bluuebunny/crossref_metadata_2025 huggingface dataset:
A Multi-Factor Interaction Model (MFIM) for Damage Initiation and Progression
Authors: Chamis Christos C. , Minnetyan Levon
Published: November 2021

A Multi-Factor-Interaction-Model (MFIM) is briefly described to represent complex point material behavior in a single equation. The model is of product form in order to represent coupled interactions and to be computationally effective. The model describes a continuum or surface in space that represents the complex material behavior in terms of the various factors that affect a specified material behavior. The material specified behavior is inclusive of all material properties, mechanical, thermal, physical and effects thereon, such as temperature, time, cyclic loadings, etc. Sample cases results simulated by using MFIM are compared with test data to illustrate its versatility and its relevance to reality. These results show the MFIM can accurately predict metal matrix composite fatigue data and mechanical properties of a steel alloy. MFIM predicted results for the damage tolerance of a large shell made from structural steel subjected to internal pressure. Helpful guidelines for its effective use are also included.
Dynamic Mode I Fracture Toughness Test of Composites Using a Kolsky Bar
Authors: Sun C. T. , Han C.
Published: November 2021

Mode I dynamic delamination fracture was studied with two polymeric fiber reinforced composites. Wedge insertion fracture test on a Kolsky bar (or split Hopkinson pressure bar) apparatus was conducted. A speed about 1,000 m/s of Mode I delamination crack propagation was achieved using high rates of loading. Dynamic fracture and crack propagation were modeled by the finite element method. Dynamic initiation fracture toughnesses of both composites S2/8552 and IM7/977-3 were obtained. For IM7/977-3, dynamic fracture toughness of IM7/977-3 associated with the high speed of propagating crack was examined. It is found that the dynamic fracture toughness of the delamination crack propagating at speed up to 1,000 m/s approximately equals to the dynamic initiation fracture toughness, which is again approximately equal to the static fracture toughness.
Dynamic Fracture Behavior of Syntactic Epoxy Foams: Optical Measurements and Analysis
Authors: El-Hadek Medhat A. , Tippur Hareesh V.
Published: November 2021

Dynamic fracture behavior of syntactic foams made of thin walled microballoons dispersed in epoxy matrix is studied. Monotonic reduction in dynamic Young’s modulus with increasing volume fraction of microballoons is observed using ultrasonic pulse-echo and density measurements. The measurements are also in good agreement with the Hashin-Shtrikman lower-bound predictions for elastic porous solids. Dynamic crack initiation toughness and crack growth behaviors are examined using instrumented drop-tower tests and optical measurements. Crack initiation toughness measurements show a linear relationship with Young’s modulus over the entire range of volume fraction of microballoons studied. A proposed model based on a simple extension of micro-mechanics prediction agrees well with the measurements. The optical method of Coherent Gradient Sensing (CGS) has been used along with high-speed photography to record crack tip deformation histories in syntactic foam samples subjected to impact loading. Pre- and post-crack initiation events have been successfully captured and apparent dynamic stress intensity factor histories are extracted from the interferograms. Optically measured stress intensity factors at crack initiation and during crack growth also decrease with increasing volume fraction of microballoons. Increasing crack speeds with volume fraction of microballoons has become evident. No significant dependence of dynamic fracture toughness on crack speed is seen in any of the volume fractions studied.
Flexural Fatigue of PVC Foams
Authors: Kanny Krishnan , Mahfuz Hassan , Carlsson Leif A. , Thomas Tonnia , Jeelani Shaik
Published: November 2021

Flexural fatigue tests were performed on cross-linked PVC foams of densities in the range from 75 to 300 kg/m3 at a frequency of 3Hz and at a stress ratio, R = 0.1. S-N diagrams were generated, and the failure mechanisms were examined. The fatigue behavior was found to be similar to structural materials with a fatigue strength that decreased with increased stress and increased with increased foam density. The final failure event was catastrophic due to crack propagation initiating at the tension side of the beam. SEM analyses of unfailed and failed 300kg/m3 density foam specimens revealed cell wall cracking and densification of the foam. The densification contributed to stiffening of foam specimens. Viscoelastic parameters of the foams were determined at room temperature using a Dynamic Mechanical Analyzer (DMA) over a frequency range of 1–10Hz. For the virgin specimens it was found that the viscoelastic moduli and damping ratio were quite independent of frequency over this range of frequencies. Except for the lowest density foam (75kg/m3), the damping ratio was quite independent of foam density.
The Effect of Stitching on Compression Behavior of Stiffened Composite Panels
Authors: Suh Sung S. , Hahn H. Thomas , Han Nanlin , Yang Jenn-Ming
Published: November 2021

