bluuebunny/crossref_metadata_2025 huggingface dataset:
Efficient gene targeting and removal of foreign DNA by homologous recombination in the picoeukaryote Ostreococcus
Authors: Lozano Jean‐Claude , Schatt Philippe , Botebol Hugo , Vergé Valérie , Lesuisse Emmanuel , Blain Stéphane , Carré Isabelle A. , Bouget François‐Yves
Published: April 2014

With fewer than 8000 genes and a minimalist cellular organization, the green picoalga Ostreococcus tauri is one of the simplest photosynthetic eukaryotes. Ostreococcus tauri contains many plant‐specific genes but exhibits a very low gene redundancy. The haploid genome is extremely dense with few repeated sequences and rare transposons. Thanks to the implementation of genetic transformation and vectors for inducible overexpression/knockdown this picoeukaryotic alga has emerged in recent years as a model organism for functional genomics analyses and systems biology. Here we report the development of an efficient gene targeting technique which we use to knock out the nitrate reductase and ferritin genes and to knock in a luciferase reporter in frame to the ferritin native protein. Furthermore, we show that the frequency of insertion by homologous recombination is greatly enhanced when the transgene is designed to replace an existing genomic insertion. We propose that a natural mechanism based on homologous recombination may operate to remove inserted DNA sequences from the genome.
The location of sites and effect of semiconductor diode trans‐scleral cyclophotocoagulation on the buphthalmic equine globe
Authors: Gemensky‐Metzler Anne J. , Wilkie David A. , Weisbrode Steven E. , Kuhn Sonia E.
Published: April 2014

Purpose

To determine appropriate location and energy settings for trans‐scleral cyclophotocoagulation (TSCPC) for buphthalmic equine globes.

Animals

Eleven horses with a buphthalmic eye blinded by glaucoma presented for enucleation.

Methods

Globe and corneal dimensions were measured via ultrasonography and calipers, andTSCPCwas performed under general anesthesia immediately prior to enucleation. Part 1: In nine globes, sixty sites were lasered 4 mm posterior to the limbus in the dorsotemporal and ventrotemporal quadrants at settings of 1500 milliwatts and 1500 ms. Globes were processed and sectioned sagitally over the temporal aspect in two blocks, each with five histologic sections examined by light microscopy. A digital imaging system was used to determine the location and length of the pars plicata on one slide from each block. Part 2: Based on results in Part 1, two globes were measured and lasered using the same time and energy settings at the following distances posterior to the limbus: 8 mm dorsally, 6 mm dorsotemporally, 5 mm ventrotemporally, and 5 mm ventrally.

Results

Globe and corneal dimensions exceeded normal values in all globes. Part 1: In all nine globes, photocoagulation affected the anterior ciliary processes and iris base and in 8/9 coagulation of the pectinate ligaments was noted. Part 2: In both globes, coagulation was confined to the pars plicata.

Conclusions

The previously recommendedTSCPCsites are located too far anteriorly for a buphthalmic globe. Buphthalmic equine globes should haveTSCPCperformed at the following distances posterior to the limbus: 6–8 mm dorsally, 5–6 mm dorsotemporally, 4–5 mm ventrotemporally, and 4–5 mm ventrally.
The Use of Direct‐Fed Microbials to Reduce Shedding of Escherichia coli O157 in Beef Cattle: A Systematic Review and Meta‐analysis
Authors: Wisener L. V. , Sargeant J. M. , O'Connor A. M. , Faires M. C. , Glass‐Kaastra S. K.
Published: April 2014

Human illness due to infections with Escherichia coli O157 is a serious health concern. Infection occurs through direct contact with infected animals or their faeces, through contaminated food or water and/or through person‐to‐person transmission. A reduction in faecal E. coli O157 shedding in cattle might reduce the burden of human infections. We used systematic review and meta‐analysis to assess the efficacy of direct‐fed microbials (DFM), compared with placebo or no treatment, fed during the pre‐harvest stage of production in reducing faecal E. coli O157 shedding in beef cattle during field trials. Four electronic databases, Nebraska Beef Reports and review article reference lists were searched. A total of 16 publications assessing faecal shedding at the end of the trial and/or throughout the trial period were included. The majority of publicly disseminated trials evaluated the prevalence of E. coli O157 faecal shedding; only two evaluated the concentration of organisms in faeces. The prevalence of faecal E. coli O157 shedding in cattle is significantly reduced by DFM treatments (summary effect size for all DFM – OR = 0.46; CI = 0.36–0.60). The DFM combination Lactobacillus acidophilus (NP51) and Propionibacterium freudenreichii (NP24) was more efficacious in reducing the prevalence of faecal E. coli O157 shedding at the time of harvest and throughout the trial period compared with the group of other DFM, although this difference was not statistically significant. Furthermore, we found that the combination [NP51 and NP24] treatment was more efficacious in reducing the prevalence of faecal E. coli O157 shedding at the time of harvest and throughout the trial period when fed at the dose of 109 CFU/animal/day than any lesser amount, although this difference was not statistically significant. Feeding beef cattle DFM during the pre‐harvest stage of production reduces the prevalence of E. coli O157 faecal shedding and might effectively reduce human infections.
Experimental Investigations Into the Finishing Force and Torque in Magnetic Abrasive Finishing Process
Authors: Mulik R. S. , Pandey P. M.
Published: April 2014

