bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Draw Furnace Geometry on High Speed Optical Fiber Manufacturing
Authors: Cheng Xu , Jaluria Yogesh 
Published: November 2021

Abstract
The motivation of manufacturers to pursue higher productivity and low costs in the fabrication of optical fibers requires large diameter silica-based preforms drawn into fiber at very high speed. An optimal design of the draw furnace is particularly desirable to meet the need of high-volume production in the optical fiber industry. This paper investigates optical fiber drawing at high draw speeds in a cylindrincal graphite furnace. A conjugate problem involving the glass and the purge gases is considered. The transport in the two regions is coupled through the boundary conditions at the free glass surface. The zonal method is used to model the radiative heat transfer in the glass. The neck-down profile of the preform at steady state is determined by a force balance, using an iterative numerical scheme. Thermally induced defects are also considered. To emphasize the effects of draw furnace geometry, the diameters of the preform and the fiber are kept fixed at 5 cm and 125 μm, respectively. The length and the diameter of the furnace are changed. For the purposes of comparison, a wide domain of draw speeds, ranging from 5 m/s to 20 m/s, is considered, and the form of the temperature distribution at the furnace surface is kept unchanged. The dependence of the preform/fiber characteristics, such as neckdown profile, velocity distribution and lag, temperature distribution and lag, heat transfer coefficent, defect concentration, and draw tension, on the furnace geometry is determined. Based on these numerical results, an optimal design of the draw furnace can be developed.
Performance Based Evaluation of Bridge Substructure in North Mississippi Using Nonlinear FEM and Field Vibration Measurement
Authors: Mullen Chris L. , Tuladhar Prabin R. 
Published: November 2021

Abstract
Discussion of a Performance - Based Engineering evaluation procedure for an existing interstate highway bridge in north Mississippi. The bridge is in a highly trafficked location near the Memphis Metropolitan area and is reflective of modern design practices in Mississippi.
Results are presented of nonlinear damage response and displacement ductility performance of the reinforced concrete bents and their foundations predicted using static finite element (FE) computations. The model considers the composite action of the concrete and the reinforcing steel materials under axial force, shear, torsion and flexure.
The performance-based evaluation includes three-dimensional computational simulations of the nonlinear bridge system, including substructures and superstructure. The response spectrum dynamic analysis method will also be carried out on the linear elastic three-dimensional model to predict the linear elastic behavior.
Field vibration measurements, including ambient and hammer-impact, were performed to calibrate the models. The computed transfer functions are currently being evaluated to correlate vibration measurements and the Finite element models.
Numerical Evaluation of Advanced Multi-Stage FCC Units
Authors: Chang S. L. , Zhou C. Q. , Lottes S. A. , Petrick M. 
Published: November 2021

Abstract
Conceptual multi-stage fluid catalytic cracking (FCC) units that use several short risers are considered by some refining industries to enhance product yields and product selectivity. A validated computational fluid dynamic (CFD) code was used to evaluate the concept. The code solves conservation equations of FCC flow properties for three phases: gaseous species, oil droplets, and catalyst particles. Phenomenological models were developed to characterize multi-phase interactions, including interfacial drag and heat transfer, droplet vaporization, cracking reactions, and flow turbulence. Parametric and optimization studies were performed to evaluate the impacts of operation/design parameters on the product yields of the conceptual advanced FCC units. The results showed that promising product yields and selectively could be achieved by proper design of stage arrangements and operation parameters.
Introducing the Carangithopter: A Small Piezoelectrically Actuated Swimming Vehicle
Authors: Borgen Michael , Washington Gregory , Kinzel Gary 
Published: November 2021