Failure of stiffened panels under compression is preceded by buckling of their skin and hence is affected by the presence of out-of-plane stresses. One of the promising methods of preventing premature delamination is stitching. The present paper discusses the effect of such stitching on compression behavior of blade-stiffened panels that were fabricated from plain weave AS4/3501-6 through resin film infusion process. Kevlar 29 yarn was used at a stitch density of 9.92 stitches per cm2. Some of the panels were damaged by drop-weight impact before compression testing. For comparison purposes unstitched panels with the same materials and dimensions were also tested under the same loading conditions. Stitching resulted in a 10% improvement in strength in the absence of any intentional damage. The beneficial effect of stitching was most obvious when the panels were impacted on a flange: a 50% improvement was observed in post-impact strength. However, stitching could not prevent stiffener from failure when impacted directly. Thus stitching had no beneficial effect when impact occurred on a stiffener. A buckling and post-buckling analysis was carried out using 3-D shell elements on the Abaqus. Predictions were in fairly good agreement with the experimental data.
Damage Control in Composite Laminates
Authors: Suvorov Alexander P. , Dvorak George J.
Published: November 2021

Several effects that fiber prestress may have on stress redistribution in the plies of composite laminates and in the phases of individual plies are illustrated. These include improvement of composite damage resistance under tensile mechanical loads, reduction/cancelation of interlaminar stresses at free edges of composite laminate subjected to thermomechanical loading, and stress relaxation in the matrix phase of viscoelastic composite laminates. Specific results are found for quasi-isotropic and cross-ply symmetric S-glass/epoxy and carbon/epoxy AS4/EPON 828 laminates.
Influence of Chassis and Driveline Components in Vehicle Frontal Crash
Authors: Saha Nripen K. , Bhojan Rabin
Published: November 2021

With increased focus on new vehicle crash safety, vehicle structures are being developed to sustain more demanding frontal crash conditions such as, offset, angular, and pole impacts. To manage the higher amount of impact energy, vehicle body components are designed for higher strength and stiffness resulting in increased vehicle weight. As an alternative, a more efficient design concept involving the chassis, suspension and driveline components are studied here. Attempts are made to investigate how the non-body structure components of a vehicle can be deployed to absorb crash energy that may lessen the demand on the body-in-white. Contribution of underbody chassis subframe & cross-members, the suspension control arms and the drive-shaft components are evaluated using analytical methods for effective use in frontal impact conditions. Ideas are explored to improve the vehicle crash pulse and reduce passenger compartment intrusions in frontal impacts by employing sub-frame, drive shaft and suspension control arms more effectively.
Safety Aspects Related to the Development of a Full Aluminum Frame for the Year 2000, 1500 Series Chevy Suburban
Authors: Marshaus Julie G. , Gall Mike A. , Topinka Jennifer A. , Bower Glenn R.
Published: November 2021

In conjunction with the FutureTruck collegiate design competition, The University of Wisconsin - Madison has integrated an all aluminum frame into their four-wheel drive, charge sustaining, parallel hybrid-electric sport utility vehicle. The base vehicle is a 2000 Chevrolet Suburban nicknamed the “Moollennium” and weighs approximately 2400 kg. The original GMT 830 frame constitutes 10% of the Suburban’s weight and has the largest weight reduction potential. In a cooperative effort with Tower Automotive, the University of Wisconsin-Madison has modeled, stamped and constructed two full aluminum frames using the GMT 430 tooling. The first frame, the UW 430 AL, was assembled to replicate the GMT 430 frame, while the second-generation frame, the UW 830 AL, mimicked the GMT 830 frame. FEA and traditional deflection and bending calculations were used to stiffen and strengthen the aluminum frame to acceptable levels. Front horn crush tests were used to optimize frontal impact energy absorption — the UW 830 AL design absorbs 36% more energy than the original GMT 430 steel frame with a 40% reduction in peak load. The complete aluminum frame weighs 120 kg — 98 kg lighter than the steel GMT 830 frame and 130 kg lighter than the steel GMT 430 frame.
Crashworthiness Design Optimization of Energy-Absorbing Rails for the Automotive Industry
Authors: Kurtaran Hasan , Omar Tarek , Eskandarian Azim
Published: November 2021

Optimum crashworthiness design of the vehicle rail structure is one of the crucial tasks in designing crashworthy vehicles that render better occupant protection. The usual trial-and-error approach in selecting the optimum design parameters, in order to maximize the energy absorbing capacity of the rail structure, is computationally expensive and cumbersome; particularly when there are several design parameters to be properly selected. Optimization methods can be used to automate the search for the optimum design parameters.

In the current research, an efficient design optimization methodology is presented and utilized to obtain optimum crashworthiness design of the energy-absorbing rail structures. The methodology adopted in this research makes use of Design of Experiments (DOE) based approximation methods, numerical optimization algorithms and structural analysis software. The design optimization approach has been devoted to structural impact applications.

