bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modeling and Control of a 2-Dimensional Overhead Crane
Authors: Lee Ho-Hoon 
Published: March 2022

Abstract
In this paper, a trolley-axis-based swing angle description is proposed for a 2-dimensional overhead crane, and then a new nonlinear dynamic model for the crane is derived based on the proposed swing angle description. The dynamic model is equivalent to that for 3-link flexible robots having only the first flexible mode. Furthermore, when the model is linearized around the vertical stable equilibrium, it becomes decoupled and symmetric with respect to the travel and traverse axes of the crane. From this result, a decoupled feedback control method is proposed based on the linearized model via the loop shaping and the root locus methods. Theoretical and experimental results show that the proposed control method guarantees not only fast damping of load swing but also accurate control of trolley position with sufficient damping for the 2-dimensional motion of the crane.
A Simulation Study of the Workspace and Dexterity of a Stewart Platform Based Machine Tool
Authors: Saxena Vivek , Liu Dongming , Daniel Cecil M. , Sutherland John W. 
Published: March 2022

Abstract
A machine tool based on a Stewart platform structure has many inherent advantages. These include: six degree of freedom, low mass and high structural rigidity. However, a good understanding of the kinematics of the structure is required for successful implementation of such a machine tool. Two attributes of a Stewart platform based machine tool — the workspace and dexterity are investigated in this work. The workspace is analyzed using a point discretization method in which discrete points are checked by the inverse kinematic solution of the Stewart Platform. The workspace thus obtained is presented graphically for various positions and orientations of the end effector. The dexterity of the workspace is studied by calculating the condition number for each discrete point. The results of the workspace and dexterity study are explained. The plots of workspace and dexterity may be used in the design stage for efficient utilization of the available workspace for a given machining operation.
Modeling of a 5-Speed Automatic Transmission for Shift-Quality Control
Authors: Lee Je-Kee , Peng Huei , Park Yeong-Il 
Published: March 2022

Abstract
The shift quality control of a 5-speed automatic transmission (A/T) is studied in this paper. The major technical challenge arises from the fact that the gear ratios of both gearsets may have to change simultaneously, which requires precise coordination. For the particular A/T studied in this paper, this “swap shift” occurs during second to third gear upshift. The dynamic equations during this 2-to-3 upshift are derived using the lever analogy technique. A nonlinear programming problem is then formulated to compute the optimal shift control algorithm, which strikes a balance between smoothness and shift time.
Vehicle Lateral Control on Automated Highways: A Backstepping Approach
Authors: Chen Chieh , Tomizuka Masayoshi 
Published: March 2022

Abstract
A backstepping controller is designed for lateral guidance of the passenger car in automated highway systems. In this design, the vehicle lateral tracking error is viewed as the output regulated by the relative yaw angle of the car with respect to the road centerline, and the relative yaw angle is controlled by the vehicle’s front wheel steering angle. The closed loop performance of lateral and yaw dynamics can be specified and guaranteed simultaneously in this approach. A smooth road model is used in calculating the feedforward part of the steering command. Nonlinear position feedback, which acts as low gain control at small tracking errors and high gain control at larger tracking errors, is introduced to compromise between passenger ride comfort and tracking accuracy. Simulation results conducted on the complex vehicle model show the effectiveness of the backstepping design approach.
Robust and Gain Scheduled H∞ Controllers for Lateral Guidance of Passenger Vehicles in AHS
Authors: Hingwe Pushkar , Tomizuka Masayoshi 
Published: March 2022

Abstract
This paper presents two lateral control designs for passenger vehicles in the Automated Highway System (AHS). The control designs are a natural combination of input-output linearization technique and the H∞ control design techniques. Input-output linearization in the context of steering angle as the input and lateral error at a certain point on the vehicle as the output is the first design step. Even though this form is amenable to robust control techniques such as the Sliding Mode Control, there is insufficient, damping of the yaw dynamics, especially at high longitudinal velocities. The damping of the yaw dynamics is improved by adding an outer feed back loop based on the H∞ control techniques.
A Hybrid Semiactive Control for Secondary Suspension Applications
Authors: Ahmadian Mehdi 
Published: March 2022

Abstract
The performance of semiactive “skyhook” dampers for secondary suspensions is compared with passive dampers, using a single suspension model. The simulation results indicate that, compared to passive suspensions, semiactive skyhook dampers provide a more favorable control of the dynamic resonance without decreasing the isolation effectiveness of the suspension. Further, it is shown that skyhook dampers provide a better control of one body at the expense of less control of the other body. An alternative semiactive control policy, called “hybrid control,” is introduced to provide a better control of both the bodies that the suspension connects together. The hybrid control can be implemented using the same hardware commonly used for the existing semiactive dampers.
On Ultrasound High Frequency Linear Viscoelasticity
Authors: Giordano Michele , Astarita Gianni 
Published: March 2022