Abstract
A new type of miniature swimming vehicle is discussed in this study. Propulsion is developed through a posteriorly mounted fin that laterally oscillates in a fish-like manner. The fin is driven by a kinematic mechanism, which is in turn actuated by two high-deflection, curved-beam piezoelectric actuators. Analytical theories relating to individual components of this multidisciplinary system are covered, including discussions of kinematics and fin propulsion. A summary of the generation of static and dynamic actuator models is presented. The physical evolution of an actual swimming vehicle is discussed through the positive and negative aspects of several design iterations. The current vehicle status is presented in detail in terms of its physical design, operation, and controls and is evaluated in terms of speed and maneuverability.
Model Based Simulation of the Active Damping of a Cantilever Plate and Redistribution of Stresses
Authors: Hanagud Sathya V. , Roberts Patrick J. 
Published: November 2021

Abstract
In most structures, fatigue critical areas are associated with regions of high stresses. Sometimes, passive stiffening of structures can displace these high stress regions. Thus, for most applications, active vibration control is preferred. However, the question of whether an active vibration control scheme involving a set of actuators will reduce stresses in the whole structure or create high stress areas in the vicinity of the actuators arises. In previous works, this question has been addressed for cantilever beams which showed that the stresses are reduced by approximately the same order of magnitude as the reduction in vibrations. However, many aerospace structures are constructed of thin walled components whose response to vibration reduction can be very different than that of beams. In this paper, the stresses induced by an active vibration control system, based on the use of an offset piezoceramic stack actuator with acceleration feedback control, are investigated in a plate structure. A 3-D finite element simulation of the closed loop active vibration control system is developed and both the closed loop stresses and vibration amplitude reductions are studied.
State-Switched Absorber for Vibration Control of Point-Excited Beams
Authors: Cunefare Kenneth A. 
Published: November 2021

Abstract
A system that has the capability to make instantaneous changes in its mass, stiffness, or damping may be termed a state-switchable dynamical system. Such a system will display different dynamical responses dependent upon its current state. State-switchable stiffness may be practically obtained through the control of the termination impedance of piezoelectric stiffness elements. If such a switchable stiffness element is incorporated as part of the spring element of a vibration absorber, the change in stiffness causes a change in the resonance frequencies of the system, thereby instantaneously ‘retuning’ the state-switched absorber to a new frequency. In between state switches, the operation of such a device is passive, being fundamentally a passive vibration absorber. This concept has improved performance over classical passive vibration absorbers or dampers, particularly for disturbances with multiple spectral components. This paper considers the application of such a device for the purpose of vibration control on beams subjected to harmonic point-force excitation.
Stability of a Class of Piezoelectric State-Switching Methods
Authors: Kurdila Andrew J. , Clark William W. , Wang Weijian , McDaniel Dwayne E. 
Published: November 2021

Abstract
Experimental and anecdotal evidences have shown that state-switched control strategies for piezoelectric actuators can be advantageous. However, most discussions of the stability of these systems has relied on heuristic, or physically motivated, arguments. In this paper, we show that recent open-circuit/short-circuit state-switching control laws can be viewed as hybrid dynamical systems of Witsenhausen type. Within this framework, the closed-loop stability of OC/SC switching is rigorously established using the method of multiple Lyapunov functions.
Weak Noise Expansion of Moment Lyapunov Exponents of a Two-Dimensional System Under Bounded Noise Excitation
Authors: Xie Wei-Chau 
Published: November 2021

Abstract
The moment Lyapunov exponents of a two-dimensional system under bounded noise parametric excitation are studied in this paper. The method of regular perturbation is applied to obtain weak noise expansions of the moment Lyapunov exponent, Lyapunov exponent, and stability index in terms of the small fluctuation parameter.
The Quadratically-Damped Mathieu Equation and Its Application to Submarine Dynamics
Authors: Rand Richard H. , Ramani Deepak V. , Keith William L. , Cipolla Kimberly M. 
Published: November 2021

