bluuebunny/crossref_metadata_2025 huggingface dataset:
Cutting Temperature Measurement During Titanium Machining With an Atomization–Based Cutting Fluid (ACF) Spray System
Authors: Hoyne Alexander C. , Nath Chandra , Kapoor Shiv G.
Published: April 2014

The poor thermal conductivity and low elongation–to–break ratio of titanium lead to the development of extreme temperatures localized in the tool–chip interface during machining of its alloys and cause accelerated tool wear. The atomization–based cutting fluid (ACF) spray system has recently been demonstrated to improve tool life in titanium machining. In order to understand the cooling and lubrication mechanism of the ACF spray system, it is important to determine the temperature gradient developed inside the entire tool–chip interface. The objective of this work is to measure the cutting temperatures at various locations inside the tool–chip interface during titanium machining with the ACF spray system. The temperature gradient and mean cutting temperature are measured using the inserted and the tool–work thermocouple techniques, respectively. Cutting temperatures for dry machining and machining with flood cooling are also characterized for comparison with the ACF spray system temperature data. Findings reveal that the ACF spray system more effectively reduces cutting temperatures over flood cooling. The tool–chip friction coefficient data indicate that the fluid film created by the ACF spray system also actively penetrates the tool–chip interface to enhance lubrication during titanium machining, especially as the tool wears.
Influence of Refiner Aluminum Titanium Boride on the ZA Alloys Processed Through Centrifugal Casting
Authors: Jyothi Pathipati Naga , Rao Agari Shailesh , Chowdiah Jagath Mandyakoppal , Channakeshavalu Korrapati
Published: April 2014

Centrifugal Cast tubes have been produced with ZA 8, ZA 12 and ZA 27 alloys with different rotational speeds of the mould (Viz. 400, 600 and 800 rpm). From the past research work, it was understood that cast tubes for ZA 8 and ZA 12 alloys with good mechanical properties were produced, with the mould rotation at 600 rpm. This observation was explained without the addition of refiners. In the present work, a uniform cylinder with good mechanical properties was produced with ZA8 alloy at 400 rpm only. This was due to the influence of refiner 1% Al-Ti-B2 along with low aluminium content and lower rotational speed of the mould. With higher rotational speeds of the mould, increase in the composition of aluminium and refiner reduce solidification rate of the melt forming irregular shaped cast tube with ZA12 and ZA 27 alloys.
Mechanical Property of CFRP by Carbon Spray Up Method
Authors: Kikuchi Tetsuo , Fudauchi Akira , Koshino Tetsushi , Narita Chieko , Endo Atsushi , Takai Yuka , Goto Akihiko , Ohtani Akio , Nakai Asami , Hamada Hiroyuki
Published: April 2014

Spray up method is one of methods for composite molding and it is traditional and common molding method that can deal with various shapes according to workmen skill. The essence of the composite molding impregnates resin to fiber;, in other words, is to substitute air included in the fiber for resin. Spray up method can spray matrix on mold together while cutting reinforcements continually, and the cutting of the reinforcement, setting up and the impregnation of the matrix are carried out at the same time. That is why working process is made efficiency and can cope with a design change easily. However, the quality of the composites depends on the techniques of workmen and the judgment with Spray up technique is too difficult, because it has not clarified that the difference of that techniques has how influence with manufactured products. In addition, in a spray up method, glass reinforcements is usually used, but carbon reinforcements is not put to practical use. High quality is required with the CFRP composite, and this is because it is thought that techniques of Spray up method does not satisfy this demand. In this study, motion analysis was used to compare the difference between Spray up techniques by expert and non-expert. Expert’s carrier of Spray up was 19 years and non-expert’s carrier was a year. Motion analysis, which is applied to various fields like sports or traditional crafts and so on, can visualize human motion. The Mac 3D System was used as equipment, since it is the most powerful tool for the motion capture and analysis particularly. The sampling rate was 60 Hz. The object of this study was to contribute that technique back to fabrication fields by analyzing and considering what was important factor. Furthermore, this trial is thought that leads to the development of new technology. As the result, the motion of expert’s lower half of body indicated different motion compared with non-expert one. Expert’s centroid moved smoothly and his motion showed constant tendency. On the other hand, non-expert’s motion was awkward in several points and his motion didn’t show the tendency like expert. Furthermore, The CFRP structures that manufactured with Spray up method are cut for the tensile testing. Tensile test were performed by using an Instron universal testing machine under a speed 1mm/min. Spray up technique is discussed based on the motion analysis method and moreover it is shown that Spray up method is useful in CFRP materials production.
Acoustic Emission Based Tool Wear Condition Monitoring While Turning Nimonic C-263 Alloy Using PVD Coated Carbide Insert
Authors: Kumar V. S. Senthil , Ezilarasan C. , Velayudham A.
Published: April 2014