The nonlinear explicit Finite Element (FE) code LS-DYNA was used to conduct the rail impact problems and generate the energy function to be maximized. Several design parameters have been proposed and used to optimize the rail structure. The results indicated the promising capabilities of the developed methodology for design optimization of the energy-absorbing rails in automotive industry.
Structural Topology for Crashworthiness Design by Matching Plastic Strain and Stress Levels
Authors: Soto Ciro A.
Published: November 2021

This paper presents a new formulation for the structural topology optimization problem under crashworthiness conditions. The objective of the optimization problem is to match levels of plastic strain and stress to prescribed values while having a weight constraint under consideration. The problem is solved by using a non-gradient based algorithm that allows to reach near to the optimum in a quick fashion. An example is presented to illustrate the optimization formulation. Results show that the formulation and algorithm are suitable for practical applications.
Functional Design Tree for Mechatronic Projects in Mechanical Engineering Design Course
Authors: Korkmazel Meltem , Erden Abdülkadir
Published: November 2021

The functional approach utilizes a ‘Functional Design Tree’, which is a decomposition hierarchy of functions involving sub-functions of an engineering system at various levels of resolution. Use of functional approach in the design of mechatronic systems is investigated in the senior level mechanical engineering design projects. A survey is conducted on the senior mechanical engineering students after an engineering design course. It is attempted to find out whether the students followed the systematic design approach, and to what extent they used the functional design tree. The results of the survey are presented and evaluated in the paper, and some conclusions are derived for possible outcomes of the survey.
Evaluation of a Failure in a Chlorine Production Facility
Authors: Andrew Stephen P. , Caligiuri Robert D. , Eiselstein Lawrence E. , Parnell T. Kim
Published: November 2021

A process upset at a chlorine production facility resulted in a release that forced the partial evacuation of a nearby town. Investigations revealed that the events commenced with the failure of a shell and tube heat exchanger (liquefier) used to condense chlorine gas. Post-incident inspections revealed a cloth at the liquefier coolant inlet that accelerated the flow in that region, causing certain tubes to be breached. As a result, the water-based brine liquefier coolant was entrained in the chlorine process stream, forming a highly acidic oxidizing mixture. This corrosive mixture then flowed to the chlorine storage tanks destroying an elbow in the tank inlet piping and rendering the tank shut-off tank valve ineffective, thus allowing chlorine to vent into the atmosphere.

This paper discusses the multi-disciplinary approach used to investigate this incident. In particular, this paper discusses the detailed physical inspections performed, the finite element analyses used to determine the flow conditions, and the corrosion testing conducted to evaluate the failure.
Calculation of Nuts Threads Stripping
Authors: Martinez-Martinez Manuel , Ferrand André , Guillot Jean
Published: November 2021

In this article, we describe the development of a precise analytical model allowing to estimate the thread stripping of nuts. Initially, we carried out a modeling by finite elements of the threads stripping using an axisymmetric model and a criterion of rupture by damage. This modeling enabled us to study the various parameters which influence the behavior of a threaded assembly. To do so, we established an experimental design to know the most significant parameters. The result enables us to propose a simple rule for the optimization of the threaded assemblies whatever metallic materials of bolt and nut. We carried out tests of nuts threads stripping in order to validate this model. The estimated results are very close to those obtained by the tests.
Failure Prevention in Fiber Reinforced Composite Materials
Authors: Merodio J. , Sancibrian R. , Viadero F.
Published: November 2021

The study focuses on instabilities for fiber-reinforced nonlinearly elastic solids under plane deformations. The plane of deformation contains the fiber reinforcement. In particular, fiber kinking and fiber debonding instabilities in fiber-reinforced composite materials are examined in terms of the anisotropic character of the material models. The material models consider simultaneously the material anisotropy and the nonlinear performance of the fiber reinforced materials. Fiber kinking is captured under fiber compresion. Fiber debonding is captured under shearing deformations in the fiber direction.
Microtensile Methodology for Mechanical Characterization of Thin Films
Authors: Yeung Betty H. , Lytle Bill , Sarihan Vijay , Read David T. , Guo Yifan
Published: November 2021

A microtensile methodology developed at the National Institute of Standards and Technology (NIST) has been adopted and applied at Motorola to evaluate material properties of thin films. This methodology is a significant part of the materials technology development at Motorola. Special specimens of thin metal films are designed and produced based on common microlithographic techniques and silicon processing methods. The experimentation is performed using the microtensile tester, which was developed for the accurate measurement of constitutive properties of thin metallic films. Through the application of the techniques presented here, valuable information and results have been achieved, which provide an extended information base for thin-film materials. Ultimately, such data are applied to processing and reliability predictions and the optimization of thin-film processes and materials.
New Hybrid Methodology for the Development of MEMS Multivariable Sensors
Authors: Pryputniewicz Emily J. , Angelosanto John P. , Brown Gordon C. , Furlong Cosme , Pryputniewicz Ryszard J.
Published: November 2021

Using recent advances in microelectromechanical systems (MEMS) technology, a new multivariable sensor was developed. This MEMS sensor, capable of measuring temperature, absolute pressure, and differential pressure on a single chip, is particularly suitable for applications in process control industry. However, functional operation of the sensor depends on validation of its performance under specific test conditions. We have developed a hybrid methodology, based on analysis and measurements, that allows such validation. In this paper, the MEMS multivariable sensor is described, the hybrid methodology is outlined, and its use is illustrated with representative results.
Dynamic Characterization of Shape Memory Alloys for Integration With Electronic Packaging
Authors: Mizar Shivananda P. , Pryputniewicz Ryszard J.
Published: November 2021