Abstract
An elementary analysis of wave propagation in viscoelastic materials is presented. Data on linear viscoelasticity obtained with ultrasound high frequency wave excitation are reviewed in this light. It is concluded that such data seem to indicate that a), propagation of very high frequency waves is dominated by a viscous mechanism; and b), values of the complex propagation modulus M* do not lie on any reasonable extrapolation of the mechanical G* data. Possible interpretations of these results are discussed.
Boundary Conditions for Electro-Magneto-Hydrodynamics
Authors: Dulikravich George S. , Jing Youhao 
Published: March 2022

Abstract
A general mathematical model of characteristic and non-reflecting boundary conditions for a system of partial differential equations governing unified Electro-Magneto-Hydrodynamic (EMHD) flows is developed. The novelty of this work is that it includes effects of linear polarization and magnetization of the media. A formulation using characteristic wave relations at the boundaries is derived for the extended Maxwell’s equations and the extended Navier-Stokes equations so that it can be used to specify inflow and outflow free boundary conditions. The emphasis is on using recent theoretical results on well-posedness of boundary conditions for standard Navier-Stokes and Maxwell’s equations to construct a systematic method for specifying the physical and numerical boundary conditions for electro-magneto-hydrodynamics. The formulation is fully three-dimensional and suitable for direct numerical implementation. The results show strong influence of electric and magnetic fields on fluid flow characteristics.
Vibration-Assisted Liquid Composite Molding: Practical and Numerical Simulation
Authors: Ayorinde Emmanuel O. , Gibson Ronald F. , Deng Feihua , Baig Bakhtiar 
Published: March 2022

Abstract
Vibration assistance in the process of liquid composite molding (LCM), a relatively new concept, is investigated in this paper. A non-Newtonian resin simulator fluid (1% polyacrylamide/water solution) is injected with vibration assistance into a simulator mold, with pre-placed actual (industrial) pre-form. Mold filling under various conditions is investigated.
An analytical model based on the control volume finite element representation is constructed for the process. A comparison of the experimental and computational results showed good agreement. Effects of the presence of the preform, the damping of the input vibration in the mold space, and how it is affected by various parameters are investigated.
Nondestructive Elastic Property Characterization of IC Encapsulants
Authors: Canumalla Sridhar , Oravecz Michael G. 
Published: March 2022

Abstract
The elastic properties of IC packaging materials (molding compounds and underfills) are measured nondestructively, over a microscopic area, in this study. The first application involves determining the engineering moduli of molding compounds (MP8000CH, MP190ML, 6300HA and 7320) from a nondestructive measurement of ultrasonic velocities. The second application involves the characterization of processing flaws in flip-chip packages to a) unambiguously identify delaminations (or voids) from resin rich areas, and b) quantitatively estimate the relative change in filler content. Concomitant changes in elastic properties of the underfill are also determined. Regions of filler segregation, exhibiting a lower impedance of about 3.9 MRayl (26% lower) are estimated to have a Young’s modulus of 7 GPa (50% lower) and a CTE of 41 x 10-6/°C (57% higher than the base material). Techniques presented in this paper have potential application in advanced process control, yield management and in analysis of package reliability.
Adhesion and Reliability of Polymer/Inorganic Interfaces in Microelectronic Applications
Authors: Snodgrass J. M. , Kook S.-Y. , Kirtikar A. , Dauskardt R. H. 
Published: March 2022

Abstract
The reliability of microelectronic components is profoundly influenced by the interfacial fracture resistance (adhesion) and resistance to progressive debonding of interfaces. In this study we examine the interfacial fracture properties of representative polymer interfaces commonly found in microelectronic applications. Specifically, interface fracture mechanics techniques are described to characterize adhesion and progressive debonding behavior of a polymer/metal interface under cyclic fatigue loading. Cyclic fatigue debond-growth rates were measured from ∼10−10 to 10−6 m/cycle and found to display a power-law dependence on the applied strain energy release rate range, ΔG. Fracture toughness test results show that the interfaces typically exhibit resistance-curve behavior, with a plateau interface fracture resistance, Gss, strongly dependent on the interface morphology and the thickness of the polymer layer. The effect of a chemical adhesion promoter on the fracture energy of a polymer/silicon interface was also characterized. Micromechanisms controlling interfacial adhesion and progressive debonding are discussed in terms of the prevailing deformation mechanisms and related to interface structure and morphology.
Die Strength Evaluation in the Presence of Edge Cracks
Authors: Leung Betty , Guo Yifan , Sarihan Vijay 
Published: March 2022