Due to its ability to resist thermal fatigue and creep resistance at higher temperature, nimonic C-263 super alloy is frequently applied in the hot combustion chamber of gas turbines. By virtue of the above they induce tool wear while machining which seriously affect the life of the component, and it is a serious concern, since it is used in critical applications. To monitor the status of the tool condition, several sensors are utilised, of which acoustic emission is most widely used due to its nature of generation phenomenon. In this paper PVD coated carbide insert is utilised to conduct tool wear study through turning of nimonic C-263 super alloy. The experiments were performed at different combinations of cutting conditions. The life of the cutting tool at different cutting conditions and the tool wear mechanisms were analysed. Results revealed that acoustic signal predict the condition well and that cutting velocity play a major role in the tool wear progression. Abrasion, micro chipping and plastic deformation are observed to be the major tool wear mechanisms.
Simplified Thermo-Elastoplastic Numerical Modelling Techniques Applied to Friction Stir Welding of Mild Steel
Authors: Micallef Daniel , Camilleri Duncan , Mollicone Pierluigi
Published: April 2014

Friction stir welding is a relatively new advanced joining technique that requires minimal power input, ultimately leading to less inherent residual stresses and distortion. The process involves a spinning tool which first plunges into the surface of the, to be welded assembly and then traverses along the joint. Frictional heat is generated, softening the material at temperatures significantly below the melting temperature of the parent material. As the tool traverses along the joint at a predetermined speed, the assembly is joined by means of a plastic straining process. This advanced welding technology has been validated for various aluminium alloys but it is only recently, due to advances in tool technology, that the possibility of joining mild steel using friction stir welding has become a viable option. This study looks into friction stir welding of mild steel and develops simplified numerical methods for the prediction of thermal gradients, residual stresses and deformation. In principle the process modelling requires a multi-disciplinary approach involving coupled thermo-fluid, microstructural-structural modelling process. Much of the latest thermo-mechanical studies of friction stir welding rely on a number of over simplifications particularly related to the heat flux distribution across the tool shoulder, and also on the backing plate boundary conditions. The objective of this paper is to scrutinise the effects of modelling in more detail and establish the most important factors leading to accurate yet computationally efficient prediction of thermal gradients and inherent residual stresses. The results show that both the heat input and heat loss modelling, due to heat dissipation to the surroundings, are crucial for the determination of the final inherent welding residual stresses. The heat generated is modelled through a predefined linear heat flux variation across the tool shoulder. However if a more precise and localized residual stress information is sought, a full thermo-fluid-structural analysis is required. This is time consuming and probably does not give significant information on manufacturing optimization. On the other hand, simplified global solutions offer the possibility to optimise friction stir welding parameters and boundary conditions during the preliminary stages of the development of the fabrication procedures, at relatively minimal time and processing power. This work is financed under the European Commission in Call FP7-SST-2012-RTD-1 High Integrity Low Distortion Assembly (HILDA) project.
Dimensional and Internal Structural Design for Braided Fabric Reinforced Thermoplastic Composite
Authors: Saito Takeshi , Morimoto Ryo , Imamura Masaru , Ohtani Akio , Nakai Asami
Published: April 2014

The braided fabrics are one of the typical textiles and have been expected to be an excellent performs for the reinforcements of composite materials. Fig.1 shows schematic drawing of a braided fabric. Braided fabrics are composed of Braided Yarns (BY) oriented diagonally and Middle End Yarns (MEY) inserted into the fabric in longitudinal direction. In previous study, it was clarified that the internal structures for the braided fabric were decided with 4 parameters; area and cross-sectional shape of braiding yarns, the braiding angle and distance between braiding yarns. And it have been suggested that internal structural parameters for braided fabric reinforced composites with thermo-setting resin are possible to be predicted. However in the case of braided composites with thermoplastic resin, impregnation mechanism of thermoplastic resin with solid state is completely different from that of thermosetting resin with liquid state. In order to predict internal structures of braided composites with thermoplastic resin, it is necessary to investigate the impregnation process or mechanism of thermoplastic resin in to fiber bundles apply enough heat on thermoplastic resin to be liquid state for good impregnation especially in the case of intermediate material such as comingled yarn, and etc.

The purpose of this study is to predict the relationship between dimensional and internal structural parameters for braided fabric reinforced thermoplastic composite. The braided fabric was fabricated with intermediate material such as commingled yarns. During molding with heat and pressure, effect of molding time on the mechanism of impregnation and internal structural parameters were investigated.
Extraction and Production of Keratin-Based Nanofibers for Biomedical Applications
Authors: Jarvis David , Edwards Angela , Bhattarai Narayan
Published: April 2014

Keratin, a natural biomaterial found within the hair, nails, and epidermis of humans, has shown promise of being a useful material for tissue engineering scaffolds and drug delivery systems, due in part to its favorable biological qualities. The scaffolds generated by electrospinning are useful in proliferating cells, and can even biodegrade over time, reducing the impact on the body and not invoking any adverse tissue response. This research details the extraction process of keratin from human hair, and using electrospinning to weave the keratin into nanofibrous polymers. Using a synthetic polymer solution, for example, polycaprolactone (PCL) in trifluoroethanol (TFE), keratin was easily mixed and successfully electrospun into nanofibers. The fiber formation characteristics and nanofiber morphology was studied under a scanning electron microscope (SEM).
Variation Simulation of Welded Assemblies Using a Thermo-Elastic Finite Element Model
Authors: Lorin Samuel , Cromvik Christoffer , Edelvik Fredrik , Lindkvist Lars , Söderberg Rikard
Published: April 2014

