bluuebunny/crossref_metadata_2025 huggingface dataset:
Impact Damage Resistance of Aluminum Alloy Foams
Authors: McRae Jametta , Kelkar Ajit , Grace Christopher , Craft William , Giamei Tony
Published: January 2022

While some polymers are engineered to improve strength and endurance under elevated temperatures, these same materials are costly both economically and environmentally with the latter of the two stimulating the interest for this study. Polymers, more specifically foam cells are generally flame retardant. When ignited, toxins such as fluorine, bromine and other metallic salts are given off in the air. This poses potential environmental hazards. However, metallic materials (Aluminum) with their high strength, stiffness and ductility are much more environmentally friendly. Even if alloyed with appropriate compounds, the resulting core material could be melted down, separated then cast into new stock. Moreover, the use of an alloyed material can generally enhance the strength and stiffness of sandwich composite structures so essential in aerospace applications.

United Technologies Research Center provided a plate of Aluminum alloy foam for impact testing by North Carolina A&T Researchers and graduate students. The material was provided by Austrian Metals Co. (AMAG) to UTRC under ONR Contract # N00014-95-C-0231, Thompson & Renauld (1997). All specimens were cut from one sample of nominal dimensions of 20 inches by 20 inches by 0.65 inches in thickness. The sample mass was 3142 grams and the apparent density was 0.737 g/cc. The chemical composition is close to that of 6061. The sheet sample was formed by AMAG and heat treated to T5 specifications consisting of 14 hours in a furnace at 160 °C.

Generally the bending stiffness and failure mechanisms were substantially different from those of polymeric foam sandwich cores made of Rohacell, a polymethacrylimide (PMI) foam in a prior study, Craft et al (1997). Rohacell is an easily machined, but a hygroscopic form with low shear strength and stiffness, but it and many other organic foams have a relatively uniform cellular construction in a wide variety of densities.
Fatigue-Life Prediction of SiC Particulate Reinforced Aluminum Alloy 6061 Matrix Composite Using a Weibull Distribution Model
Authors: Shan D. , Nayeb-Hashemi H.
Published: January 2022

This paper presents the feasibility of acoustic emission technique in predicting the residual fatigue life prediction of 6061-T6 aluminum matrix composite reinforced with 15 vol. % SiC particulates (SiCp). Fatigue damages corresponding to 40%, 60% and 80% of total fatigue life were stimulated at a cyclic stress amplitude. The specimens with and without fatigue damage were subjected to tensile tests. The acoustic emission activities were monitored during tensile tests. The number of the cumulative AE events increased exponentially with the increase of strain during tensile tests. This exponential increase occurred when the material was in the plastic regime and was attributed mainly to SiC particulate/matrix interface decohesion. The cumulative events during post fatigue tensile tests reduced with the decrease of the fatigue residual life. Based on the high cycle fatigue damage accumulation model, a Weibull probability distribution model is developed to explain the post fatigue AE activity of specimens during tensile test. Using the model, the residual fatigue life can be predicted by testing the specimen in tension and monitoring the AE events. In high cycle fatigue, it was observed that the residual tensile strengths of the material did not change significantly with prior cyclic loading damages since the high cycle fatigue life was dominated by the crack initiation phase.
A New Look at the Stochastic Linearization Technique for Hyperbolic Tangent Oscillator
Authors: Colajanni P. , Elishakoff I.
Published: January 2022

Stochastic linearization technique is reconsidered for oscillator with restoring force in form of hyperbolic tangent. We show that a subtle error was made in the previously known procedure for derivation of the linearized system parameters. Two new error-free procedures, namely, those based on minimization of mean square difference between (a) restoring force or (b) potential energy of the original non-linear system and their linear counterparts, are suggested. The results of numerical analysis are shown.
Monte Carlo Simulation of a Partially Submerged Compliant Structure
Authors: Adrezin Ronald S. , Benaroya Haym
Published: January 2022

The response of a single-tendon tension leg platform subjected to stochastic wave and current loading is presented with a planar motion assumption. The tension leg platform will oscillate about its vertical position due to ocean waves. Current will cause a tension leg platform to oscillate about an offset position rather than its vertical position. This offset in the surge direction has a corresponding set down, the lowering of the hull in the heave direction, which increases the buoyancy forces. This results in a higher tension in the tendons than if the tendon and hull were in a vertical position. In prior papers the equations of motion and forcing functions were fully developed. The tendon and hull are both assumed to be cylindrical and therefore Morison’s equation was applied. In this paper, a Monte Carlo simulation was performed on the drag and inertia coefficients in Morison’s equation. A uniform random distribution of coefficients was selected from 0.6 to 2.0 for each coefficient. Twenty computer simulations were implemented for each coefficient. The response showed that the offset position and the amplitude are both dependent on the drag coefficient. The surge of the hull shows a maximum offset approximately three times greater for the coefficient that resulted in the maximum displacement than the minimum. The response did not show a significant dependence on the inertia co-efficient, however, this is not necessarily true for unsteady current, large hull and tendon diameters, ocean wave frequencies greater than 1 radian/second, and low current velocity.
A Solid-Fluid Coupling Computing Method for Design High Speed Spindle Cooling System
Authors: Liu D. S. , Lee T. C.
Published: January 2022