Abstract
This work is motivated by naval use of passive towed sonar arrays of hydrophones. We consider the simplest model of a towed mass. The mass is considered to move only in a horizontal direction x perpendicular to the tow direction. The tension in the tow cable is expected to be nonconstant due to turbulence, and is modeled by a sinusoidal forcing function. The resulting differential equations are analyzed for linear stability and nonlinear dynamical effects. In particular we study the nonlinear dynamics of the ODE: x ¨ + ( δ + ϵ cos t ) x + x ˙ | x ˙ | = 0
Adaptive Noise Isolation in Finite Ducts
Authors: Li Yugang , Malatpure Aniket , Rahn Christopher D. , Dawson Darren M. 
Published: November 2021

Abstract
Noise from jet engines, vehicle exhaust systems, and heating, ventilation, and air conditioning systems often involves planar acoustic wave propagation through finite ducts. This paper introduces controllers that use a loudspeaker actuator and two microphone pressure sensors to adaptively decouple adjacent ducts, thereby isolating a quiet duct from bounded disturbances in an adjacent noisy duct. The system model includes a one dimensional displacement-based partial differential equation for planar noise propagation in the two ducts and an ordinary differential equation for the speaker dynamics. Based on Lyapunov theory, Exact Model Knowledge and adaptive isolation controllers exponentially and asymptotically regulate the controlled duct from bounded disturbances in the uncontrolled duct, respectively, while ensuring bounded uncontrolled duct response and control voltage.
In-Situ Measurement and Monitoring of Fiber Preform Permeability for Liquid Composite Molding
Authors: Liang Zhiyong , Zhang Chuck , Wang Ben , Shih Chiang 
Published: November 2021

Abstract
In a liquid composite molding (LCM) process such as resin transfer molding (RTM), quality control depends on an in-situ permeability profile of the fibrous preform taken just before resin injection. However, the conventional permeability measurement method, which uses liquid (oil or resin) as its working fluid, only measures the average preform permeability in an off-line mode. It cannot be used to create an in-situ permeability profile because of fiber pollution, and cannot be used to reveal local permeability variations of preform. This study develops a new permeability characterization method that uses gas flow and pressure profiles to measure preform permeability variation in a closed mold assembly. This method is based upon two research findings: (1) that the air permeability of a preform can be obtained through measuring the pressure profile of gas flow, and (2) that resin permeability is highly correlated with air permeability for the same fiber preform. In this paper, the validity of this method is discussed. Experimental results of gas permeability measurement with defective and defect-free preforms are presented, and quantitative models for correlation of gas permeability versus pressure profile and of gas permeability versus resin permeability are also provided. Finally, the efficacy of the proposed method is illustrated through experimental results.
Representation of Heterogeneous Objects in ISO 10303 (STEP)
Authors: Patil Lalit , Dutta Debasish , Bhatt A. D. , Jurrens K. , Lyons K. , Pratt M. J. , Sriram R. D. 
Published: November 2021

Abstract
Solid modeling of objects forms an important task in design and manufacturing. Recent developments in the field of layered manufacturing have shown potential for the physical realization of heterogeneous (multi-material) objects. Thus, there is a need to represent material information as an integral part of the CAD model data. Information models for the representation of product data are being developed as an international standard called STEP (ISO 10303). However, the current application protocols focus on the representation of homogeneous objects only. This paper proposes an information model to represent heterogeneous objects using the information modeling methodology developed for ISO 10303. This will help in providing a uniform base in the development of heterogeneous solid modeling systems. It will also equip the solid modeler with the ability to integrate with other applications and process planning in the domain of layered manufacturing.
Formulae to Size Axisymmetric Heat Spreaders Above Dielectric Layers
Authors: Hodes Marc 
Published: November 2021

Abstract
The thermal resistance of requisite thin dielectric layers between high power dissipating devices and thermal ground, i.e., the base of a heat sink, is substantial. Thus power devices are frequently mounted on a heat spreader attached to the dielectric layer to reduce this thermal resistance. This paper provides analytically-derived formulae and accompanying dimensionless plots for the thermal resistance between the power device/heat spreader interface and thermal ground as a function of the relevant dimensionless geometric and thermal parameters for the axisymmetric and one-dimensional Cartesian geometries. These formulae/plots can be used to properly size the thickness and footprint of heat spreaders above dielectric layers. The utility of the results is demonstrated by an example.
Optimal Blank Design for the Drawings of Arbitrary Shapes by the Sensitivity Method
Authors: Shim H. B. , Son K. C. 
Published: November 2021