Every series of manufactured products has geometric variation. Variation can lead to products that are difficult to assemble or products not fulfilling functional or aesthetical requirements. In this paper, we will consider the effects of welding in variation simulation. Earlier work that have been combining variation simulation with welding simulation have either applied distortion based on nominal welding conditions onto the variation simulation result, hence loosing combination effects, or have used transient thermo-elasto-plastic simulation, which can be very time consuming since the number of runs required for statistical accuracy can be high. Here, we will present a new method to include the effects of welding in variation simulation. It is based on a technique that uses a thermo-elastic model, which previously has been shown to give distortion prediction within reasonable accuracy. This technique is suited for variation simulations due to the relative short computation times compared to conventional transient thermo-elasto-plastic simulations of welding phenomena. In a case study, it is shown that the presented method is able to give good predictions of both welding distortion and variation of welding distortions compared to transient thermo-elasto-plastic simulations.
Multi-Criteria Optimization of Process Plans for Reconfigirable Manufacturing Systems: An Evolutionary Approach
Authors: Zahid Taiba , Baqai Aamer A.
Published: April 2014

Production systems have developed over the years due to changing environment, external and internal drivers and conditions like new technologies, developed products and customer needs. These needs were the main drivers for integrated and evolved manufacturing systems which can be more responsive and customer focused. Prototypes of manufacturing industries which have been recently introduced as flexible and reconfigurable manufacturing systems are responding to these recent needs in peculiar ways focusing not only on product design level but also on integrated manufacturing systems and process planning level. In this work, a methodology will be presented to solve the NP-Hard problem of process planning through evolutionary optimization using Genetic Algorithms (GA) to generate and then find the optimized process plan for a part or a part family. For the creation of initial population without violating the logical or geometrical constraints, a ranked matrix based on precedence would be developed that will called as precedence group matrix (PGM). Fitness will be evaluated on the basis of setup and tool change matrices thus, making it a combinatorial optimization problem. Tool approach direction (TAD) will be assigned to each operation for generation of setup change matrix. Genetic operators like crossover, mutation and selection will be revised in order to maintain geometrical and logical constraints that come across in machining of the part. Position wise exchange will be used for crossover. A novel strategy has been proposed to check the conformance of new solution after mutation. To avoid the loss of good solutions with higher fitness value, elitist model has been proposed for selection purposes. Furthermore, a technique will be presented in order to achieve reconfigurability and responsiveness to accommodate new features in the already generated process plan, thus creating a hybrid between generative and variant process planning approach.
Helicopter Fuselage Drag Amelioration Using CFD and Experiments
Authors: Batrakov Andrey S. , Kusuymov Alexander N. , Mikhailov Sergey A. , Pakhov Vladimir V. , Sungatullin Artur R. , Zherekhov Vladimir V. , Barakos George N.
Published: April 2014

In this work, experiments are combined with CFD aiming to analyze the aerodynamics of realistic isolated helicopter fuselages. For this purpose two models based on early shapes of the ANSAT helicopter were used. Both models were tested at the low speed wind tunnel of KNRTU-KAI for a range of Reynolds numbers.
Flow Through Multi-Gate Gating System: Experimental and Simulation Studies
Authors: Kambadahalli Halappa Renukananda , Chheda Udit , Bhallamudi Ravi
Published: April 2014

Industrial and research experience has shown that casting quality is significantly affected by the flow of molten metal through the gating system before entering the mold cavity. In general, slow filling can lead to cold-shut and misrun defects, whereas rapid filling can cause sand inclusions and blow holes. The gating system comprises of one or more pouring basins, sprues, runners and gates, and optionally slag traps and filters. The number, location, shape and size of these elements determine the filling sequence and flow rate of molten metal into the mold cavity. Water, whose kinematic viscosity is of the same order as common molten metals, can be used for experiments; previous studies were however, limited to two-gate systems. In this work, flow of water and LM6 aluminum alloy through a multi-gate gating system have been compared using numerical simulation. This was followed by experimental observations of water flow in horizontal modular transparent multi-gate gating system developed in the lab, which showed similar trends as the numerical simulations. A statistical analysis of variance in the results of discharge observed with different combination of open gates provided useful insights. These insights are expected to reduce the dependence on computation-intensive CFD based simulations, reducing the total time required to optimize the gating system design for a given casting.
Wear and Mechanical Properties of Aluminum Alloy Based Hybrid Composites [(SiC+Gr) and (SiC+Al2O3)] Fabricated by Friction Stir Processing
Authors: Kumar A. , Devaraju A. , Kotiveerachari B.
Published: April 2014