High speed spindle is the key component for high precision machine center. The optimum design of spindle cooling system have to achieve to avoid the high heat produce by the build-in motor that can make great damage to the spindle bearing systems. This paper presents a new solid-fluid coupling computing method for design high speed spindle cooling system. Energy equation has been formed for a control volume within the cooling channel to described the heat absorbing by the coolant moving in a constant speed. Finite different method is applied to solve temperature rising in the coolant and coupled with a 3-D finite element structure heat transfer program which can solve temperature distribution due to heat produce from build-in motor. An experimental testing setup is using to verify this solid-fluid coupled program. The numerical results agree well with experimental data. The effectiveness of straight heat-pipe-type cooling system and helical heat-pipe-type cooling system are compared by applied this methodology. The numerical methods developed in this research can offer the spindle designer a new tool to improve spindle cooling system design.
Designing Machine Tools to Minimize Life Cycle Cost
Authors: Carter Michael F.
Published: January 2022

This paper describes a methodology used in the design of manufacturing machines to minimize life cycle cost. Life cycle costs include design, construction, installation, planned maintenance, repair, disposal and lost production caused by breakdowns. Studies have suggested that maintenance accounts for half of life cycle cost, and the primary focus of this methodology is to reduce repair and maintenance costs. This methodology has on average resulted in a 10 percent savings in capital investment, a 50 percent reduction in lifetime maintenance costs and a significant improvement in up-time.
Design for Quality Approach to Improve Surface Roughness in Milling Operations
Authors: Abdou G. , Basaly N. A.
Published: January 2022

Tooling related malfunction is of particular concern, since tooling condition can cause loss of dimensional part accuracy and loss of the required surface finish. Out of specifications surface parameters will often be confined to less than quality making features and hence affect manufacturability. There is an eminent need for a methodology that enables process designers to evaluate and improve the quality manufacturability of the milling process before machining. This paper describes a methodology of design for quality manufacturability that enables product designers to evaluate, quantify and improve surface roughness in the design stage for milling operations. Different experiments have been conducted to measure cutting forces and surface roughness parameters under dry cutting conditions. The relationships between different operating parameters to the cutting force and surface roughness parameters were examined through extensive experimental work. Different relationships have been developed between five surface roughness parameters and three operating parameters. Further analysis has been conducted on the cutting force pattern: seasonal pattern, nonlinear trend and peak. The results generated from the study are very important for the parameters’ design of manufacturability for the milling operation. The basis for the design for quality is a set of common classes of quality defects (errors), and a set of factors that influence the occurrence of the less quality. The concept of quality errors and the derivation of the index matrix are presented.
A Stress and Relative Density Dependent Dynamic Compliance Spectra Model of the Creep Response of Microcellular Polycarbonate
Authors: Armstrong William D. , Kumar Vipin
Published: January 2022

The present paper reports a new stress and relative density dependent discrete dynamic compliance spectra method which may be used to model the creep behavior of nonlinear viscoelastic microcellular materials. Comparisons between model calculations and experimental measurements show that the model exhibits excellent quantitative agreement at all experimental stress-relative density states. A designer may use the present method to predict the creep strain resulting from a broad range of specific stress-relative density combinations, or to identify relative density ranges over which the material provides relatively stable creep properties.
Bubble Growth in Thermoplastic Foam Extrusion
Authors: Ramesh N. S.
Published: January 2022

A condensed review will be presented regarding the bubble growth study. A modified model fitting to foam extrusion system will be discussed. The improved model focuses on the influence of blowing agent on bubble growth during thermoplastic foam extrusion. Extrusion has been conventionally used for producing low-density foam sheet and rods with physical blowing agents in the last decades. Foam nucleation, bubble growth, and cell coalescence are the three major events in the foaming process. Only the bubble growth study is addressed here. The bubble growth is influenced by the concentration-dependent blowing agent diffusion coefficient, transient cooling of the expanding foam, influence of blowing agent on polymer viscosity, and the escape of blowing agent from the surface of the foam. The blowing efficiency is affected by the escape of gas from the cells closer to the surface of the foam. Previous models in the literature do not consider these significant influences. A modified model will be presented accounting for those more subtle effects. In addition, a new experimental technique will be described to collect experimental bubble growth data. Predictions of the new model reasonably agree with the experimental data.
Foaming of Poly(Ethylene Terephthalate) Modified With Tetrafunctional Epoxy
Authors: Japon Sonia , Boogh Louis , Leterrier Yves , Månson Jan-Anders E.
Published: January 2022