Abstract
The sensitivity method in order to find initial blank shapes which result in desired shapes after deformation has been used in this study.. By assuming the final deformation shape be the drawn cup with uniform trimming allowance at the flange, the corresponding initial blank which gives final shape after deformation has been found. With the aid of a well-known dynamic explicit analysis code PAM-STAMP, shape sensitivity has been obtained. To get the shape sensitivity numerically, a couple of deformation processes have been analyzed. Drawings of trapezoidal cup, oil pan, and Audi front door panel, the benchmark test problem of Numisheet ’99 have been chosen as the examples. At every case the optimal blank shape has been obtained only a few times of modification without predetermined deformation path. With the predicted optimal blank, both computer simulation and experiment are performed. Excellent agreements are recognized between simulation and experiment at every case. Through the investigation the sensitivity method is found to be very effective in the arbitrary shaped drawing process design.
Effective Models for Prediction of Springback in Flanging
Authors: Song Nan , Qian Dong , Cao Jian , Liu Wing Kam , Viswanathan Vikram , Li Shaofan 
Published: November 2021

Abstract
A study on the prediction of springback angle is presented, with focus on the straight flanging operation. The objective is to evaluate the reliability of different ways of prediction. An experiment of straight flanging operation is conducted. Major prediction approaches such as analytical model, numerical simulation using Finite Element Method (FEM) and Meshfree Method are discussed. A set of sample problems is computed and comparisons are made with the experiment. The numerical analysis shows that the prediction from the 3D meshfree contact code matches well with the data from FEM 2d solid model. A material property described by the kinematic hardening law gives a better prediction of springback than the isotropic hardening law.
Two Dimensional Plane Strain Modeling of Tube Hydroforming
Authors: Kridli G. T. , Bao L. , Mallick P. K. 
Published: November 2021

Abstract
The tube hydroforming process has been used in industry for several years to produce components such as exhaust manifolds. Recent advances in forming machines and machine control systems have allowed for the introduction and the implementation of the process to produce several automotive components, which were originally produced by the stamping process. Components such as side rails, engine cradles, space frames, and several others can be economically produced by tube hydroforming. The process involves forming a straight or a pre-bent tube into a die cavity using internal hydraulic pressure, which may be coupled with controlled axial feeding of the tube. One of the remaining challenges facing product and process engineers in designing hydroformed parts is the lack of an extensive knowledge base of the process. This includes a full understanding of the process mechanics and the effects of the material properties on the quality of the hydroformed product.
This paper reports on the results of two dimensional plane strain finite element models of the tube hydroforming process, which were conducted using the commercial finite element code ABAQUS/Standard. The objective of the study is to examine the effects of material properties, die geometry, and frictional characteristics on the selection of the hydroforming process parameters. The paper discusses the effects of the strain-hardening exponent, friction coefficient at the die-workpiece interface, initial tube wall thickness, and die corner radii on the thickness distribution of the hydroformed tube.
Corner Fill Modeling of Tube Hydroforming
Authors: Chen J. Y. , Xia Z. C. , Tang S. C. 
Published: November 2021

Abstract
Hydroforming process provides important advantages for automotive structural components over conventional stamp-and-weld parts, but it also brings unique challenges in process design. This paper attempts to obtain fundamental understanding of the process through corner fill modeling. A round tube is pressurized to expand into a square box with tight radius in the numerical experiment. Several parameters are identified and investigated during the process, namely, the internal pressure, end feed, and the lubricant. Their effects on the deformation profiles are presented, and their importance in process design is discussed. The established design guidelines from the study can be a valuable tool for hydroforming process engineers and part designers.
Generation of Cyclic Stress-Strain Curves for Sheet Metals
Authors: Zhao K. M. , Lee J. K. 
Published: November 2021