Integration of Shape Memory Alloys (SMAs) with electronic packaging depends on detailed knowledge of thermomechanical behavior of SMAs. In this paper, thermomechanical behavior of SMAs is studied using a new approach based on Analytical, Computational, and Experimental Solutions (ACES) methodology. More specifically, variation in modulus of elasticity of equiatomic NiTi alloy is studied, as a function of temperature. The results show that the modulus of elasticity of the NiTi alloy studied herein varies from 38 GPa to 72 GPa as the temperature changes from −15°C to 190°C, corresponding to phase transition from martensite to austenite. Comparison of analytical, computational, and experimental results shows good correlation.
Multi-Axial Cyclic and Monotonic Behavior of a 63Sn-37Pb Solder Alloy
Authors: Lim T. Jesse , Lu Wei-Yang
Published: November 2021

In this work, the cyclic and monotonic loading of both pure torsion and uniaxial behavior of 63Sn-37Pb solder alloy are compared. By comparing the monotonic loading, it is shown that the ultimate equivalent stress of both torsion and uniaxial tensile behavior is comparable; and the failure strain in uniaxial tension is considerably less than that of pure torsion. The fatigue life of this solder alloy under the same equivalent strain amplitude for both uniaxial tension-compression and pure torsion are also comparable. These data provide a baseline for investigating the behavior of the solder alloy in the multi-axial stress-strain space.
Analysis of Thermal Stresses in a Layered Circuit Board
Authors: Gerdeen James C.
Published: November 2021

When choosing materials for a printed circuit board (PCB), it appears that a common misconception is that the coefficients of thermal expansion should be matched as closely as possible to minimize the stresses. In this paper it is shown that this is not necessarily true. A one-dimensional thermal stress analysis is considered for a printed circuit board (PCB) with N layers. Bending is neglected and average axial normal stresses and shear stresses are accounted for. It is shown that the solution for the shear stresses between layers can be written in the form of a difference equation (recurrence relation).

For the first example, a two-layer board is considered. The solution leads to a design guideline. If there is a shear stress design limit then based on this a plot can be made to choose the optimum ratio of CTEs for the layers depending upon whether the conduction heat flow q is zero or not and depending upon magnitude of temperature change.. If q = 0, then matching the coefficients of expansion α1 and α2 reduces the stress to zero. However if q is not zero at some times, then a choice of the CTE ratio α1/α2 should be made to keep the stress between the design limits.

For three or more layers with different properties a design optimization scheme can be used to choose values of the coefficients of thermal expansion.
Reliability of Plastic Package With Partially Exposed Die
Authors: Zhou Tiao
Published: November 2021

Reliability issues are discussed for a plastic laminate-based package with partially exposed die active area. Thermal-mechanical stresses are calculated with finite element analysis to examine the effect of encapsulant in comparison with a similar package with die fully encapsulated. Different material and geometry configurations are studied to assess the optimization of the package design.
Drag Reduction of the Flow Past a Circular Cylinder in Surfactant Solution
Authors: Ogata Satoshi , Watanabe Keizo
Published: November 2021

The flow around a circular cylinder in surfactant solution was investigated experimentally by measurement of the pressure and velocity profiles in the Reynolds number range 6000 < Re < 50000. The test surfactant solutions were aqueous solutions of Ethoquad O/12 (Lion Co.) at concentrations of 50, 100 and 200 ppm, and sodium salicylate was added as a counterion. It was clarified that the pressure coefficient of surfactant solutions in the range of 10000 < Re < 50000 at the behind of the separation point was larger than that of tap water, and the separation angle increased with concentration of the surfactant solution. The velocity defect in surfactant solutions behind a circular cylinder was smaller than those in tap water. The drag coefficients of a circular cylinder in surfactant solutions were smaller than those of tap water in the range 10000 < Re < 50000, and no drag reduction occurred at Re = 6000. The drag reduction ratio increased with increasing concentration of surfactant solution. The maximum drag reduction ratio was approximately 35%.
The Lagrangian Dynamics of Steady Vortex Breakdown Bubbles
Authors: Sotiropoulos Fotis , Lackey Tahirih C.
Published: November 2021

We study the phase-space bifurcations of a simple dynamical system to elucidate the role of swirl intensity on the complexity of the dynamics of particle paths in steady vortex breakdown bubbles. We show that there is a range of swirl numbers within which very small stationary disturbances superimposed on a steady, axisymmetric, vortex breakdown velocity field could have a profound effect on the Lagrangian dynamics, leading to a rich mixture of regular and chaotic behavior. Sufficiently high swirl intensity, on the other hand, can stabilize the Lagrangian orbits and yield vortex breakdown bubbles with integrable (axisymmetric) dynamics even when the transporting velocity field is not axisymmetric. We support these findings by presenting computational results for the flow in a closed cylinder with a rotating bottom.
Difference in Critical Reynolds Number Between Hagen-Poiseuille and Plane Poiseuille Flows
Authors: Kanda Hidesada
Published: November 2021