A reactive process is developed to extend the recycling of poly(ethylene terephthalate) (PET) into high-value applications, in particular into foam core sandwich structures. To achieve a cellular structure, a high extensional viscosity is required to prevent foam collapse during the final stabilisation phase of the extrusion process. This is obtained by reacting PET with tetrafunctional epoxy-based modifiers, which induce branching and a certain amount of crosslinking. The modification of the chemical architecture leads to a 50-fold increase in the apparent extensional viscosity. With these modified materials closed-cell foams are obtained using carbon dioxide as a foaming agent.
Some Research Activities and Opportunities in Smart Materials and Structures
Authors: Chong Ken P. , Larsen-Basse Jorn
Published: January 2022

Adaptive, or “smart” materials, materials systems, and structures have been the focus of considerable research during the past twenty years or so, and have increasing promise for many different applications. We are here presenting a small sampling of some of the engineering-related research in this area that NSF has supported in the recent past or is currently supporting. We specifically focus on two diverse general topic areas with which we have been associated: civil infrastructure systems structures and engineered surfaces of materials. We make some personal observations on what we think are some of the emerging research opportunities and needs. A major driver for research in this area will probably be the search for various engineering “fixes” for environmental problems that our technology has created and the need for closer control with processes of all sorts. Development will be supported by advances in distributed intelligence, MEMS, nano-technology, digital simulation, modeling, materials science, etc.
Experimental Results for Magnetostrictive Composites
Authors: Duenas Terrisa A. , Carman Gregory P.
Published: January 2022

This paper contains experimental results for magnetostrictive composites containing Terfenol-D (Tb0.3Dy0.7Fe2) particulate embedded into an epoxy binder. Composites of 10% to 40% volume fraction were manufactured to produce pseudo 1-3 magnetostrictive composites. In an absence of a mechanical preload, the 20% sample produced strains exceeding 1000 microstrains; the larger volume fraction samples — i.e., 30 and 40% achieved only half of this value. Under an applied preload both the 30% and 40% samples produced strain output exceeding 1000 microstrains. Analytical results are presented to explain this experimental data.
A Large Stroke, Nanometer Precision X-Y Stage for Lithography
Authors: Jones Lowell D. , Paine Jeffrey S. N.
Published: January 2022

The state-of-the-art in the microelectronics industry is being pushed primarily by two motivations: the demand for more circuitry etched per unit area and the demand for higher throughput. Both of these needs can be met by an increase in the speed and/or the resolution of lithography positioning equipment. Presented herein is an attempt to develop an innovative X-Y stage design through which control of positions on the order of nanometers will be possible while simultaneously increasing stroke length to 300 mm per axis, the maximum speed to 1 m/s, and the turnaround time to under 100 ms. The proposed design will approach this problem by incorporating a macro-micro positioner analogous to an audio “woofer-tweeter” arrangement for each axis of the stage. This approach will allow for a decoupling of the positioners coarse and fine motion properties simplifying components and design of the entire system. While this approach is not unique to lithographic stages it does offer the innovation of using a piezoelectrically actuated flexure mechanism for the tweeter as opposed to the typically employed magnetic levitation based tweeter. Piezoelectric actuation is superior to voice coil actuation in this application due to its simplicity, lower mass, and most importantly, its low heat generation. Two additional features are also incorporated in the design for the minimization and localization of heat generation. The first feature is configuring the stage in a mechanically parallel fashion in order to minimize parasitic inertia and locate the woofer’s actuators at ground. The second feature is the selection of rotary motors to drive the linear woofer stage through cable transmissions.
Control of Random Vibrations of Composite Plates With Piezoelectric Actuators
Authors: Lee Yiu-Yin , Mei Chuh , Huang Jen-Kuang
Published: January 2022

A study of the use of H∞ control design to suppress the vibrations of composites plates embedded with piezoelectric actuators under random loading is presented. The finite element method is employed to obtain the dynamic equations of a plate vibration of fully coupled structural and electrical nodal degrees of freedom (DOF). The modal reduction method is adopted to reduce the finite element equations into a set of modal equations with fewer DOF. The modal equations are then employed for controller design and simulation. Results of the modal convergence study of the closed loop systems show that the truncated modes, which are neglected in the control design, deteriorate the controller performance and affect the optimal location and size of the actuator. The vibrations of plates subjected under off-resonant narrow-band excitations cannot be suppressed effectively. The controller shaped with an extra weight function for mitigating measurement noise effect gives better vibration reduction performance.
Comparative Assessment of Optimal Control Methods With Integrated Performance Constraints
Authors: Smith Malcolm J. , Koko T. S. , Orisamolu I. R.
Published: January 2022