Magnetic abrasive finishing (MAF) is a finishing process in which surface is finished by removing the material in the form of micro-chips by the magnetic and abrasive particles in the presence of a magnetic field. In a finishing process, forces have direct influence on the generation of finished surface and accuracy of the workpiece.

The magnitude of force or torque is also of importance as the surface integrity is affected. In the present research work, new design of electromagnet which gave relatively lesser force and torque as compared to conventional annular electromagnet was used to perform MAF. The measurements of normal force and finishing torque were carried out at different processing conditions using Kistler’s dynamometer and were found in the order of 24 N and 8 Nm respectively. The experiments were planned using Taguchi’s L16 orthogonal array and supply voltage to electromagnet, rpm of electromagnet, finishing gap and abrasive weight percentage at four levels were considered as process parameters. Supply voltage to the electromagnet and finishing gap were found to be the significant factors affecting finishing force and torque in this work. The scanning electron microscopy (SEM) study of the finished workpiece showed that there was no surface or subsurface damage due to very low finishing force and torque.
Productivity Theory for Industrial Automated Lines
Authors: Usubamatov Ryspek , Sin Tan Chan , Hamzas Mohd Fidzwan B. Md. Amin
Published: April 2014

The basic attributes of any industrial machines and systems are productivity rate and quality of products. Attributes of productivity are related to the theory of reliability let alone the theory of efficiency of machines. Publications in area of productivity of the industrial systems enable to write the productivity theory for the industrial machines and systems. This theory shows the links between productivity, reliability, technological and technical parameters and the structure of machines with complex designs. Automated production lines are considered industrial systems for the collection of serial and parallel stations arranged according to a certain structure that depends on a technological process of machining parts. Manufacturers require correct and clear mathematical models to calculate the productivity of the automated lines with high accuracy.

The mathematical models for productivity rate of industrial systems with complex design define their structures according to the level of output. This paper presents an analytical approach to the productivity rate of automated lines with stations and mechanisms that display different failure rates and processing times. The typical designs of industrial automated lines are considered by three types of structure: multi-station ’s automated line of serial, parallel action and serial-parallel action. All designs can be presented using linear, circular and rotary arrangements. The analytical equations allow for the output of the automated lines to be modeled with different failure rates for the stations and mechanisms yielding results close to the actual productivity values.
Analysis on Failure Mechanism of Scarf Joints With Brittle-Ductile Adhesives Subjected to Uniaxial Tensile Loads
Authors: Liao Lijuan , Sawa Toshiyuki , Huang Chenguang
Published: April 2014

The failure mechanism of scarf joints with a series of angles and brittle-ductile adhesives subjected to uniaxial tensile loads is analyzed by using a numerical method which employs a cohesive zone model (CZM) with a bilinear shape in mixed-mode (mode I and II). The adopted methodology is validated via comparisons between the present simulated results and the existing experimental measurements, which illustrate that the load-bearing capacity increases as the scarf angle decreases. More important, it is observed that the failure of the joint is governed by not only the ultimate tensile loads, but also the applied tensile displacement until complete failure, which is related to the brittle-ductile properties of the adhesive layer. In addition, failure energy, which is defined by using the area of the load-displacement curve of the joint, is adopted to estimate the joint strength. Subsequently, the numerical results show that the strength of the joint adopting ductile adhesive with higher failure energy is higher than that of the joint using brittle adhesive with lower failure energy.
Automation in Manufacturing Operation of Crankshaft
Authors: Jha Nand K.
Published: April 2014

This paper deals with multistage flow type manufacturing of crankshafts. The advanced methodologies in manufacturing systems, re-configurability and high speed manufacturing adopted in the paper will help reduce cost and improve productivity. The optimization of the multistage manufacturing is based on mathematical programming formulation and decomposition approach. The optimum process parameters such as speed, feed and depth of cut for individual operations are calculated using this technique. The effect of change in design data on manufacturing parameters and eventually the cost of the crankshaft at each operation are visualized. This is likely to help the manufacturing engineers to attempt to reduce cost at appropriate stage. The manufacturing automation of crankshaft is attempted on the methodology presented in the paper. The final configuration of the automated production system shows the specification of machine tools in the production system.
Product Innovation Needs Improved Design Process of Screw Joints
Authors: Friedrich C. , Hubbertz H.
Published: April 2014

An essential task in today’s engineering is to realize a multifunctional design which needs an optimization process to achieve highest performance (load profile), minimized energy consumption (fuel, gas, electricity in production and life time of product) and maximized sustainability (during entire life cycle from idea to end of life) at an affordable prize in combination. Another point is that the performance of products is increased steadily up to now, which shifts the load profile towards higher peak loads.