In this investigation, the influence of tool rotational speed on wear and mechanical properties of Aluminum alloy based surface hybrid composites fabricated via Friction stir processing (FSP) was studied. The fabricated surface hybrid composites have been examined by optical microscope for dispersion of reinforcement particles. Microstructures of all the surface hybrid composites revealed that the reinforcement particles (SiC, Gr and Al2O3) are uniformly dispersed in the nugget zone. It is observed that the microhardness is decreased with increasing the rotational speed and exhibited higher microhardness value in Al-SiC/Al2O3 surface hybrid composite at a rotational speed of 900 rpm, due to presence and pining effect of hard SiC and Al2O3 particles. It is also observed that high wear resistance exhibited in the Al-SiC/Gr surface hybrid composites at a rotational speed of 900 rpm due to presence of SiC and Gr acted as load bearing elements and solid lubricant respectively. The observed wear and mechanical properties have been correlated with microstructures and worn morphology.
Processing and Analysis of Ceramic Mesoscale Combustors Fabricated by Co-Extrusion
Authors: Sharmin Khurshida , Schoegl Ingmar
Published: April 2014

In this work, millimeter-scale tubular combustion channels were fabricated from ceramic precursor materials. Co-extrusion of structured feedrods holds promise for the development of multi-layered, functionally graded and/or textured combustor walls, but requires a polymer binder that is difficult to remove before structures can be sintered to full density. In conventional thermal debinding, cracking is a major issue, where crack formation is attributed to a lack of pore space for outgassing of pyrolysis products. The main focus of this study is to validate a manufacturing process that uses a combination of solvent de-binding and thermal debinding, which is applied to a simple combustor geometry. Alumina powder was batched with a mixture of polyethylene butyl-acrylate (PEBA) and polyethylene glycol (PEG) in a torque rheometer. A 19mm feedrod, consisting of a carbon-black/binder mixture as core, and a surrounding ceramic/binder mixture forming the wall, was extruded through a 5.84 mm die. The binder removal involves two processing steps, where the PEG content was removed by solvent extraction (SE) to initiate pore formation, after which thermal de-binding by pyrolysis removes the remaining binder and carbon-black. Solvent extraction was performed in water at three different temperatures for various times. The 1:1 mixture of PEG:PEBA showed the highest PEG removal of 80wt% for 6 hrs extraction. The thermal de-binding cycle was designed based on thermo-gravimetric analysis (TGA) and successfully performed with a ramping rate of 1.25°C/min to 1000°C without any crack formation. After de-binding, samples were sintered at 1600°C for 1 hr. SEM analysis showed some void spaces in the solvent extracted samples but confirmed that solvent extraction followed by thermal de-binding yielded the best results. The viability of sintered ceramic tubes was tested for conditions typical for thermal cycling in a combustion environment.
Elasto-Plastic Stress Analysis of the Characteristics for T-Flange Bolted Joints Under External Loading
Authors: Omiya Yuya , Sawa Toshiyuki
Published: April 2014

In designing bolted joints, it is necessary to know the contact stress distributions in bolted joints. Recently, high strength bolts have been used with a higher bolt preload. As the results, the permanent set occurs sometimes at the bearing surfaces of clamped parts in the bolted joint. In addition, when external loads such as tensile loads, transverse loads and bending moments are applied to the bolted joint, the permanent set can be extended at the bearing surfaces. As the permanent set increases, the reduction in the bolt preload increases. Thus, it is important to estimate the reduction in the bolt preload from the reliability stand point. However, no study on the permanent set at the bearing surface under the external loading taking into account the bending moment has been carried out. In this study, the stress distribution and the extension of the permanent set at the bearing surface of the T-flange bolted joint under the external tensile loading are examined using Finite Element Method (FEM), where two T-flanges are clamped with a hexagon bolt and a nut. Using the obtained results, an increment in the axial bolt force and the reduction in the bolt preload are estimated. For verification of the FEM stress analysis, the load factor of hexagon bolt was measured. The FEM results of the load factor (the ratio of the increment in the axial bolt force to the tensile load) and the axial bolt force are in a fairly good agreement with the experimental results.
Design and Construction of a Membrane Analysis System for Fuel Cell Humidification Applications
Authors: Borduin Russell , Li Wei
Published: April 2014

Humidification membranes are vital to maintaining optimal operation conditions in polymer electrolyte membrane (PEM) fuel cells. Dry inlet air must be humidified to achieve an efficient reaction within the fuel cell. Nafion is currently the material of choice for humidification membranes due to its excellent water transport properties. However, the performance of Nafion comes at a high cost (∼ $1000/m2). There is a need to reduce membrane cost by developing an alternative material. The first step in developing a new membrane material is characterization of membrane performance. A humidification membrane measurement system was developed to determine vapor mass transfer rates through Nafion humidification membranes. The system creates a controlled environment where inlet water flow, air flow, temperature and pressure are regulated in order to measure the permeation rate of water through a membrane.
Build Direction for 3D Heterogeneous Object in Additive Manufacturing
Authors: Khoda AKM B.
Published: April 2014

Build direction in additive manufacturing is mostly determined considering the time, support materials and surface finish of the fabricated part. However, internal architecture of the part cannot be ignored in porous functional object design. Especially, heterogeneous object with internal features can be decomposed into 2D heterogeneous slices with island in which each island represent associated feature’s properties different from the base. Continuous material deposition in such multi-feature/multi-contour slices can be intervened by frequent directional changes intersecting those islands and can affect the build time and part quality. This research aims to minimize such intervention in the decomposed slices of heterogeneous object. A computational algorithm is proposed to quantify the build direction considering the location and alignment of the internal feature which can maximize the homogeneous slices generated from a heterogeneous object. The proposed methodology is illustrated by an example in this work. The algorithm can provide better control over the internal architecture design by selecting the best build direction for the heterogeneous object.
Experimental Investigation of the Tool Wear and Tool Life in Micro Hard Milling
Authors: Shashidhara Shreyas , Liu Xinyu , Zhu Weihang , Curry James , Zaloom Victor
Published: April 2014