The relative performance of optimal vibration control methods is investigated within the context of integrated finite element modeling of piezothermoelastic structures. An IMSC and a LQR optimal control method are modified to include explicit performance constraints related to the transient settling time and steady-state gain of the modal response. When this approach is applied to the IMSC method, the result is a pole placement technique. But when it is applied to the LQR method operating in a modal subspace, the result is a method incorporating both optimal and pole placement features. The two methods are compared by means of a transient response analysis of an aluminum strip with piezoceramic sensing and actuating patches. For identical performance constraints and using identical modal subspaces, it is found that maximum actuator voltages and their distribution vary according to the control design method and the number of modes under control. In particular, it was found that the maximum actuator voltages are less for LQR than for IMSC. This is attributed to difficulty in controlling the second bending and first torsional modes of the strip independently. It is also found that for a given number of controlled modes, the maximum actuator voltage varies in a manner approximately inversely proportional to the settling time.
Evaluation of Fiber Optic Sensors for Measuring Strain in Aircraft Applications
Authors: Tarter Jim , Sirkis Jim , Boyer Tom
Published: January 2022

This paper describes the application of in-line fiber etalon (ILFE) fiber optic sensors to the measurement of strains generated in an aircraft system. Single channel phase tracker and active homodyne demodulation schemes were tested simultaneously, but with different ILFE sensors. Cantilever beam and full scale strain measurements compared well with resistance strain gage measurements. This program gave insight to further applications of advanced optical fiber sensors to the harsh environments typical of in-service aircraft systems.
Crash Energy Management of Aluminum Components
Authors: Weinhold Volker , Baccouche Mohamed Ridha , Hasan Abid
Published: January 2022

Automobile manufacturers increasingly desire to produce vehicles that are not only fuel efficient and environmentally friendly, but also, light weight and structurally safe. Vehicle weight plays an important role in fuel consumption and is relatively effected by the size of structural components and powertrain.

The quest to reduce vehicle weight without jeopardizing structure’s crash energy management has lead to investigating materials other than steel, i.e., aluminum, composite, magnesium etc. In this regard, aluminum is the most popular material that is prominent due to its tangible material properties. Aluminum space frame and extruded aluminum components are widely used in the automotive industry, especially in low volume and niche vehicle programs, and in programs where significant weight reduction has to be achieved.

The structural components of aluminum space frame can be designed to achieve high energy absorption under various crash conditions (i.e. full front and offset crash against rigid and deformable barriers). Techniques are available to downgage or reinforce components where needed, so that excellent crash performance (axial collapse as well as local bending) can be achieved within weight targets. This enables for a flexible adjustment of various vehicle architecture parameters (i.e., front rails height, vehicle length and width) which, again, is ideal for low volume approaches.
Generic Tube Crush Program: Crush Tests of Structural Reaction Injection Molded Tubes
Authors: Johnson Nancy L. , Houston Dan Q. , Watling Patrick J. , Lalik Larry
Published: January 2022

This paper documents the structural reaction injection molding (SRIM) portion of a generic crush study of glass fiber reinforced composite tubes conducted by the Energy Management Working Group of the Automotive Composites Consortium (ACC). Static and dynamic crush tests were performed to evaluate the crush performance of square, circular, and rectangular shaped cross-section tubes. Manufacturing of the tubes for this study required feasible processes for production such as resin transfer molding (RTM) and SRIM, in conjunction with rapid preforming and foam core fabrication. Square (55 × 55 mm), circular (63.5 mm diameter), and rectangular (38.1 mm × 71.1 mm) crush tubes had a nominal wall thickness of either 2.54 or 5.08 mm and a length of 230 mm. Dow Spectrim MM364 resin was used for all the tubes in this portion of the study. Seven different fiber architectures were considered ranging from random chopped mat (RCM) to a tri-axial braid. The principal fiber was E-glass with a limited number of tubes being constructed with S-2 glass. A plug-type initiator was used in combination with a 45° bevel on the outside edge of the lead end of the crush tube to ensure progressive crush. Crush tests were performed at −40°C, room temperature, and 82°C. The tubes tested at high temperature were immersed in distilled water for 24 hours prior to heating. Various fiber architectures, wall thicknesses, and temperatures were evaluated for their effect on energy absorption characteristics during axial crush using plug-type initiators. Principle findings were that different fiber architectures can produce significant differences in tube specific energy absorption (SEA), that SEA increases dramatically with increasing tube wall thickness, and that post-curing can increase the SEA of the tubes. Static tests produced higher values of SEA than those measured in dynamic tests for most fiber architectures at cold and room temperatures, while at elevated temperature / humidity, the opposite effect is seen in that static values were lower than dynamic values of SEA.
An Analytical Study of System Variables for Meeting FMVSS 201 Head Impact Requirements
Authors: Zhou Qing , Thomas Mohan P. , Stibich Anne M.
Published: January 2022

A hypothetical acceleration pulse, asymmetric haversine wave, is used to analytically model acceleration pulses of FMVSS 201 head impact tests. This model leads to general relations among a few key variables in head impact tests including Head Injury Criterion (HIC), initial impact velocity, and stopping distance. As a result of this analysis, a preferred design range of stopping distance is identified and HIC sensitivity to impact velocity is revealed. Parameters that can assess energy absorbing efficiency of a head impact countermeasure are defined and discussed. The model may be used to guide the design of vehicle interior trim for meeting FMVSS 201 head impact requirements and has been validated using test and finite element results.
Nonlinear Lumped-Parameter Model of Unconstrained Standing Postured Personnel Subjected to Vertical Upward Shock
Authors: Liu Xinxiang
Published: January 2022