Consequently, a related design methodology is necessary which takes into account modern techniques of CAD (Computer Aided Design) and FEA (Finite Element Analysis) besides analytical engineering calculation and testing. Also the inclusion of nontechnical aspects must be possible (e.g. experience, rating of economy). Besides this the local stressing, time dependency and non-linear behavior must be considered in more detail; examples are proposed below.

This methodology can be illustrated very well for the example of screw joints in products with high mechanical loading between components. Established technical literature mainly refers to pure technical aspects of bolted joints, e.g. [1, 2, 3].

Another important aspect for modern products is the increased use of mechatronic functions (mechanical system added by sensors, actuators and controller as well as controlling software). These functions raise the variety of failure modes significantly, which requires improved reliability. The paper describes, how screw joints are affected, because the number of screw joints increases and that engineers have to use reliable design methods to develop robust products. Looking to the packaging of mechatronic products, smaller screws joints are used because of space restrictions coming from the high number of components. In the end this means higher stressing of smaller screws. Countersunk heads offer benefits regarding space requirements, but need to consider positioning tolerances.

For optimization process always non-linear relations are challenging; they need special description of the mechanisms and increase the demand for quality of the optimization method (e.g. convergence of numerical methods).

Conclusions from this result in fastening perspectives for the design of innovative products for the future (automation of engineering design for fast product development considering complex interactions).
Estimation of the True Interfacial Shear Strength for Composite Materials With the Microbond Test
Authors: Ash Jason T. , Kjerengtroen Lidvin , Cross William M. , Kellar Jon J.
Published: April 2014

Conservative estimates of the true interfacial shear strength (IFSS) were obtained by applying the Coulomb-Mohr failure theory to microbond test data in this combined experimental and computational study. Experimentally, interfacial strengths of unsaturated polyester on untreated and silane treated optical glass fibers were measured with an axisymmetric microbond test system. Commonly reported average IFSS values were 6.51 MPa for untreated fibers and 8.01 MPa for silane treated fibers with coefficients of variation that ranged from 9.7–22%, which was an improvement from the previous parallel blade system that ranged from 17–66%. Axisymmetric finite element analysis (FEA) was completed with the aid of a Microbond Input Generator program that reduced model development and analysis time by 97% from 1000 minutes to under 30 minutes making this feasible to perform FEA on every experimental microbond sample. FEA models include the complex microbond bead geometry, contact loading conditions, and constituent material properties measured according to ASTM standards. Application of the Coulomb-Mohr failure theory revealed a conservative estimate of the true IFSS in the absence of compressive radial stresses to be 19.2 MPa for untreated fibers and 25.1 MPa for silane treated fibers. Comparisons are also made with the maximum IFSS value.
Hybrid Additive Manufacturing of 3D Compliant Tactile Sensors
Authors: Vatani Morteza , Engeberg Erik D. , Choi Jae-Won
Published: April 2014

A resistance based conformal, compliant multi-layer tactile sensor was designed and built layer by layer using a hybrid manufacturing process. A highly stretchable, photocurable, piezoresistive sensing material was deposited on a conformal, soft molded structure using a direct printing device. The principle of the sensor is based on detecting the changes in resistance as it is deformed. The fabricated tactile sensor consists of two layers of sensing elements within the 3D skin structure where the sensing elements in the top layer are orthogonally placed atop the bottom layer. Due to the multiple layers of wires, the sensor can potentially detect various external forces/motions in two and/or three dimensions. Piezoresistivity and conductivity was introduced into the nonconductive stretchable prepolymer through dispersion of multi-walled carbon nanotubes (MWNTs). Experiments were performed to characterize the ability of the sensor to detect the location that forces were applied to the surface. Finally, it is expected that the developed conformal tactile sensor using the hybrid manufacturing method and materials could be used for various robotics and electronics applications.
Phase Transfomation Stress Field due to Hot Corrosion in the Top Coat of TBC
Authors: Abubakar Abba Abdulhamid , Akhtar Syed Sohail , Arif Abul Fazal M.
Published: April 2014