For plane Poiseuille flow, results of previous investigations were studied, focusing on experimental data on the critical Reynolds number, the entrance length, and the transition length. Consequently, concerning the natural transition, it was confirmed from the experimental data that (i) the transition occurs in the entrance region, (ii) the critical Reynolds number increases as the contraction ratio in the inlet section increases, and (iii) the minimum critical Reynolds number is obtained when the contraction ratio is the smallest or one, and there is no-shaped entrance or straight parallel plates. Its value exists in the neighborhood of 1300, based on the channel height and the average velocity. Although, for Hagen-Poiseuille flow, the minimum critical Reynolds number is approximately 2000, based on the pipe diameter and the average velocity, there seems to be no significant difference in the transition from laminar to turbulent flow between Hagen-Poiseuille flow and plane Poiseuille flow.
Pulsatile Flow Into a 45-Degree Tube Bifurcation
Authors: Tadjfar M. , Himeno R.
Published: November 2021

In this study, we use numerical simulation to investigate the pulsatile flow into a 45°-tube bifurcation. There is a well-known analytical solution for the pulsatile flow in a straight pipe. However, to study the pulsatile flow into a branched pipe only numerical solution or experimental techniques are available. The unsteady, three-dimensional, incompressible Navier-Stokes equations are solved using a finite volume solver. A time periodic flow is established. As compared to the straight tube flow case, it is found that the introduction of bifurcation changes the periodic flow structure upstream and downstream of the bifurcation. The periodic flow in the forward flow and the reverse flow part of the cycle are very different. The forward flow part of the cycle is a problem of splitting the mother tube flow into the two daughter tubes. The reverse flow part of the cycle is the problem of two jets coming out of the daughter tubes mixing in the mother tube chamber.
Significance of Inertia in Subcompartment Analysis
Authors: Ashley G. K. , Schuh W. E.
Published: November 2021

When simulating quasi-static inter-compartment flow it is currently accepted practice to include fluid inertia effects in the compartments by extending the flow path beyond its geometrical limits. Such an extension simulates inertia by effectively adding mass to the flow path that the pressure differential between the compartments must overcome. In this paper, the effects of flow inertia are investigated by comparing results for two connected compartments using a quasi-static flow approximation that neglects inertia with results from a method of characteristics program that does include inertia. Comparison of simulations employing these methodologies can be used to assess the influence of inertia during inter-compartment flow.
Detailed Simulation of the Cochlea: Recent Progress Using Large Shared Memory Parallel Computers
Authors: Givelberg E. , Bunn J. , Rajan M.
Published: November 2021

We have developed and are refining a detailed three-dimensional computational model of the human cochlea. The model uses the immersed boundary method to calculate the fluid-structure interactions produced in response to incoming sound waves. An accurate cochlear geometry obtained from physical measurements is incorporated. The model includes a detailed and realistic description of the various elastic structures present. Initially, a macro-mechanical computational model was developed for execution on a CRAY T90 at the San Diego Supercomputing Center. This code was ported to the latest generation of shared memory high performance servers from Hewlett Packard. Using compiler generated threads and OpenMP directives, we have achieved a high degree of parallelism in the executable, which has made possible to run several large scale numerical simulation experiments to study the interesting features of the cochlear system. In this paper, we outline the methods, algorithms and software tools that were used to implement and fine tune the code, and discuss some of the simulation results.
Dynamic Analysis of Diesel Engine Common Rail Injection System: Part II — Four-Cylinder Injection System
Authors: Borghi M. , Milani M. , Piraccini M.
Published: November 2021

The paper is aimed at studying the overall dynamic behavior of the Common Rail Injection System actually used on a 4 cylinder industrial Diesel engine.

Firstly, the paper introduces the main characteristics of a lumped and distributed parameters model of the high pressure branch of an actual Common Rail System, and the main hypotheses assumed to model it using a multi-port approach code for the analysis of the dynamic response of hydraulic systems submitted to fast transients.

The model of the Common Rail System is then used to study its dynamic behavior when involved in the handling of the engine injection cycle for medium values of the crankshaft regime and for different pressure levels in the Rail. The analysis is performed applying to the injectors, to the pressure control valve and to the high-pressure pump the control strategies imposed by the Electronic Central Unit (ECU), as actually implemented into an industrial ECU for Diesel engine management.

The model reliability and accuracy are evidenced through a numerical vs. experimental data comparison, mainly in term of rail pressure dynamic behavior.

The analysis successively outlined in the paper allows to state how the hydraulic behavior of the Common Rail System interact with the electro-hydraulic injectors dynamics, and to determine the influence of this interaction on the total injected mass per cycle.
Variable Flow Internal Gear Pump
Authors: Mancò S. , Nervegna N. , Rundo M.
Published: November 2021

A variable flow internal gear pump is a fixed displacement unit where timing can be varied with respect to the gearing to reduce the net outgoing flow from the delivery volume. Usually, in IC engines lubrication, and at high engine speed, a reduction of the net outgoing flow from the pump is achieved via flow recirculation to inlet through a pressure relief valve. This obviously entails a waste of power. Before thinking of variable displacement units an intermediate step worth of consideration is represented by a variable timing yet constant displacement pump. The management of timing can follow different strategies (either in delay or in advance) and a control philosophy may be implemented whereby timing is varied based on attainment of a constant delivery pressure.

