bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ballistic Impact Response of Foam-Filled Sandwich Composites
Authors: Vaidya Uday K. , Mathew Biju , Ulven Chad A. , Sinn Brent , Velazquez Marian 
Published: November 2021

Abstract
Sandwich composites find increasing use as flexural load bearing lightweight sub-elements rail / ground transportation and marine bodies. In recent year, alternatives to traditional foam and honeycomb cores are being sought. One such development includes filling the cells of the honeycomb core with foam. The increased surface area allows stress forces to dissipate over a larger area than that offered by the honeycomb alone. This allows for use of lowering the cost of the honeycomb cells, and thereby making the design extremely cost-effective. In the present research, phenolic impregnated honeycomb / corrugated cells with polyurethane foam filling has been considered. The intermediate and high velocity impact response of these types of sandwich constructions has been studied. The applications for such cores would be in rail and ground transportation, where impacts in the form of flying debris are common.
Modeling of Joints and Effect on Crash Simulation
Authors: Tyan Tau , Guimberteau Thierry , Faruque Omar 
Published: November 2021

Abstract
This paper reports the findings of a study that was conducted to evaluate the effect of joints and their proper modeling technique in the crash analysis. Joints such as universal joints, lower control arm connections, etc. are generally not characterized in details in the current CAE models used for crash simulation. In the past, assumption was that crash is a short duration event and therefore accurate modeling of the joint kinematics is relatively less important for crash simulation. However, review of many recent crash tests have shown that some of the critical joints in the vehicle may undergo severe joint motion during crash affecting the crash modes and the responses in a significant way. Especially, in some offset crash tests, tire was found to rotate inward and caused significant toe-board intrusion. Improper modeling of the mechanical joints sometimes can lead to inaccurate prediction and jeopardize the design verification process.
To study the effect of joints on crash responses, detailed models for the major joint types in the vehicle were developed. Four types of joints — spherical, revolute, cylindrical and universal joints, have been identified and investigated since they are used extensively in the design of vehicle’s chassis. In particular, attention was focused on accurately simulating the kinematics of the joints under various loading and impact conditions. Component modeling of the four joints was investigated first to ensure the proper motion of the different joints individually. A number of analyses were conducted with the models for different impact conditions. The joint models, thus verified, were incorporated into sub-system models to verify the responses of multiple components and joints. Finally full vehicle simulations, with and without these joints, were performed and compared with physical test to prove out the joint modeling methodologies. Both car and truck chassis were included in the full system study to examine the robustness of the models. The results showed that the inclusion of the joints in the CAE models can affect the simulated responses significantly.
Teaching MEMS to Mechanical Engineering Students: A Paradigm Shift From Macro to Micro World
Authors: Kao Imin 
Published: November 2021

Abstract
This paper presents pedagogical issues and experience in teaching the introduction to MEMS (Micro Electro-Mechanical System) course to a group of engineering students, primarily Mechanical Engineering students. The paper draws upon the author’s experience in teaching the MEMS course. Since MEMS is highly inter-disciplinary, the presentation of various relevant topics in MEMS, which may or may not be familiar to a mechanical engineering student, is of critical importance. These topics vary from physics, electrochemistry, materials, and electronic engineering, to various areas in mechanical engineering. An integrated approach for the presentation of subjects, especially in design and fabrication, was found to be very helpful. Moreover, the paradigm shift from the macro world, that most students are familiar and comfortable with, to the micro world is significant and needs to be emphasized. The author found the concept of scaling law, when shifting to the micro world, to be essential in the presentation of MEMS to engineering students in order for them to comprehend the size factor in MEMS. In addition, understanding and appreciation of the strengths and limitations of MEMS are also critical in learning MEMS. Finally, a good textbook will facilitate the learning process of such vast subject. A bibliography of useful textbooks and reference books used by the author will be listed at the end of this paper.
MEMS Design Education by Case Studies
Authors: Pryputniewicz Ryszard J. 
Published: November 2021