The Standing and seating postures are two kinds of most common working postures in the warship. Therefore we need take these two postures into consideration when we study the biodynamic response and injury prediction of ship personnel subjected to vertical shock motion induced by underwater explosion. This paper will describe a biodynamic model of unconstrained standing postured personnel.
Effect of Distance Between Fins on the Hydrodynamics in a Fin-Tube Heat Exchanger
Authors: Romero-Méndez Ricardo , Sen Mihir , Yang K. T. , McClain Rodney L.
Published: January 2022

In this work we study the hydrodynamics of flow around the tubes of a single-row fin-tube heat exchanger. The study includes numerical analysis using finite elements and flow visualization experiments in a water tunnel. It is found that the nature of the flow is greatly affected by the distance between fins. For small distances, the flow is of the Hele-Shaw type without separation. As the distance between fins is increased, a separated region is formed behind the tube which may become unsteady and lead to vortex shedding. Also affected in a similar fashion by the distance between fins is the horseshoe vortex that exists just upstream of the cylinder.
Reconstruction of Steady Flow Field by Electromagnetic Tomography
Authors: Honda S. , Trächtler A.
Published: January 2022

Magnetic flowmeters, which have been one of the standard instrument to measure flowrate of the liquid with electrical conductivity in industry, were applied to tomographic imaging of flow velocity field, based on the fact that there are no exciting magnetic fields that induce the flow signal proportional to volumetric flowrate free from the flow profile. Previous 2-D reconstruction method is examined through 3-D analysis, and feasibility conditions are clarified.
Geostatistical Analysis of TPH Degradation in Field Soils
Authors: Govindaraju R. S. , Nedunuri K. V.
Published: January 2022

Evaluation of remediation strategies in the field is difficult because of the inherent spatial heterogeneity in the hydraulic and chemical properties of the soil. In this study, total petroleum hydrocarbon (TPH) degradation was monitored over a field site with three vegetative treatment plots, and one control plot undergoing natural attenuation. First-order kinetics were assumed applicable at the local scale. The degradation rates and the initial contaminant concentrations were treated as spatially correlated random fields. Our results indicate the importance of spatial variability for an accurate assessment of phytoremediation in the field.
Comparison of First-Order Turbulent Models’ Predictions of Flow About Steps/Buildings
Authors: Brzoska Michael A. , Stock David E. , Lamb Brian K.
Published: January 2022

Flow over back-facing and front-facing steps and three-dimensional buildings were modeled with the standard k-ε, strain/vorticity modified k-ε, k-ω, and modified k-ω models. Comparisons were made between models and to experimental work (Moss and Baker. 1980). Discussion of reasons for variations in models and deviations from experiments are given.
Application Techniques for a Gamma IIPlus Parallel Computer
Authors: Flanders Peter , Kennedy John , Hunt David , Yadegar Joseph
Published: January 2022

Exploiting high degrees of parallelism available in certain computer architectures offers the promise of ever-increasing power for the needs of scientific and engineering users; for example, in the fields of image and signal processing [11, 12], computational fluid dynamics [1, 13], finite element methods [8], optimization [7, 15] and neural networks [14, 16]. It also introduces the challenge of how to make the best of the available power. High level languages, for those parallel machines provide a good interface between a problem and the processor, thus aiding straightforward use of the parallelism. However, to get the very best performance, something more than minimal alteration to existing algorithms is needed. Since operations will normally be specified on sets of data items rather than on scalars, the recommended approach may be summarized as “think parallel”.
Statistical Analysis of Experimental Results in Amplitude and Frequency Domains for Two-Phase Flow
Authors: Keska Jerry K. , Smith Michael D.
Published: January 2022

This paper presents the results and analysis of in-situ air and water velocities, concentration and their impact on other parameters of multi-phase flow such as flow patterns. Experimental data of in-situ physical parameters such as spatial concentration, mixture velocities, and pressures are presented in time, amplitude and frequency domains. These experiments were conducted in a developed system, which includes a vertical square shaped channel with computer aided measurement systems, interfaced with a CADAS (Computer Aided Data Acquisition System).
Concurrent Product Design and Manufacture: A Case Study on Infopad, a Wireless Network Computer
Authors: Wang Fu-Chung , Wright Paul K.
Published: January 2022

In this paper, a case study on the mechanical design and fabrication of Infopad, a multi-media, portable wireless computer is presented. A collaborative design environment that supports the design activities is also briefly described. A particular focus is on the systematic design process and resolving coupling design constraints between mechanical and electrical domains. Some of the design techniques used during the development process are applicable to the collaborative product development for more modular, reconfigurable electromechanical products.
Part and Workpiece Reconfigurability for Reconfigurable Machining Systems
Authors: Raghunandan Shyam , Yip-Hoi Derek , Dutta Debasish
Published: January 2022

