping method. It is also able to suppress initial vibration of the beam–mass–cart system carrying a concentrated mass. Finally, the proposed input preshaping method is applied to the system to follow square trajectories of the moving mass without residual vibration.
Control of Higher-Order Modes in Ducts Using Arrays of Herschel-Quincke Waveguides
Authors: Hallez Raphaël F. , Smith Jerome P. , Burdisso Ricardo A. 
Published: November 2021

Abstract
The Herschel-Quincke (HQ) tube concept is well known for attenuation of plane-wave noise in ducts. However the HQ-tubes system can also be effectively applied to more complex duct sound fields due to higher-order modes. In this paper, an analytical technique is developed to model and predict the effects of HQ waveguides in three-dimensional ducts in which higher-order modes exist. The analytical technique involves modeling the waveguide-duct interfaces as finite piston sources that couple the acoustic field inside the main duct with the acoustic field within the HQ waveguides. The analytical model is used to provide insight into the attenuation mechanisms of the HQ waveguide arrays. The effects of the configuration and number of the HQ waveguides on the performance of the system are investigated. The analytical results are also validated on the inlet of a turbofan engine experimentally. The results demonstrate the potential of the HQ tube concept to reduce noise in ducts in many industrial applications where higher-order modes exist.
Design of LQ and LC Optimal Controllers for Plate Vibration
Authors: Fariborzi Bora 
Published: November 2021

Abstract
The energy based control strategy “Linear Coupling Control (LCC)” (1) is used for controlling free and forced vibrations in a simply supported plate. The control strategy is implemented by coupling a virtual second order linear system (controller) to an oscillatory plant and creating an energy exchange between the two systems (2). The energy transfer phenomena from the plant to the controller is maximized by coupling the appropriate states. Once the transfer of energy has taken place it is dissipated via linear damping. To provide a basis for comparing the results of the proposed control algorithm and the conventional control methods, the linear quadratic optimal control method also was implemented. To investigate the performance of the control method, a laminated simply supported plate and the controller are numerically simulated. This paper focuses on design issues and numerical simulation.
A Comparison of Two Actuators for a Semi-Active Helmholtz Resonator
Authors: Birdsong Charles B. , Radcliffe Clark J. 
Published: November 2021

Abstract
Two electro-mechanical actuators are examined for a semi-active Helmholtz resonator acoustic device. The device is used to reflect narrow band noise back to the source in an acoustic duct. The controller and actuator are used to tune the system on-line allowing optimum performance over a range of operating conditions. Actuator dynamics play an important role in the controller design and the operation of the device. Two variations of an electro-mechanical actuator are considered here. The first uses a dual voice coil speaker with local feedback compensation and the second uses the same speaker without the compensation. It is shown that both arrangements are effective but with competing advantages. The compensated actuator provides more control authority but adds considerable background noise while the uncompensated actuator provides less control authority but adds no background noise. The choice of actuator depends on the noise control objectives of the particular application.
Simulation of Geometric Imperfections of Deformable Assemblies in CAD/CAM
Authors: Sellakh Réda , Riviere Alain , Sellem Eric 
Published: November 2021

Abstract
The dimensioning and tolerancing model presented in this paper allows the functional tolerancing of a class of mechanical parts to be performed. This model is based on the use of the TTRS concept and relative positioning constraints. In addition, the paper presents some improvements in the modelling of the assembly process and describes a sensitivity analysis approach to identify the key characteristics of the assembly.