Abstract
Advances in microelectromechanical systems (MEMS) technology are based on understanding of the issues involved in design, analysis, fabrication, characterization, and use of the finished products. Although this understanding is being developed “on the job” to satisfy immediate needs of rapid advances in the emerging MEMS technology, there is also growing demand for “academic” education in MEMS. Whether on-the-job or academic, development of the required understanding is no easy task because the MEMS field is very multidisciplinary. Those involved should be able to work simultaneously with topics relating to physics, chemistry, materials, computer science, engineering, as well as other relevant disciplines. To facilitate preparation of future engineers for work with MEMS, we have developed undergraduate and graduate courses addressing some of the crucial issues relating to MEMS. These courses are based on case studies that we have developed in our laboratories. The courses include lectures, laboratory experiments, student projects, and presentations. This paper describes selected case studies used in our courses as they relate to design education with MEMS.
Wilbur and Orville Wright and the Evolution of Efficient Aircraft Propellers
Authors: Ash Robert L. , Miley Stanley J. , Landman Drew , Hyde Kenneth W. 
Published: November 2021

Abstract
Four Wright brothers’ propellers have been carefully reproduced by The Wright Experience for the purpose of measuring their performance using modern instrumentation. Reproductions of a 1903 Flyer propeller, a 1904 ‘Le Mans’ propeller, and two circa 1910 ‘bent end’ propellers have been manufactured, duplicating materials, construction and dimensional geometry. As evidenced by the correlation between static thrust measurements reported originally by the Wright brothers and our recent measurements in Old Dominion University’s Langley Full Scale Tunnel, the propeller reproductions match the static thrust performance of the original propellers to within experimental accuracy. Using modern instrumentation, it has been possible to measure the overall performance of these propeller reproductions covering their full speed ranges. Our tests have shown that the 1903 Wright propeller had a peak efficiency greater than 80 percent (Wilbur appears to have estimated its efficiency to be 66 percent) and the 1904 and 1910 propellers had peak efficiency levels approaching 90 percent. Not only did the Wright brothers’ propellers exhibit systematic increases in static thrust, but their propeller designs were extraordinary because they produced efficiencies approaching the levels found on modern-day human-powered flying machines. Our measurements have shown that the Wright brothers’ use of large-diameter, slowly rotating propellers enabled them to achieve propulsive efficiencies that were unsurpassed for nearly 20 years.
A Study of Early Stage Self-Loosening of Bolted Joints
Authors: Jiang Yanyao , Huang Bin , Zhao Hua , Lee Chu-Hwa 
Published: November 2021

Abstract
Both experimental investigation and finite element analysis were conducted to explore the mechanisms of the early stage self-loosening of bolted joints under transverse cyclic loading. The nuts were glued to the bolts using a strong thread locker in the self-loosening experiments to ensure that no backing-off of the nut occurred. Depending on the loading magnitude, the clamping force reduction ranged from 10% to more than 40% of the initial preload after 200 loading cycles. Three-dimensional elastic-plastic finite element analysis was conducted with the implementation of an advanced cyclic plasticity model. The finite element results revealed that the local cyclic plasticity occurring near the roots of the engaged threads resulted in cyclic strain ratchetting. The localized cyclic plastic deformation caused the stresses to redistribute in the bolt, and the result was the gradual loss of clamping force with loading cycles. The finite element results agreed with the experimental observations quantitatively. Both experiments and finite element simulations suggested that the friction between the clamped plates has an insignificant influence on self-loosening.
Noninvasive Measurements and Computational Modeling of SMT Assemblies
Authors: Pryputniewicz Ryszard J. , Rosato David , Furlong Cosme 
Published: November 2021