The objective of this project is to experimentally investigate the influence of Minimum Quantity Lubrication (MQL) on tool wear and tool life in micro hardmilling. The experiments were performed on stainless steel using uncoated WC micro-mill with the nominal diameter of 508 microns. The tool wear is characterized by the volume of the material loss at the tool tip. In order to reveal the progression of the tool wear, the worn tool was examined periodically under SEM after a fixed amount of workpiece material removal (1.25 mm3 or 5 slots in this study). The tool life was characterized as the amount of material removed, instead of the conventional cutting times. The feedrate and the spindle speed were fixed, and two levels of axial depth of cut (50 and 75 microns) were compared. The higher depth of cut leads to longer tool life. The machining performance under MQL is superior to the dry machining for both process conditions in terms of the tool life. The cutting forces in feed direction and the surface roughness at the bottom of the slots were also examined during the experiments. The magnitude of the machining forces showed cyclic pattern for both MQL and dry machining. The SEM images and the cutting force signals suggested that the dominant mode of the tool wear in micro-milling is edge chipping and abrasive wear at the tool tip. The loss of the micro-grain of WC at the cutting edge leads to edge chipping, which reduces the effective cutting diameter; the abrasive wear enlarge the edge radius, causing the cutting force increase. As the cutting edge radius reaches a certain dimension, the whole edge was stripped off, a new edge formed with a smaller edge radius, and the cycle restarts. Under MQL cutting conditions, three cycles were observed before tool failure, while under dry machining conditions, the tool only experienced two cycles before tool breakage. The surface roughness at the bottom of the slots improved significantly with the application of MQL for all levels of the tool wear. The surface roughness did not increase drastically as the tool wear increased. It reached a plateau after the tool wear went into gradual wear state. Further experiments and theoretical analysis will be pursued in the future to gain a deeper understanding of tool wear mechanism in micro-milling.
Experimental Flow Field Investigations Downstream a Film Cooling Scheme Over a Flat Plate Using the PIV Technique
Authors: Hassan O. , Hassan I.
Published: April 2014

This paper presents experimental investigations of the flow field characteristics downstream a Scaled-Up Micro-Tangential Jet (SUMTJ) film cooling scheme using the Particle Image Velocimetry (PIV) technique over a flat plate. The SUMTJ scheme is a shaped scheme designed so that the secondary jet is supplied tangentially to the surface. The scheme combines the thermal benefits of tangential injection and the enhanced material strength of discrete holes schemes, compared with continuous slot schemes. The flow field characteristics downstream one row of holes were investigated at three blowing ratios, 0.5, 1.0 and 1.5, calculated based on the scheme exit area. A density ratio of unity, a Reynolds Number of 1.16E+5 and an average turbulence intensity of 8%, were used throughout the investigations. The performance of the SUMTJ scheme was compared to that of the circular hole scheme, based line case, at the same test conditions and blowing ratios. From the investigations, it was noticeable that the SUMTJ scheme jet stays attached to the surface for long downstream distances at all investigated blowing ratios. Moreover, the lateral expansion angles of the scheme help perform a continuous film from adjacent jets close to the schemes exits; however, they have bad impact on the uniformity of the film thickness in the lateral direction. The vorticity strength downstream the SUMTJ scheme in the y-z plane was much less than the vorticity strength downstream the circular scheme at all blowing ratios. However, the vorticity behavior in the shear layer between the secondary SUMTJ scheme jet and the mainstream was changing dramatically with blowing ratio. The latter is expected to have a significant impact on the film cooling performance enhancement with blowing ratio increase.
Shape Deviation Modeling for Dimensional Quality Control in Additive Manufacturing
Authors: Xu Lijuan , Huang Qiang , Sabbaghi Arman , Dasgupta Tirthankar
Published: April 2014

Dimensional quality control is critical for wider adoption of Additive Manufacturing (AM) as a direct manufacturing technology. Due to the process’ complex physics, AM-fabricated parts still require post-processing with machine tools, which significantly negates its time and cost benefits. In this paper, we investigate product shape deviation for Mask Image Projection Stereolithography (MIP-SLA) — one of the earliest commercialized AM techniques. By studying part fabrication mechanisms, we consider (i) over or under exposure, (ii) light blurring and (iii) phase change induced shrinkage or expansion as the most significant sources for shape deviations. Accordingly, the shape deviation modeling is established to quantify the effects of those influential factors and to understand the deviation mechanisms. Cylinders and cubes of various sizes were built to test our approach. Accurate prediction of shape deviation for all parts serves as a further confirmation of our model.
An Interferometer Based Experimental Technique to Evaluate Large Strains and Springback on Sheet Metal
Authors: Sanchez Luis Rafael , Peterson Shannon , Simonsen Carl G. , Satar Abrar
Published: April 2014