The paper, through theoretical analyses, detailed modelling and simulation of the pump unit, of timing and its control, leads to compare possible and feasible alternatives providing solid ground for screening and progressing to the manufacturing of a prototype. These steps as well as test results of the prototype are contrasted with model based predictive simulations.
Design and Control of the Hydraulic Reciprocating Pump
Authors: Guangzheng Jia , Xuanyin Wang
Published: November 2021

The reciprocating pumps are widely used for transporting fluid in oil field. The flow pulsation and pressure fluctuation in the conventional reciprocating pump with short stroke, high speed and simple harmonic motion of piston driven by crank-connecting rod mechanism are inevitable. For reducing the flow and pressure pulsation, a hydraulic reciprocating pump with the GPCM control by means of normal on-off valve is designed. In order to improve the overall pump performances and life span. fault analysis and optimized design of the pump valve are completed. The mathematical model of the asymmetric cylinder system with PCM valve control used in the hydraulic reciprocating pump is built. The digital simulation about the control system is done, and the result shows that the pulsation of pump discharge flow is improved greatly.
Effect of Particle Volume Fraction on the Thermal Conductivity and Mechanical Rigidity of Particle-Laden Polymeric Thermal Interface Material
Authors: Prasher Ravi S. , Koning Paul , Shipley James , Devpura Amit
Published: November 2021

This paper reports the measurement of the thermal conductivity of particle-laden polymeric thermal interface materials for three different particle volume fraction. The experimental data is further compared with the percolation model and effective medium theory. This paper also introduces a method of obtaining the contact resistance between the particles and the polymeric matrix by combination of percolation modeling and experimental data.

We also discuss the dependence of the mechanical response of these particle-laden polymers for different filler or particle loading. A novel mechanical length scale is defined to understand the mechanical response of these materials and is correlated to the viscosity of these materials.
Infrared Thermal Velocimetry
Authors: Chung Jaewon , Shin Youngshik , Petigrew Kenneth , Chapman Peter , Grigoropoulos Costas P. , Greif Ralph
Published: November 2021

Infrared thermal velocimetry is a new technique for the measurement of flow velocity. This non-intrusive technique was used to measure the velocity in a channel. In detail, a pulse of several milliseconds of a 5W CO2 laser generates a transient temperature response in a flowing liquid. Recording the radiative thermal images of the moving heated liquid, permitted measurement of the flow velocity. This method has powerful characteristics; a wide range of velocities may be measured and the applications include MEMS fluidic devices. In this paper, experimental results are obtained from infrared thermal velocimetry for a syringe forced flow. Numerical results for the system are presented and compared with experimental data. Phenomena which are relevant to typical MEMS thermal flow sensors are also discussed.
Temperature Difference Between the Body Core and the Arterial Blood Supplied to the Brain During Hyperthermia or Hypothermia
Authors: Zhu Liang , Bommadevara Maithreyi
Published: November 2021

In this study a theoretical model was developed to evaluate the temperature difference between the body core and the arterial blood supplied to the brain. Several factors including the local blood perfusion rate, blood vessel bifurcation in the neck, and blood vessel pairs on both sides of the neck were considered in the model. The theoretical approach was used to estimate the potential for cooling of blood in the carotid artery on its way to the brain by heat exchange with its countercurrent jugular vein and by the radial heat conduction loss to the cool neck surface. It shows that blood temperature along the common and internal carotid arteries typically decreases up to 0.86°C during hyperthermia. Selectively cooling the neck surface during hypothermia increases the heat loss from the carotid arteries and results in approximately 1.2°C in the carotid arterial temperature. This research could provide indirect evidence of the existence of selective brain cooling (SBC) in humans during hyperthermia. The simulated results can also be used to evaluate the feasibility of lowering brain temperature effectively by selectively cooling the head and neck surface during hypothermia treatment for brain injury or multiple sclerosis.
Portable Fluorometry for Kinetics Applications
Authors: Venkatapathi Murugesan , Lee Charles Y.
Published: November 2021

With the current explosion of fluorescent indicators in biotechnology, there is a need for new devices to take advantage of these developments. Most fluorometers are benchtop devices and are limited in temperature control and measurement vessels. Under cell culture conditions, these restrictions limit fluorometric experimental design. A portable fluorometer has been developed that allows fluorescent measurements under cell culture and various environmental conditions. The design of the fluorometer takes advantage of dichroic mirrors to excite and measure from the same surface and is portable to conduct kinetics experiments in incubators and refrigerators.