Abstract
Differential thermal expansions cause strains in the interconnection structures, during functional operation of active devices. To evaluate these strains, temperature profiles of the interconnected components must be known. In this paper, a methodology for developing thermal models of surface mount technology (SMT) assemblies is presented using thermal analysis system (TAS) and its application is demonstrated by simulating thermal fields of a representative package. Thermomechanical deformations of the package are measured quantitatively using state-of-the-art laser-based optoelectronic holography (OEH) methodology. Results of TAS simulation show good correlation with noninvasive full-field-of-view OEH measurements of thermomechanical field effects of the SMT assembly under actual operating conditions.
DSC, TMA, DMA, and TGA of Epoxies for Fiber-Optic Transceiver Applications
Authors: Lau John , Erasmus Steve , Sporon-Fiedler Fred , Chang Chris 
Published: November 2021

Abstract
The curing conditions (such as temperature and time) and material properties such as the TCE (thermal coefficient of expansion), Tg (glass transition temperature), storage modulus, tangent delta (tan δ), and moisture absorption of two different epoxy materials from two different vendors are measured. Emphasis is placed on specimen preparations, experimental procedures, and data analyses. The methods and results presented herein should be useful for evaluating epoxies for fiber-optic transceiver applications.
Periodic Homogeneization Techniques As a Way to Account for Surface Roughness in a Confined Air Flow
Authors: Bourgin Patrick , Boutaous M’hamed , Woehl Pierre 
Published: November 2021

Abstract
The motivation of the study is concerned with high speed winding of plastic films (i.e. PET). During this process, some air is entrapped between the first wrap and the roll being wound. It is well known that the residual air layer between the plastic layers has a strong influence on the internal stress state within the roll. The surface roughness of the film plays an important role on these aerodynamic effects and consequently on the internal stress. Nevertheless, the mechanisms involved are not clarified yet.
As a first step, an experimental study was conducted with the aim of characterizing the global flow kinetics of an air layer squeezed between a plastic film sample and a smooth substrate. In so doing, a new parameter was defined: some sort of a “dynamic roughness coefficient”. Nevertheless, the correlation between this parameter and those which describe the topography of a film surface (static) needed to be established.
Using the tools of 3D roughness measurements, it was observed that the heights of the peaks and the mean distances between them are of the same order of magnitude as the average distance between the opposite surfaces. We therefore assimilated the surface topography to a periodic array of cylinders of known dimensions, their spatial period and their height being of the same order as the interlayer distance. In such conditions, the air flow squeezed in the space confined between the two surfaces is studied by using an approach based on periodic homogeneization techniques.
The first tendencies indicate that a good qualitative agreement exists between the global experimental data and the theoretical results.
Recirculating Turbulent Flows of Thixotropic Fluids
Authors: Pereira Américo S. , Pinho Fernando T. 
Published: November 2021

Abstract
An aqueous suspension of 1% by weight laponite was investigated in terms of its rheology and hydrodynamic behaviour in a sudden expansion flow. The fluid was shear-thinning, thixotropic and had an yield stress which was measured by direct and indirect methods. The oscillatory tests showed that the elasticity of the 1% Laponite suspension was very small.
The high Reynolds number turbulent flow downstream of a sudden expansion, with fully-developed inlet conditions, showed no major difference in relation to the flow of water. There were no differences between the laponite and water mean and turbulent flow characteristics upstream and downstream of the expansion plane, except for a small anticipation of the loci of maximum Reynolds stresses with the suspension, but this had no further consequence.
In conclusion, although the laponite suspension was thixotropic, shear-thinning and viscoplastic, its hydrodynamic behaviour in a sudden expansion was akin to that of water, a result which could not be anticipated.
Instabilities of Numerically Computed Thermocapillary Flows in Liquid Bridges at Medium Prandtl Numbers
Authors: Hirsch Charles , Dinescu Cristian 
Published: November 2021