A Reconfigurable Machining System (RMS) is a new paradigm for production systems that addresses the need for introducing greater flexibility into high production machining environments where changes in production requirements (product volumes and mixes) occur regularly. Unlike Flexible Manufacturing Systems (FMS), an RMS applies flexibility only when, where and to the extent that is needed in a machining system. Characteristics such as modularity, scalability and reusability of machining and material handling elements are needed if an RMS is to achieve this objective. The concept of part and workpiece re-configurability complement that of RMS reconfigurability. This paper presents the concept of a reconfigurable workpiece and investigates a methodology for its generation when a combination of turning and milling operations are required.
Dynamic Modeling of Linear Piezomotor
Authors: Zhang Bi , Zheng Xiaolin
Published: January 2022

A two degree-of-freedom dynamic model is presented to simulate the motion characteristics of an inchvvorm type linear piezomotor. With the consideration of the sequential motions of the piezoelectric actuators in the piezomotor, the model handles the piezomotor as a two degree-of-freedom dynamic system with varying interface stiffness and damping coefficient. It incorporates the electromechanical coupling effect into its governing equations. The model is demonstrated using co-quad plots, root locus method as well as frequency and step response techniques, and verified by an experimental study. It turns out that the model can precisely predict the motion behavior of the linear piezomotor. The model can be used to improve the performance of the existing linear piezomotors and to help design new linear piezomotors.
A Hybrid Model for Piezo Actuators
Authors: Song Dongwoo , Li C. James
Published: January 2022

To facilitate on-line identification and implementation of a piezoelectric model for precision machining, this paper describes a hybrid hysteresis model integrating the Preisach model and a neural network. The incorporation of a neural network enables 1) on-line model identification from operating data of a piezo (a great contrast to the tedious calibration process required by the Preisach model.), 2) no explicit implementation of interpolation and extrapolation in the model, and 3) real-time implementation due to the parallel architecture. Experimental results confirmed the accuracy of the model and its ability to generalize.
Virtual Fabrication of an 0.25 um Integrated Circuit Device Using TCAD
Authors: Chin Chi-Te , Fordemwalt James N. , Mou Jong-I
Published: January 2022

A complimentary metal-oxide-semiconductor (CMOS) device has been designed and virtually fabricated utilizing a minimum complexity salicide gate process, with the drawn transistor channel length of 0.25 um and effective transistor channel length of 0.22 um. Thin TiSi2 is utilized for poly and diffusion sheet resistance reduction while maintaining excellent junction characteristics. A functional 0.25 um CMOS ring oscillator circuit then was successfully simulated by linking four separate technology computer aided design (TCAD) tools. This high performance 0.25 um CMOS ring oscillator with a reduced operating voltage of 2.0 V is presented. Stage delay as low as 1ns (Vdd = 2V) for an unloaded inverter ring oscillator was obtained. The reduced operating voltage and the use of lightly doped drain (LDD) source/drain junctions achieve high performance with sufficient hot carrier immunity.
Femtosecond Lasers for Advanced Machining of Ceramics and Composites
Authors: Malshe A. P. , Railkar T. A. , Ozkan A. M. , Molian P. A. , Brown W. D.
Published: January 2022

In the past few years, novel femtosecond (fs) laser-induced material processing has been the area of tremendous interest [1–10]. The purpose of this paper is to review the state-of-the-art in femtosecond laser machining of ceramics and inorganic composite materials. Femtosecond lasers are attractive tools for micromachining because of the fact that the processing time scale is of the order of a few tens or hundreds of femtoseconds, which is far shorter than the time scale over which atomic vibrations occur. Thus, the heat affected zone (HAZ) is minimal while dealing with fs-laser processing, which results in clean and controlled material processing. On the contrary, conventional nanosecond lasers are fast approaching their intrinsic limitations for micromachining application because of the HAZ they create upon interacting with materials.
Impact of Die Manufacturing Errors on the Drawbead Restraining Force
Authors: Seshadri Narasimhan , Wu Xin , Hu S. Jack
Published: January 2022

In this paper, the impact of die manufacturing errors on the drawbead restraining force is studied for straight and curved drawbead systems. The effect of manufacturing errors, including machining and assembly errors, is studied through a finite element analysis (FEA) model. The modeling procedure is validated for a single case by experiments, and compared to the existing drawbead data in the literature. The results indicate that for the curved drawbead system, the restraining force increases with curvature. The restraining force of the curved system is close to the sum of the contributions from an identical straight drawbead system and the metal flow-in deformation of the curved flange. Also, the sensitivity of the restraining force for the curved drawbeads to the machining errors, is similar to that of the straight drawbeads.
Effects of Edge Preparation and Cutting Speed on Surface Integrity of Die Materials in Hard Machining
Authors: Kishawy Hossam A. , Elbestawi Mohamed A.
Published: January 2022