Abstract
Achieving a reliable package requires ensuring the reliability of each of its components and their interconnections. In practice, die strength is adversely affected when dies undergo various manufacturing processes. High stresses are also induced when dies are subject to conditions such as testing, handling, and operation. Die reliability depends on processed die strength under possible stress conditions. Existing information on the die strength is limited to what is known about perfect, unprocessed silicon. The accurate measure of the strength of processed dies is achieved through evaluation of the real component. This work focuses on the comparative analysis of test methodologies and the effects of processing. Characterization of actual die defects dies, primarily due to processing, is followed by experimentation utilizing a system designed at Motorola’s AISL specifically for the testing of small dies. Failure analysis of fractured dies reveals the effects of different test methods and the roots of die fracture. Coupling the experimental data from this work with predicted stress results produced through finite element analysis, a measure of the adequacy of a die’s strength for a given package can be made, providing valuable information for purposes of package reliability and enhancement.
Strain Localization in Single Crystals: Thermodynamic Consideration
Authors: Le Khanh Chau 
Published: March 2022

Abstract
This paper presents a model describing strain localization in single crystals. Constitutive relations for slip systems axe proposed within the framework of thermodynamics. A generalized Schmid law is formulated in terms of the Eshelby stress tensor. The strain localization is found to be possible when the hardening rate for active slip systems has fallen to a certain critical positive value hcr. The latter is determined for double active slip systems. A comparison with corresponding results available in the literature is provided.
Nondestructive Evaluation of Fiberglass Reinforced Plastic Subjected to Localized Heat Damage, Using Acoustic Emission
Authors: Nayeb-Hashemi H. , Kisnomo P. , Saniei N. 
Published: March 2022

Abstract
Fiberglass reinforced composites are extensively used in electronic and aerospace applications due to their high specific strength. In these applications, they are often subjected to localized heat damage due to various sources such as electronic over heating, electric arching, and laser beams. In order to ensure their reliability, it is important to predict their residual properties using nondestructive evaluation techniques.
Unidirectional fiberglass composite specimens were manufactured using three layers of a fiber glass prepreg. Some of the specimens were subjected to a localized heat damage using a heated copper tip with a diameter of 12.5 mm at 360° C and other specimens were subjected to a laser beam operated at 0.64 Watts/mm2 for various exposure time. In addition, the number of laser damaged spots varied among similar specimens. The specimens were then subjected to tension tests while acoustic emission activities of specimens were collected.
The AE activity of all specimens showed three distinct regions. An early activity, followed by a relatively dormant activity period and a high exponential activity before final failure. The period of the dormant activity was independent of the contact heat duration of less than 15 minutes. However, the dormant period for the laser damaged specimens was a function of the number of laser damaged spots. The majority of the early activities for all specimens were related to mechanisms other than fiber fracture. The activity in the dormant period for contact heat damage was mainly controlled by the fiber fracture, while for the undamaged and laser damaged specimens was by the interfacial failure. This could be justified since laser damaged specimens contained numerous damaged fibers leading to a significant interfacial shear stress. The failure modes of specimens further supported this conclusion.
The state of the damage in the composite was predicted using the AE-stress delay concept.
On Dynamic Modeling of Multi-Link Spatial Manipulators With Flexible Links and Joints
Authors: Farid Mehrdad , Lukasiewicz Stanislaw A. 
Published: March 2022

Abstract
A redundant Lagrangian/finite element approach is proposed to model the dynamics of lightweight spatial manipulators with both flexible links and joints. The links are assumed to be deformable due to bending and torsion. The elastic deformations of each link are expressed in its tangential (clamped free) local floating frame. The constraint equations due to the connectivity of the links are added to the equations of motion of the system by using Lagrange multipliers. The resulting mixed set of nonlinear differential equations and algebraic equations (DAEs) is solved numerically to predict the dynamic behavior of the system. The dynamic model derived here is free from the assumption of a nominal motion and takes into account not only the coupling effects between the rigid body motion and the elastic deformations of the links, but also the interaction between flexible links and actuated flexible joints.
Coupled Oscillations of Spherical Gas Bubbles
Authors: Jang Young J. , King Melvin E. 
Published: March 2022

Abstract
The dynamics of several (two, three and four) interacting spherical gas bubbles are investigated using the method of multiple scale. Numerical solutions for the steady-state amplitudes and phases of systems of two and four bubbles are presented. An interesting phenomenon observed is that of nonlinear localization, wherein vibrational energy becomes spatially localized to a single bubble (strong localization) or to a subset of bubbles (weak localization). Moreover, it is shown that the spatially extended motion (wherein all bubbles oscillate with identical amplitudes and phases, which one would obtain based upon a linearized analysis) is unstable, and thus not physically realizable, for certain separation distances.
A Nonlinear Wear Model
Authors: Nielsen Jakob Birkedal 
Published: March 2022