Abstract
The instabilities of the thermocapillary flows in cylindrical liquid bridges are investigated numerically by employing a finite volume approach to solve the complete Navier-Stokes equations accompanied by appropriate boundary conditions on the free surface, which model the surface tension effects.
The influences of Marangoni number, aspect ratio A and gravity on the computed spatio-temporal structures of the thermocapillary flow are emphasized.
The structures associated with high Marangoni number regimes are analyzed by using specific tools of the nonlinear dynamics: temperature signal, power spectrum, first return maps and Poincare maps.
The Application of PIV in the Study of Impeller-Diffuser Interaction in Centrifugal Fan: Part I — Impeller-Vaneless Diffuser Interaction
Authors: Mekhail Tarek , Li Zhang , Zhaohui Du , Jansen Willem , Hanping Chen 
Published: November 2021

Abstract
The PIV (Particle Image Velocimetry) technology is a brand-new technique of measuring velocity. It started in the 1980’s with the development of high-speed photography and the image processing technique of computers. This article deals with PIV applied to the study of unsteady impeller-vaneless diffuser interaction in centrifugal fen. Experiments were carried out at The Turbomachinery Laboratory of Shanghai Jiaotong University. The test rig consists of a centrifugal, shrouded impeller, diffuser and volute casing all made of plexiglass. A series of performance measurements were carried out at different speeds and different vaneless diffuser widths. PIV measurements were applied to measure the unsteady flow at the exit part of the impeller and the inlet part of the diffuser for the case of the same width vaneless diffuser. The absolute flow field is measured at medium flow rate and at maximum flow rate. It is informative to capture the whole flow field at the same instant of time, and it might be more revealing to observe the unstable flow in real time.
The Application of PIV in the Study of Impeller-Diffuser Interaction in Centrifugal Fan: Part II — Impeller-Vaned Diffuser Interaction
Authors: Mekhail Tarek , Li Zhang , Zhaohui Du , Jansen Willem , Hanping Chen 
Published: November 2021

Abstract
The real flow inside a turbomachinery passage is unsteady and strongly affected by wakes between stator and rotor. The aim of this study was to help our understanding of the complex unsteady flow associated with the interaction between the impeller and its vaned diffuser of a centrifugal plexiglass fan where the number of impeller and diffuser blades are 13 for each. The purpose of this paper is to present the first trial of measuring the instantaneous whole field in a part of the impeller and diffuser together at different relative locations between them. The velocity measurements utilizing a PIV system from Dantec Measurement Technology were performed. The measurements were performed at medium, maximum and minimum flow rate, near the hub, the middle and near the shroud. The Laser sheet is adjusted to go through the outer casing, the diffuser and to reach the impeller blades. The instantaneous whole field velocity measurements were taken at the exit half of the impeller and the inlet half of the diffuser including the vaneless space before the diffuser blades. The absolute radial and circumferential velocities are measured. The unsteady interaction between the impeller and vaned diffuser was measured at different relative positions between the impeller and diffuser. Further analyses concerning the relative velocity, streamlines and vorticity are also presented.
On Dynamic Pressure Measurement of Hydraulic Return Line
Authors: Koivula Timo S. , Ellman Asko U. , Vilenius Matti J. 
Published: November 2021

Abstract
Rapidly fluctuating flow conditions exist in various fluid power applications. Particularly, in return lines of fast on-off valves, circumstances are very demanding as rapidly changing flow rate causes large pressure variations and cavitation downstream from the valve. Pressure measurement of such flow conditions is diverse. In order to exploit the measured data, the measurement equipment and methods have to be reliable.
In this paper, several aspects affecting on dynamic pressure measurement in hydraulic return lines are dealt with. Suitability of several transducer types for such dynamic measurements is studied. The effects of various mounting methods and transducer orientations are studied as well.
Considerable differences in pressure responses were found with various transducer types. In addition, mounting method and restrictors in mounting fittings were found to be significant. Cavitation was found to be present in the return line and it affected measured responses. In the paper, pressure responses acquired with various pressure transducers and mounting scenarios are presented. The effects of mounting scenarios and orientation of transducers are discussed and measured responses are presented.
Simulation of Fluid Power Components Using DSHplus and ADAMS
Authors: Deeken Michael , Murrenhoff Hubertus 
Published: November 2021