In this paper, the effects of edge preparation and cutting speed on surface integrity during machining of D2 tool steel (62 Rc) are examined. Tool wear, and surface finish are also measured and investigated. The x-ray diffraction technique is employed to measure the residual stresses distribution beneath the machined surface. The machined surface and subsurface are examined using optical and scanning electron microscopy. The thermally induced white layer is also investigated under different culling conditions. The results obtained show that the residual stresses induced are dependent on the combined effects of cutting conditions and the tool wear. Different types of surface and subsurface damage are also observed.
Diagnosability and Measurement Configurations for Automotive Body Assembly
Authors: Long Yufeng , Hu S. Jack
Published: January 2022

An automotive body assembly system usually consists of processes and machines in a multi-leveled hierarchy. As a result, dimensional variation in the final product is accumulated as the product moves along the assembly system. To identify variation problems in such a complex system, proper design and placement of measurement systems is essential. In this paper, analytical models are proposed to aid the design of measurement configurations. First, the concept of assembly fault diagnosability for automotive body assemblies is introduced so that which stations or subassemblies in the multi-leveled assembly system need to be measured can be identified. Second, quantitative indices are proposed to evaluate measurement configurations so that effective fault diagnosis can be achieved optimally. Finally, a simple 1-D sheet metal assembly and an automobile door assembly are given as examples to demonstrate the effectiveness of the proposed methodologies.
Characterization of Cutting Fluid System Dynamics
Authors: Filipovic Aleksandar J. , Gowaikar Hrishikesh , Olson Walter W. , Pandit Sudhakar M. , Sutherland John W.
Published: January 2022

Cutting fluids can not be disposed of into municipal sewage treatment systems. Therefore, used cutting fluids require significant treatment before they may be disposed of safely. The cost of disposing the cutting fluids is a significant part of the entire manufacturing costs. One way of reducing both environmental impact and the disposal cost of a cutting fluid is to extend its life cycle. For this purpose, it is necessary to investigate the degradation dynamics of the cutting fluid system. In this project a cutting fluid system degradation dynamics was modeled.

Autoregressive, moving average, (ARMA) models characterize system dynamics by statistically analyzing historical data. ARMA models were used here to formalize and characterize the dynamics of cutting fluid systems. Modeled data included daily system measurements and the any changes made to the system through additives. Daily monitoring comprised of measuring the following cutting fluid characteristics: pH, oil concentration, dust, rust. Depending on the evaluation of these characteristics, additives (caustic, oil concentrate, biocides) were used to improve the system parameters. This data was maintained by the system contractor and was used in the ARMA analysis.

The objective of the analysis was to optimize the system so that cutting system degradation was minimized. System control functions were developed to determine the timing and amount of additives needed to extend fluid life. Transfer functions that relate the dynamics of the system to the applied controls including oil concentration behavior to added oil, and pH change to the addition of caustic were developed. The mathematical models were verified by using forecasting system responses and comparing the model predictions with the actual data. Some key properties of a cutting fluid system dynamics are identified and explained.
3-D FEM of Residual Stresses in CVD Diamond-Coated Carbide Cutting Inserts for Process Optimization
Authors: Taher Mahmoud A. , Schmidt William F. , Malshe Ajay P.
Published: January 2022

The high thermal strains that generate during chemical vapor deposition (CVD) of diamond coatings on carbide inserts result in high compressive thermal residual stresses in the diamond near the coating interface. These stresses are believed to increase the strain energy at the interface leading to coating failure. To help predict CVD diamond adhesion characteristics to carbide inserts, quantifying such residual stresses becomes important. A three dimensional finite element model was constructed for a commercial cemented carbide tool insert coated with a 20μm film of CVD diamond and the interfacial thermal residual stresses at the rake and flank regions computed. A 2-D axi-symmetric contact model was constructed to evaluate the effectiveness of mircohardness indentation as an appropriate adhesion test for CVD diamond coatings. Superposition of the residual stresses and the stresses generated by indentation just before cohesive brittle failure of the coating revealed that the combined shear and peel stresses were lower than those originally present due to residual stresses alone indicating that the indentation method may not be a useful technique for determining adhesion.
Identification of Multiple Feature Representations by Volume Decomposition for 2.5D Components
Authors: Sundararajan V. , Wright Paul K.
Published: January 2022

Decomposition of CAD models into features that can be directly manufactured and easily translated from one representation to another has been recognized as a necessity for robust automated process planning systems. The algorithms presented here yield multiple representations of features that can be used to generate optimal plans and that are easily manufacturable by milling processes. Features are recognized from the faces of a prismatic stock by first identifying missing regions on the external faces of the stock and then recursively descending into the part. Each missing region corresponds to a feature. As the projection of the feature is swept into the part, changes in the cross-section are identified. These denote the beginning of new features which become children of the original feature. This process yields a set of six trees, each of which resembles a depth-first search tree and is a partial ordering of features within a setup. Multiple representations are investigated for those features that are accessible from more than one direction. Corresponding features in the different trees are linked by arcs, thus yielding a feature graph. The feature graph can then be used to generate optimal features for machining depending on design or manufacturing requirements such as fixtures, tolerances, corner radii and tool accessibility.
Geometry for Precision Manufacturing on an Open Architecture Machine Tool (MOSAIC-PC)
Authors: Hillaire Robert G. , Marchetti Louis A. , Wright Paul K.
Published: January 2022

Modern machine tools cannot presently machine all the desired geometries modeled by designers. These geometries include free-formed surfaces represented by Bezier, Tensor Product, NURBS, and the like. When these free-formed surfaces are executed on the production floor, they are approximated with straight lines, circles, and in some advanced manufacturing facilities, cubic B-Splines.