A technique was successfully developed to measure large tensile, compressive strains, springback and strain reversal effects on sheet metal bent to small radii. Vertical Scanning Interferometry (VSI) was used to measure three dimensional data from surfaces with sides varying from 160 nm to 2 mm. Software algorithms were utilized to determine surface topography maps from three-dimensional curved locations and to represent them in a two dimensional plane. Fine reference marks were engraved on both sides of sample. The sample was bent /unbent to small radii under a pure bending moment. Outer strains were calculated from VSI two-dimensional measurements of the original and final lengths between the reference marks. Strain gages, applied at locations close to the reference marks, gave additional information at the elasto-plastic range. Experimental data collected included bending moment as a function of strain, 3-D curvature profiles, springback and reverse bending effects. The technique was proved useful for the experimental evaluation and theoretical validation of bending and springback properties of sheet metal. Experimental results for aluminum and steel alloys are presented.
Additive Manufacturing of Conformable Electronics on Complex Objects Through Combined Use of Liquid Metal Ink and Packaging Material
Authors: Zhang Qin , Liu Jing
Published: April 2014

Conventional electronics manufacturing strategies are generally complicated, time, water, material and energy consuming. Besides, building an electronic device on a complex object generally requests a series of different connecting wires which would make the machine in a mess. Here from an alternative approach, we proposed an innovative method of realizing conformable electronic connection by the low melting point metal ink and the related flexible packaging material for quickly manufacturing electronics. The liquid metal ink could easily and directly be written on a series of complex surfaces and then coated with the packaging material which is to offer mechanical strength and prevent it from air oxygenization. For illustrating purpose, an electrical connection of LED circuit on cylindrical surface, concave, inclined structure, planes of right angle and sphere was demonstrated. Such optoelectronic device appears rather compact without any evident connecting wires exposing out. Further, a thermal cycle experiment (−40°C∼120°C) was designed to test the variation of the electrical properties of the working sample. It is disclosed that the conductive line covered by the packaging material has a temperature coefficient of 0.255 mΩ/°C (T0 = −16°C) and finally an increasing rate of only 4.24% in resistance after all thermal aging cycles. This electrical connection method is expected to have a significant impact in surface mount technology. Its applications will not only in industry but also can change the way we interact with each other and our everyday life.
Investigation of New Generation of Ceramic and Single Crystalline Piezo Materials for Helicopter Blade and UAV Actuation
Authors: Shetty Devdas , Campana Claudio , Nazaryan Nikolay , Manzione Louis
Published: April 2014

A great amount of research is being conducted to incorporate smart material actuators in aerospace applications such as (1) turbo fan engines (2) servo flap actuators for helicopter rotor control. For example, a piezoelectric stack actuator, coupled with mechanical or hydraulic amplification could provide the actuation required for the variable pitch fan system with a potentially higher level of reliability. In addition, piezoelectric actuation system could do so at a lower overall weight. However, there are limitations with existing piezoelectric stack actuators relative to power requirements. Therefore, a new approach has been investigated to improve these characteristics in order for piezoelectric stacks to be a feasible solution for these types of large scale applications. A new configuration involving dielectric, conductor, piezoelectric material in a particular sequence of stack actuation is examined and experimented. A nonlinear lumped parameter model of a piezoelectric stack has been developed to describe the behavior for the purpose of control actuation analysis.
High Accuracy, Low-Invasive Displacement Sensor (HALIDS)
Authors: Spiewak Swavik , Zaiss Curtis , Ludwick Stephen J.
Published: April 2014

Sub-micron accuracy and precision in measuring unconstrained, spatial motion is pivotal in science and engineering. It imposes stringent requirements on the accuracy, reliability, and invasiveness of sensing devices (including lasers, lidar sensors, or optical scales). While the capabilities of these devices have seen dramatic improvements in the last decades, the needs for sub-micron accuracy, low-invasive sensors greatly outpace the available solutions. The root cause of measurement difficulties is a conflict between the very nature of motion (simultaneous translations and rotations relative to a chosen reference base) and the fundamental requirement of measurement accuracy known as the Abbe principle.

Small and accurate Microsystems Technology based inertial sensors (accelerometer and gyroscopes) can alleviate, or at least significantly mitigate, many of the current difficulties. If contained in small Inertial Measurement Units (IMU) and equipped with a wireless signal transmission, they can be placed on or very close to the objects whose motion is to be measured.

Furthermore, as long as the IMU, its fixture, and some region of this object around the fixture can be considered as rigid, coordinate transformation rules facilitate converting signals measured by IMU into translations and rotations of any point in this rigid region. Consequently, a virtual 6-DOF sensor can be created. Its dimensions are infinitesimally small, and it can be “placed” anywhere within the above rigid region. In particular, it can be placed such that it is collinear with the displacements of the cutting tool or robot’s end effector, and satisfies the Abbe principle.