Abstract
Efficiency improvement of an axial piston pump or motor is an important part in the design and development process. The behaviour of an axial piston pump or other displacement machines is a complex interaction between tribology of sliding contacts, pressure gradient in hydraulic volumes and dynamics and kinematics. Simulation programs are useful development tools to design these fluid power components on digital computers. At present all these programs are stand-alone tools and specialised to calculate a specific behaviour or effect of an axial piston pump or motor. To reproduce and to solve all this physical effects numerically in one program is impractical. Since the opportunity exists to couple standardised products, this is a promising approach.
The paper presents a simulation approach of a displacement machine (axial piston pump in swash plate design) using two different kinds of simulation programs. The tribology, e.g. surface roughness, mixed lubrication and contact pressure, and the hydraulic, e.g. the computed pressure gradient and flows, are calculated numerically by means of DSHplus. The integration of all kind of forces and torque, e.g. mass moment of inertia and pressure forces, to solve the equation of motion is calculated with a multiple body simulation program, in this case ADAMS by Mechanical Dynamics.
The flexible modelling of mechanical structures in ADAMS makes it possible to create various simulation models of motion, such as cylinders and valves. The mechanical simulation program is coupled with the hydraulic simulation program DSHplus. Both programs run simultaneously on PCs and exchange data in discrete simulation time intervals.
Modeling and Measurement of Pressure-Dependent Junction-Spreader Thermal Resistance for Integrated Circuits
Authors: Zhou Peng , Goodson Kenneth E. 
Published: November 2021

Abstract
The junction-spreader thermal resistance is an important part of the overall junction-ambient thermal resistance in electronic packages. Past research has provided theoretical models for contact thermal resistance between the thermal interface material (TIM) and the contacting rough solid surface. However, these models are based on steady-state assumptions and do not describe the evolution of the junction-spreader thermal resistance during the lifetime of an electronic package. This chapter presents a transient model for the junction-spreader thermal resistance based on classical theories for lubrication and surface wettability. This transient model provides a simple relationship for pressure-dependent junction-spreader thermal resistance and yields an optimum filler volume fraction for particle filled TIMs. An experimental approach developed in this chapter measures the pressure-dependence, as well as the spatial distribution of junction-spreader thermal resistance. The data agree reasonably well with the model predicting for the pressure-dependent junction-spreader thermal resistance. The theoretical and experimental approaches developed in this study are promising tools for thermal management and reliability engineering of electronic packaging.
Adaptation of Aerospace Cool-Suit Technology to Treatment of Multiple Sclerosis Symptoms
Authors: Emerton K. B. , Cooke W. H. , Nelson D. A. 
Published: November 2021

Abstract
Some symptoms of Multiple Sclerosis (MS) are mitigated by lowering the patient’s core temperature. Personal cooling garments, similar to those developed for cooling crewmembers in military aircraft, have been developed and marketed for the treatment of MS symptoms.
This study investigated the effectiveness of a water-cooled vest in reducing the skin surface and core (rectal) temperatures in healthy male subjects. Results show no effect on core temperature, and modest increases in skin temperature over a 30-min session. It is not known whether similar results would obtain with healthy female subjects, or with MS subjects of either gender.
Improvements for the Ford Mustang Braking System
Authors: Lambert Jon G. , Zahraee Mohammad , McIndoo Keith A. 
Published: November 2021

Abstract
Historically, the Ford Mustang is America’s favorite “Pony Car”. A Pony Car by definition means an economical sports car. However, this economical sports car is required to compete against automobiles like the Corvette and Viper in many racing circuits. In order to better compete; Mustangs must be modified, often heavily, from their showroom stock condition.
Modifications to the Mustang’s braking system are limited to what is available in the Mustang aftermarket. As such, the aftermarket has yet to address two common weaknesses in the Mustang’s braking system. They are: a lack of a front disk cooling device, and rear brakes that utilize disks larger than 11.65 inches in diameter.
This paper discusses the design, fabrication, and testing of prototype parts to eliminate these two weaknesses in the Mustang’s braking system.