Abstract
The main objective of this paper is to generate cyclic stress-strain curves for sheet metals so that the springback can be simulated accurately. Material parameters are identified by an inverse method within a selected constitutive model that represents the hardening behavior of materials subjected to a cyclic loading.
Three-point bending tests are conducted on sheet steels (mild steel and high strength steel). Punch stroke, punch load, bending strain and bending angle are measured directly during the tests. Bending moments are then computed from these measured data. Bending moments are also calculated based on a constitutive model. Normal anisotropy and nonlinear isotropic/kinematic hardening are considered. Material parameters are identified by minimizing the normalized error between two bending moments. Micro genetic algorithm is used in the optimization procedure. Stress-strain curves are generated with the material parameters found in this way, which can be used with other plastic models.
Spatial Free Plastic Forming of Slender Parts: Machine Design, Forming Limits, and Application
Authors: Thalmair M. , Lippmann H. , Reigl M. 
Published: November 2021

Abstract
Free plastic forming of a slender part means that an initially straight bar, clamped at its both ends, is bent and twisted by an appropriate motion of the end supports only. Emphasis is attached on the computer controlled, precise forming of work-pieces with prescribed shape. In this paper the design of an appropriate forming machine at the laboratory scale will be presented. Moreover the forming limits, due to re-plastification of already completed sections of the part, will be illustrated geometrically using one or two “cylinders of admissibility”. Finally the method will be demonstrated by means of actually formed parts.
Stress-Based Forming Limits in Sheet Metal Forming
Authors: Stoughton Thomas B. 
Published: November 2021

Abstract
A strain-based forming limit criterion is widely used throughout the sheet metal forming industry to gauge the stability of the deformed material with respect to the development of a localized neck prior to fracture. This criterion is strictly valid only when the strain path is linear throughout the deformation process. There is significant data that shows a strong and complex dependence of the limit criterion on the strain path. Unfortunately, the strain path is never linear in secondary forming and hydro-forming processes. Furthermore, the path is often found to be non-linear in localized critical areas in the first draw die. Therefore, the conventional practice of using a path-independent strain-based forming limit criterion often leads to erroneous assessments of forming severity. Recently it has been reported that a stress-based forming limit criterion appears to exhibit no strain-path dependencies. Subsequently, it has been suggested that this effect is not real, but is due to the saturation of the stress-strain relation. This paper will review and compare the strain-based and stress-based forming limit criteria, looking at a number of factors that are involved in the definition of the stress-based forming limit, including the role of the stress-strain relation.
Wrinkling Limit in Tube Bending
Authors: Wang Xi , Cao Jian 
Published: November 2021

Abstract
Thin-walled tube bending has found many of its applications in the automobile and aerospace industries. This paper presents an energy approach to provide the minimum bending radius, which does not yield wrinkling in the bending process, as a function of tube and tooling geometry and material properties. A doubly-curved sheet model is established following the deformation theory. This approach provides a predictive tool in designing/optimizing the tooling parameters in the tube bending.
FEM-Assisted Fuzzy Adaptive Blank Holder Control Approach for Sheet Stamping Process
Authors: Koyama Hiroshi , Manabe Ken-ichi , Yoshihara Shoichiro 
Published: November 2021

Abstract
To apply the database-oriented process control design concept to intelligent stamping processes of various shape products, the extension of the concept was required. The application of FEM simulation for production of the “ideal curve”, which plays an important role in the system, was proposed. The fuzzy adaptive controlled variable blank holder force (BHF) circular-cup deep-drawing system with the new ideal curve was developed. Through the implementation of the system for cup height improvement, the availability of the concept is confirmed. As a result, the potential application of the concept to the stamping processes of various shapes is suggested. In addition, using the experimental results, the influence of the BHF history on the thickness reduction behavior is investigated. An algorithm for cup wall thickness uniformity based on the BHF historical effects is proposed and the feasibility of the algorithm is verified.