We present a High Accuracy, Low-Invasive Displacement Sensor (HALIDS) for application in manufacturing and in engineering design. The sensor is capable of measuring simultaneously 6-degrees-of-freedom displacements of objects. Its short term resolution is down to 0.1 nanometer and accuracy better than 1 micron. The sensor can be built small, light and wireless. Results from experimental evaluation of two prototype versions are presented.
A Numerical Investigation of Stator-Rotor Interaction Effects on Flow Field and Film Cooling Effectiveness in a 3D Transonic Turbine Stage With Highly Twisted Rotors
Authors: Xu Huazhao , Wang Jianhua , Wang Ting
Published: April 2014

To reduce aerodynamic losses and optimize turbine blade cooling designs, a comprehensive understanding of rotor-stator interaction effects on the blade aerodynamics and film cooling performance is essential. This paper focuses on the numerical analysis of the interactions between shock waves and unsteady wakes and their effects on cooling effectiveness of a highly twisted rotor within a transonic turbine stage. The parameters of the turbine stage are from the Pratt & Whitney Energy Efficient Engine (E3) program. The Realizable k-ε turbulence model was selected as the suitable turbulence model by our previous study. The investigation is conducted first by analyzing mean static pressure and the Root Mean Square (RMS) of the static pressure, followed by a detailed study of the flow field in the rotor passage at blowing ratios (Br) of 0.5, 1.0 and 1.5. Effects of the complicated interactions among shock waves, trailing edge wake shedding, and blockage of moving rotors are separated and identified individually through shock strength, vortices, and entropy production.

The results show that: 1) For the stator, the shock waves emanating from the trailing edge of the neighboring stator impinging on the later part of the stator’s suction side, creating static pressure fluctuations as large as 20%. 2) For the rotor, the variation of static pressure is synchronized with the rotor passing frequency, but out of phase between the suction and pressure sides. 3) A high entropy region generated by the wake flow from the upstream trailing edge in the rotor passage intensifies and moves towards the rotor hub during the rotor passing periods. 4) Most of the cooling air injected from the rotor leading edge bends towards the suction side, and the cooling air injected from the pressure side turns towards the rotor hub. 5) An increase in the blowing ratio from Br = 0.5 to Br = 1.5 does not affect the pressure fluctuations, but does significantly increase film cooling effectiveness on the rotor pressure side. 6) The mean static pressure on the suction side of the twist blade is lower than a straight blade, indicating the benefit of producing larger torque by using twist rotors.
Prediction of Race Performance of Elite Cross-Country Skiers by Lean Mass
Authors: Carlsson Magnus , Carlsson Tomas , Hammarström Daniel , Malm Christer , Tonkonogi Michail
Published: April 2014

Purpose:

To investigate the relationship between race performance and lean mass (LM) variables, as well as to examine sex differences in body composition in elite-standard cross-country skiers.

Methods:

Thirty-four elite cross-country skiers (18 men and 16 women) underwent a dual-emission X-ray-absorptiometry body-composition test to determine LM, fat mass, and bone mineral content. For both sexes, performance data were collected from a sprint prologue and a distance race.

Results:

The absolute expression of LM variables (whole-body [LMWB], upper body [LMUB], and lower body [LMLB]) was significantly correlated with finishing time in the sprint prologue independent of sex. Distance-race performance was significantly related to LMWB, LMUB, and LMLB in women; however, no correlation was found in men. Men had a significantly higher LM and lower fat mass, independent of expression (absolute or relative), for the whole body, arms, trunk, and legs, except for the absolute fat mass in the trunk.

Conclusions:

The absolute expressions of LMWB, LMUB, and LMLB were significant predictors of sprint-prologue performance in both sexes, as well as of distance-race performance in women only. Compared with women, male skiers have a higher LM in the body segments that are major contributors to propelling forces. These results suggest that muscle mass in the lower and upper body is equally important for race performance; thus, more focus of elite skiers’ training should be directed to increasing whole-body muscle mass to improve their competitive performance capability.
Identifying Fallers and Nonfallers With the Maximal Base of Support Width (BSW): A One-year Prospective Study
Authors: Swanenburg Jaap , Mittaz Hager Anne Gabrielle , Nevzati Arian , Klipstein Andreas
Published: April 2014

The purpose of this prospective cohort study was to determine whether the maximal width of the base of support (BSW) measure is able to predict the risk of multiple falls in community-dwelling women. Thirty-eight community-dwelling women (mean age of 72 ± 8 years old) participated. Falls were prospectively recorded during the following year. Overall, 29 falls were recorded; six (16%) women were multiple fallers and 32 (84%) were nonfallers. There was a significant difference in the BSW between the fallers and nonfallers (F[1, 37] = 5.134 [p = .030]). A logistic regression analysis indicated a significant contribution of the BSW test to the model (odds ratio = 0.637; 95% CI [0.407, 0.993]; p = .046 per 1 cm).The cut-off score was determined to be 27.8 cm (67% sensitivity and 84% specifcity). These results indicate that women with a smaller BSW at baseline had a significantly higher risk of sustaining a fall.
Arthroscopic Versus Open Matrix-Induced Autologous Chondrocyte Implantation: Results and Implications for Rehabilitation
Authors: Edwards Peter K. , Ebert Jay R. , Janes Gregory C. , Wood David , Fallon Michael , Ackland Timothy
Published: April 2014

Context:

Matrix-induced autologous chondrocyte implantation (MACI) has become an established technique for the repair of chondral defects in the knee. MACI has traditionally required an open arthrotomy, but now lends itself to an arthroscopic technique, which may decrease the associated comorbidity of arthrotomy, potentially allowing for faster rehabilitation.