To test the new device, fluorescence experiments were performed to determine conversion of hydroethidine (HE) to ethidium bromide (EB), which is facilitated by reactive oxygen species. Experiments were performed at room temperature and 4°C. One half ml (at 32μM) of HE at room temperature required 80 ± 3mins (mean ± S.D) for complete oxidation. Average slope of the curve was 1.04 ± 0.05 % oxidation /min. At 4°C, the reaction times were 170± 5 mins. Average slope was 0.48 ±0.03% of oxidation/min. Experiments to determine sensitivity to concentrations were performed with comparisons to a benchtop fluorometer (Hitachi 2500). Measurement by the benchtop fluorometer read 100± 6, 33± 4, 33± 4% at concentrations of 10X, 1X, and 0.1X of the working solution respectively. For the portable fluorometer, comparable concentrations had readings of 100±2, 42.2±2.0, 24.7±2.0%, respectively. This device shows both the capabilities to distinguish kinetics at different temperatures and sensitivity to concentration differences.
Transfer Matrix Formulation With Optical Penetration for Axisymmetric Thermoelastic Wave Propagation in Films
Authors: Li Chen , Lin Jiadao , Cetinkaya Cetin
Published: November 2021

Using Laplace and Hankel integral transforms in time and the radial coordinate, a fully-coupled thermoelastic formulation based on the equation of motion and heat equation is developed to study the effects of axial optical penetration on axisymmetric wave propagation in thermoelastic layers and/or layered structures. It is demonstrated that the optical penetration has no effect on the entries of the sextic transfer matrix, however it introduces an equivalent forcing term for all state variables for both surfaces of a thermoelastic layer as opposed to the surface heating case in which the heating effect is localized in the heating volume (the thermal skin). The thickness of thermal skin depends on the light intensity modulation frequency while the optical penetration typically depends only on the wavelength of the light. This additional forcing vector is a function of the light intensity modulation frequency, the radial wave number, penetration decay rate, as well as thermoelastic material properties. Complexities in wavefields due to the nature of the forcing term are demonstrated and discussed. A thin copper layer with hypothetical penetration properties is considered for the demonstration of the current formulation.
The Investigation of Distorted and Enhanced Inlet Flow Influence on the Performance of a Centrifugal Compressor Stage
Authors: Kim Yunbae , Engeda Abraham , Aungier Ron , Direnzi Greg
Published: November 2021

The performance of a centrifugal compressor can be seriously affected by inlet flow distortions due to the unsatisfactory nature of the inlet configuration and the resulting inlet flow structure.

In the previous work, experimental tests were carried out for the comparison of a centrifugal compressor stage performance with two different inlet configurations: one of which was a straight pipe with constant cross-sectional area as an ideal model and the other is a 90-degree curved pipe with nozzle shape as an actual model. The comparative test results indicated significant compressor stage performance difference between the two different inlet configurations.

In addition, the numerical simulation part of the previous work clearly showed that the inlet flow distortion is caused by the pressure driven secondary flow developed in the curved section in the case of the bend inlet, resulting in locally concentrated incidence at the impeller inlet and thus the compressor stage performance degradation. An improved inlet model with the design method has been proposed based on the comparisons of the designated flow properties.

In the present work, further numerical simulations on the compressor stage including the impeller and the diffuser with three different inlets are carried out to investigate the performance behavior of the compressor exposed to different inlet configurations. The three different inlet systems include the original bend inlet as well as the proposed inlet model based on the developed design method.

Since the flow from the bend inlet is not axisymmetric due to the circumferential and radial distortion on the cross-section, the impeller and the diffuser are modeled with fully 360-degree passages, which accommodates the inlet flow distortion and the impeller-diffuser interaction influence on the entire flow passage of the compressor. The stage performance with the different inlet systems are evaluated and compared with the previous experimental result. The diffuser performance and the flow properties in the vaneless region are compared among those inlet models. The proposed inlet system indicated the benefit of performance improvement over the original inlet system.
The Effect of Precipitation Aging on the Mechanical Behavior and Microstructure of Aluminum-Lithium Alloys
Authors: Fragomeni James M.
Published: November 2021

The effect of variations in microstructure as a consequence of heat treating and aging on the mechanical properties of aluminum-lithium alloys was studied. The thermal treatments and composition were correlated to the microstructure and subsequent mechanical behavior of aluminum-lithium and aluminum-lithium-copper alloys that were solution heat treated and artificially aged for a series of aging times and temperatures. The underaged, peak-aged, and overaged thermal heat treatments were considered in determining the effect of the microstructure and processing on the mechanical properties. Standard ASTM tensile testing of the alloys was performed to determine mechanical properties such as yield strength, ductility, and ultimate tensile strength. Quantitative microscopy of the intermetallic precipitates was performed to related the measured deformation behavior to the microstructural features. Thus, the intermetallic precipitates in the microstructure which impede dislocation motion and control the precipitation strengthening response as a function of aging practice were measured by quantitative methods, and are the basis for controlling the mechanical behavior depending on their size distribution, average size, and interparticle spacing. The microstructure was studied, and measurements were made to determine the size, distribution, and morphology for the intermetallic strengthening precipitates as a function of the processing and composition. For the aluminum-lithium alloys studied, the primary strengthening was a direct consequence of ordered coherent Al3Li intermetallic precipitates which were uniformly distributed throughout the microstructure, which restricted the glide motion of dislocations during plastic deformation.
Design, Simulation, and Test of Variable Damped Suspensions for M-965 High CG Cars
Authors: Taillon Armand P. , Klauser Peter E.
Published: November 2021