Abstract
A nonlinear wear model for a cylinder rolling over a periodically varying surface is derived from the theory of half spaces. The model describes how some irregularities on the surface are amplified whereas others are levelled out as the number of cylinder passages increases. This is a pure nonlinear contact mechanical effect independent of the dynamic response of the cylinder and the support. The aim of the present work is to demonstrate, that these nonlinearities, which often are neglected in models for wheel/rail interaction, play an important role in the evolution of corrugation of rails.
A NUCARS Investigation of the Effect of Pedestal Liner Compliance on Rail Vehicle Hunting
Authors: Ahmadian Mehdi 
Published: March 2022

Abstract
The effect of pedestal liner compliance on rail vehicle hunting is investigated using a NUCARS simulation model of a heavy freight locomotive. The need for the pedestal liners, as well as some of the existing designs, is discussed. A new design for pedestal liners is recommended to improve the critical hunting speed of the railway vehicles. Different possible arrangements for the recommended design are also presented. Further, a NUCARS simulation model of a three-axle locomotive is used to show that the new design can significantly increase the critical hunting speed, without adversely affecting the curving performance of the vehicle.
On the Virtues of Steerable Locomotive Bogies
Authors: Ahmadian Mehdi 
Published: March 2022

Abstract
An overview of steerable bogies (or trucks) for railway vehicles is provided, along with their potential benefits to railroad operations. Some of the common designs for steerable bogies are reviewed. A NUCARS simulation model is used to compare a three-axle steerable and straight bogie in terms of their curving dynamics in 7.5- and 10-degree curves. The simulation results show that steerable bogies have a substantially lower axle angle of attack and wheel/rail lateral force. Further, the benefits of steerable bogies in terms of increased operational efficiency to the railroads are discussed.
Evaluation of Process Control During On-Line Consolidation of Thermoplastic Composites
Authors: Pistor Christoph M. , Yardımcı M. Atıf , Castro Raoul , Güçeri Selçuk I. 
Published: March 2022

Abstract
Laser assisted tape winding is a manufacturing technique to produce thermoplastic composite parts of high quality. It is an additive semi-freeform fabrication process that utilizes thermoplastic composite prepreg tape as the base material. The tape is fused by the heat delivered from a laser beam, while it is wound onto a cylindrical mandrel. To ensure proper consolidation to the substrate, a roller applies the necessary compaction pressure.
The fabrication of high quality rings with circular (Beyeler, 1988 and Irwin, 1994) and non-circular (Pistor et al. 1995) shape using quarter inch wide prepreg tape (PPS/Carbon, PEEK/Carbon) has been successfully demonstrated. The shape of the beam utilized in these investigations was determined by a series of lenses that formed the circular beam of the CO2 laser into a vertical narrow ellipse approximately 6.4 mm high and 2 mm wide (Pistor et al., 1995). The area illuminated by the infrared laser was therefore preset and not adjustable, limiting the set-up to the processing of quarter inch wide tape.
One of the advantages of using a laser beam for the consolidation of thermoplastic resins is the that extremely high heat trnsfer rates to the resin are possible. This can be exploited not only for laser power adjustments in response to variations in tape laying velocity (Pistor et al., 1995), but also for scanning of a circular beam spot over the desired consolidation area. For the described set-up, a vertical slit of adjustable height was realized by scanning the laser beam vertically with a frequency of 100–500 Hz. Scanning height and frequency as well as motion and laser power are computer controllable.
Characterizing the Microstructure of Fused Deposition Polymer Components
Authors: Rodríguez José F. , Thomas James P. , Renaud John E. 
Published: March 2022

Abstract
The speed and accuracy with which Fused Deposition (FD) ABS plastic components can be made gives this rapid-prototyping technology unique potential as a new method for manufacturing complex structural components. Quantitative relationships between the FD process variables and the resulting mechanical properties are needed for intelligent manufacture of polymer components with tailored strength properties. This work examined the influence of the process variables on the resulting microstructure (void and interface bond length densities) of two configurations with uniaxial fiber orientation. The results showed the void and interface densities to be strongly dependent on the fiber-to-fiber gap and extrusion flow rate settings; the influence of extrusion and envelope temperatures is much smaller. The skewed fiber configuration exhibited the lowest void density but also the lowest interface density values. However, the difference observed in the values for the interface density were not as big as for the case of the void density. An investigation of the influence of the process variables on the interface bond strengths and the tensile behavior of pre- and post-extruded fibers as a function of loading rate and test temperature is in progress.
Densification in Heterogeneous Powder Mixtures by Creep
Authors: Zavaliangos Antonios 
Published: March 2022

Abstract
Successful preparation of functionally gradient materials by powder metallurgy requires usually the application of external pressure. Therefore the densification of two component mixtures under pressure needs to be understood. In this paper we study the densification of a two phase powder mixture with the two constituents deforming by power law creep. A theoretical framework is presented and various aspects of the model are discussed.