Objective:

To compare postoperative outcomes between arthroscopic and open arthrotomy techniques of MACI and present a case for faster recovery and accelerated rehabilitation after surgery.

Design:

Retrospective cohort study.

Setting:

Private functional rehabilitation facility.

Patients:

78 patients (41 arthroscopic, 37 open) treated with MACI for full-thickness cartilage defects to the femoral condyles.

Intervention:

According to surgeon preference, patients recruited over the same time period underwent MACI performed arthroscopically or via a conventional open arthrotomy. Both surgical groups were subjected to an identical rehabilitation protocol.

Main Outcome Measures:

Patient-reported (Knee Injury and Osteoarthritis Outcome Score, Short Form Health Survey, and visual analogue scale) and functional (6-min-walk test, 3-repetition straight-leg-raise test [3R-SLR]) outcomes were compared presurgery and at 3, 6, and 12 mo postsurgery. Active knee range of motion (ROM) was additionally assessed 4 and 8 wk postsurgery. MRI evaluation was assessed using magnetic-resonance observation of cartilage-repair tissue (MOCART) scores at 3 and 12 mo. The length of hospital stay was evaluated, while postsurgery complications were documented.

Results:

Significant improvements (P < .05) for both groups were observed over the 12-mo period for patient-reported and functional outcomes; however, the arthroscopic cohort performed significantly better (P < .05) in active knee-flexion and -extension ROM and the 3R-SLR. No differences were observed in MOCART scores between the 2 groups at 12 mo. Patients who received arthroscopic implantation required a significantly reduced (P < .001) hospital stay and experienced fewer postoperative complications.

Conclusions:

Arthroscopic MACI in combination with “best practice” rehabilitation has shown encouraging early results, with good clinical outcomes to 12 mo, reduced length of patient hospitalization, and reduced risk of postsurgery complications. This may have important implications for postoperative rehabilitation and a faster return to full function.
To Fence or Not to Fence
Authors: Woodroffe Rosie , Hedges Simon , Durant Sarah M.
Published: April 2014

Fences must be used with care in biodiversity conservation to avoid unintended consequences.
The Gravity Field and Interior Structure of Enceladus
Authors: Iess L. , Stevenson D. J. , Parisi M. , Hemingway D. , Jacobson R. A. , Lunine J. I. , Nimmo F. , Armstrong J. W. , Asmar S. W. , Ducci M. , Tortora P.
Published: April 2014

Inside Enceladus

Saturn's moon Enceladus has often been the focus of flybys of the Cassini spacecraft. Although small—Enceladus is roughly 10 times smaller than Saturn's largest moon, Titan—Enceladus has shown hints of having a complex internal structure rich in liquid water.

Iess
et al.

(p.
78
) used long-range data collected by the Cassini spacecraft to construct a gravity model of Enceladus. The resulting gravity field indicates the presence of a large mass anomaly at its south pole. Calculations of the moment of inertia and hydrostatic equilibrium from the gravity data suggest the presence of a large, regional subsurface ocean 30 to 40 km deep.
Immune Activation with HIV Vaccines
Authors: Fauci Anthony S. , Marovich Mary A. , Dieffenbach Carl W. , Hunter Eric , Buchbinder Susan P.
Published: April 2014

Future HIV vaccine research should consider the balance between responses that favor protection and those that lead to susceptibility to infection.
A Simple Complex on the Verge of Breakdown: Isolation of the Elusive Cyanoformate Ion
Authors: Murphy Luke J. , Robertson Katherine N. , Harroun Scott G. , Brosseau Christa L. , Werner-Zwanziger Ulrike , Moilanen Jani , Tuononen Heikki M. , Clyburne Jason A. C.
Published: April 2014

Cyanide Hitches a Ride

Cyanide is a by-product of the biosynthesis of ethylene in plants and it has been somewhat puzzling how the ion is safely removed before it can shut down enzymatic pathways by coordination to catalytic iron centers. A proposed mechanism has implicated the cyanoformate ion—essentially, a weak adduct of cyanide and carbon dioxide—as the initial product, although its lifetime was uncertain.

Murphy
et al.

(p.
75
; see the Perspective by

Alabugin and Mohamed

) crystallized this previously elusive adduct and found that its solution-phase stability varies inversely with the dielectric properties of the medium. The results bolster a picture in which the adduct shuttles the cyanide away from the hydrophobic confines of the enzyme before releasing the cyanide into the more polar aqueous surroundings.
Not So Permanent El Niño
Authors: Lea David W.
Published: April 2014

Paleoclimate data point to a warm tropical ocean with a clear east-west temperature gradient during the warm climates of the Pliocene and Miocene.

[Also see Report by

Zhang
et al.

]
The Michael Jackson Fly
Authors: Mann Richard S.
Published: April 2014

A pair of neurons in the CNS of flies controls and coordinates their ability to walk backward.

[Also see Report by

Bidaye
et al.

]