This paper reviews design and analysis methods applied in developing a three-piece Coulomb-damped truck arrangement to meet the requirements of specification M-965. This section of the AAR standards specifies performance criteria for high center of gravity cars over twist and roll inputs. The test input is a track section with a series of staggered low joints. These act to excite car body roll. The review demonstrates that properly designed suspension and damping components, in combination with side bearings, will achieve the required performance through the life of the truck. It also demonstrates the effectiveness of accurate vehicle dynamics simulations as a conservative predictor of actual vehicle performance on perturbed track. The design and analysis methods are described in detail. Guidelines are provided to help determine appropriate suspension arrangements for high CG car applications.
Estimating Economic Benefits for Improved Bulk-Commodity Suspensions
Authors: Rownd Ken , Iler Darrell
Published: November 2021

The Association of American Railroads (AAR) has sponsored an ongoing program to solicit new suspension technologies for commodity specific freight services. The process has involved assessing needs, publishing a performance specification, soliciting new designs, computer modeling, and evaluating prototypes by test and by economic models. Since 1999, this program has focused on better economic performance for bulk commodity service.

Modest changes to familiar bulk commodity truck designs have resulted in significant economic benefits in railroad service.
2000–2001 Report of Survey Committee: Progress in Passenger Rail Vehicle and Component Engineering
Authors: Hesser Kenneth R.
Published: November 2021

This annual ASME committee report covers selected worldwide developments in passenger rail vehicles components and systems. The information contained herein was obtained from responses to survey letters sent to the manufacturers of passenger rail vehicles and components, and from a review of trade and technical publications.
New Technologies for the Railway Industry: Part I
Authors: Ahmadian Mehdi , Poynor James C. , Goncalves Fernando D.
Published: November 2021

The primary purpose of this paper is to review the fundamentals, concepts, and merits of new technologies that hold a promise for helping the railroad industry in its missions. The author hopes that this paper will be the first of a series of papers that will be devoted to reviewing new technologies that are on the horizon and can benefit the rail industry, in a manner similar to the current papers that report on the progress of different aspects of transit and passenger cars, locomotives, and freight cars. The fundamental difference between this paper and current papers is that it will be devoted to new technologies that are in a more distant horizon (10–15 years), as opposed to the more immediate future developments that are covered in current papers. The first technology that will be highlighted is the magneto-rheological (MR) technology that has received a tremendous amount of attention in the past five years in the transportation industry, in particular for automotive applications. This paper will provide an overview of MR technology and its common applications, and provide some fruits for thoughts on how MR technology can be used in the rail industry.
The genetic and epigenetic landscape of the
Arabidopsis
centromeres
Authors: Naish Matthew , Alonge Michael , Wlodzimierz Piotr , Tock Andrew J. , Abramson Bradley W. , Schmücker Anna , Mandáková Terezie , Jamge Bhagyshree , Lambing Christophe , Kuo Pallas , Yelina Natasha , Hartwick Nolan , Colt Kelly , Smith Lisa M. , Ton Jurriaan , Kakutani Tetsuji , Martienssen Robert A. , Schneeberger Korbinian , Lysak Martin A. , Berger Frédéric , Bousios Alexandros , Michael Todd P. , Schatz Michael C. , Henderson Ian R.
Published: November 2021

A closer look at centromeres

Centromeres are key for anchoring chromosomes to the mitotic spindle, but they have been difficult to sequence because they can contain many repeating DNA elements. These repeats, however, carry regularly spaced, distinctive sequence markers because of sequence heterogeneity between the mostly, but not completely, identical DNA sequence repeats. Such differences aid sequence assembly. Naish
et al
. used ultra-long-read DNA sequencing to establish a reference assembly that resolves all five centromeres in the small mustard plant
Arabidopsis
. Their view into the subtly homogenized world of centromeres reveals retrotransposons that interrupt centromere organization and repressive DNA methylation that excludes centromeres from meiotic crossover repair. Thus,
Arabidopsis
centromeres evolve under the opposing forces of sequence homogenization and retrotransposon disruption. —PJH
A dynamic duo
Authors: Wojciechowski Jonathan P. , Stevens Molly M.
Published: November 2021

Self-assembly of nanofibers facilitates the repair of spinal cord injury in mice
Perovskite retrieved from the lower mantle
Authors: Fei Yingwei
Published: November 2021

The calcium silicate compound was characterized and named as “davemaoite”
AI reveals structures of protein complexes
Authors: Service Robert F.
Published: November 2021

Software extends protein mapping to complexes that govern the breadth of cell biology