The work described in this paper provides a machine path interpolator that can traverse complicated free-formed paths represented by NURBS. This NURBS interpolator is implemented on a three axis milling machine with an industrial quality Open Architecture Controller. The system is called MOSAIC-PC (Machine-tool Open System Advanced Intelligent Controller: PC platform).
Improving Multi-Axis Contouring Accuracy Using Neural Networks
Authors: Aziz Sarmad , Spence Allan D.
Published: January 2022

The contouring accuracy of a multi-axis machine is affected by the presence of geometric errors, caused by structural imperfections of the machine links and guideways. In recent years, homogeneous transformation matrices and rigid body kinematics have been successfully utilized to model the effects of these errors and to predict the actual tool position in the machine workspace. However, for contouring applications the command coordinates provided to the motion controller must be corrected to attain the desired actual coordinates. This task requires solving the inverse kinematics of the machine error model. In this paper, a direct method for solving the inverse kinematics of a Coordinate Measuring Machine (CMM) is proposed using Radial Basis Functions (RBF) neural networks. By training the neural network to learn the inverse kinematics of the machine error model, the position error vector at any point with in the workspace can be predicted. A novel training strategy is implemented where the spatial deformation of the machine workspace is captured using Self-Organizing Feature Maps (SOFM) and incorporated into the design and training of the RBF network, thereby enhancing its accuracy.
Hexapod Machine Tool Error Analysis With Inclusion of System Dynamics
Authors: Wiens Gloria J. , Walker Craig W.
Published: January 2022

Parallel robotic manipulators have been in use in industry for many years. For machine tool applications the overall tool tip error in position and orientation is of most concern. In this paper, the effect of various sources of error on overall positioning error from both a kinematics and a dynamics point of view is investigated. A comprehensive model for the Ingersoll Octahedral Hexapod milling machine is developed. A full dynamics simulation with feedback control is developed to implement emulation algorithms for error sources (e.g., joint stiffness, thermal expansion, joint location, and load). The error analysis methodology presented in this paper provides insight into how error sources play a role in platform positioning errors when the system dynamics are considered.
Design, Calculation and Control of Machine Tools Based on Parallel Kinematics
Authors: Weck Manfred , Dammer Michael
Published: January 2022

By the application of high speed cutting (HSC) technologies a reduction of the production times becomes possible. Unlike the conventional cutting process the high speed cutting makes high demands on the material of the cutting tools as well as on the machine tool itself (Schulz 1989, Weck and Schumacher 1997). To realise high speed cutting the development of new machine tool components and concepts is necessary. On this background new developments of the kinematic structure of the machine tools, e.g. the Hexapod, will be done. After a short introduction in machine tools based on parallel kinematics we will present methods and tools for the development of new kinematic concepts.
A System for First Order Reliability Estimation of Solder Joints in Area Array Packages
Authors: Deshpande Anand M. , Subbarayan Ganesh , Rose Dan
Published: January 2022

In this paper, a methodology, and a program based on the methodology are presented using which the reliability of solder joints for various values of design/process parameters can be estimated in seconds on a personal computer. The proposed methodology accurately captures the behavior of a solder joint in an artificial neural network (ANN) model trained to relate design as well as analysis parameters to fatigue life. The proposed methodology is novel since such simultaneous analysis and design (SAND) procedures do not appear to have been employed until now for reliability estimation of solder joints. The use of Moiré interferometry as an experimental technique to estimate the analysis-related inputs to the neural network model is also presented in the paper.
Monitoring End-Mill Wear and Predicting Tool Failure Using Accelerometers
Authors: Roth John T. , Pandit Sudhakar M.
Published: January 2022

Autoregressive models are fit to end-milling acceleration data and the Data Dependent Systems methodology is utilized to isolate the modal energies of the first and second multiples of the tooth pass frequency. The modal energies are shown to be closely linked to the wear curve and a detection scheme is developed that is capable of tracking the end-mill’s wear and providing an early warning of impending failure. Six life tests are conducted under varying conditions to demonstrate the capabilities of the detection scheme: standard cutting conditions, extreme cutting conditions, premature catastrophic failure and accelerometer placement. In all six cases, the detection scheme was able to provide a warning of impending failure several centimeters before the failure occurred.