Due to the use of low quality fuels in Saudi Arabia, hot corrosion occurs at the top coat of Thermal Barrier Coatings (TBCs) as a result of the formation of a molten salt, V2O5, which penetrates it through either diffusion mechanism or the open porosities in the YSZ. The interaction between this molten salt and the Zirconia stablizer is a dissolution-precipitation type reaction which occurs throughout the Planar Reaction Zone (PRZ) and the Melt-Infiltrated Reaction Zone (MIRZ) leaching a new phase, YVO4, and also causing tetragonal to monoclinic phase transformation of Zirconia. Swelling due to transformation-mismatch plasticity causes the development of localized stresses in the topcoat which subsequently contributes to the premature failure of the coating. In the current work, a 1D-Phase field model was developed that could estimate the kinetics and micro-structural evolution during the isothermal (diffusional) tetragonal-to-monoclinic phase transformation at 900°C in the top coat. The result obtained from the Phase Field Model was sequentially coupled with Finite Element Method, and the resulting stress field in the top coat was predicted.
Temperature-Supported Forming of Automobile Related Magnesium Components
Authors: Schieck Frank , Drossel Welf-Guntram , Bräunlich Hans , Scheffler Sören , Pierschel Norbert
Published: April 2014

Lightweight design in passenger cars is gaining more and more importance. Independent from conventionally or electrically drive train concepts, weight reduction is one of the most rated defining variables for fuel or energy consumption, thus affecting the range of the vehicle. Overall, the potential for using steel in lightweight bodywork construction has attained a high level of development with the result that the potential for further optimisation is increasingly diminishing. As a consequence, alternative lightweight construction materials are set to become more important in the future.

Compared to the beneficial application potential regarding bending and distortion of steel- and Aluminium compared to Magnesium blanks, this material becomes more and more interesting for automobile applications.

Beside challenges like corrosion and recycling, mainly an appropriate forming technology lies in the focus of investigations. Due to the insufficient forming conditions of Magnesium at room temperature the focus of investigation was related to the characterisation of material properties depending on temperature, the thermo-mechanical forming simulation for process and tool design and the practical realisation of complex, car-related part geometries as well as requirements for forming tools and additional devices.

In the following article we will present the results of studies into the forming of magnesium sheets (AZ31) including tailored blanks, achieved within a growth cell (TeMaK and TeMaK+).
Thermal-Structural Design of Actively-Cooled Panels Reinforced by Light-Weight Truss Cores
Authors: Song Hongwei , Li Mingjun , Huang Chenguang , Wang Xi
Published: April 2014

This paper focuses on thermal-structural analysis and lightweight design of actively-cooled panels reinforced by low density lattice-framed material (LFM) truss cores. Numerical models for actively-cooled panels are built up with parametric codes to perform the coupled thermal-structural analysis, considering the internal thermal environment of convective heat transfer in the combustor and convective heat transfer in the cooling channel, and internal pressures from the combustion gas and the coolant. A preliminary comparison of the LFM truss reinforced actively-cooled panel and the non-reinforced panel demonstrates that the thermal-structural behavior is significantly improved. Then, an optimization procedure is carried out to find the lightest design while satisfying thermal deformation and plastic strain constraints, with thicknesses of face sheets and topology parameters of LFM truss as design variables. The optimization result demonstrates that, compared with the non-reinforced actively-cooled panels, weight reduction for the panel reinforced by LFM truss may reach 19.6%. We have also fabricated this type of actively-cooled panel in the laboratory level, and the specimen shows good mechanical behaviors.
Low Cycle Fatigue Property of Injection Molded Jute/PP Composites
Authors: Liu Xiahui , Wang Jian , Wang Cuntao , Song Weiguang , Yang Yuqiu
Published: April 2014

Green composites are biocomposites where both matrix and reinforcement derive from renewable or recycle resources and have attracted much attention in recent years. In particular, jute/polypropylene (PP) is one of the good choices of green composites. Further, investigation of long-term behavior of composite is an importance in designing in composite structures. However, so far, very few research works focus on the fatigue property of injection molded jute/PP fabricated by long fiber pellets (LFT). In this study, the pultrusion technique was adopted to prepare LFT pellets for injection molding and LFT dumbbell specimens with different jute fiber weight percent of 10, 20, 30, 40, and 50 percent were molded. Low cycle fatigue property of injection molded jute/PP composites was investigated by tensile test. Different cycle times of 30, 60 and 100 were adopted to evaluate the effect of cycle times and fiber content on the fatigue property of injection molded jute/PP composites.
Mathematical Modelling of a Two Streams Coanda Effect Nozzle
Authors: Trancossi Michele , Maharshi Subhash , Angeli Diego
Published: April 2014

This paper analyses the ACHEON Coanda effect based propulsion nozzle for aircraft propulsion based on the dynamic equilibrium of two jet streams. It presents a large bibliographic analysis and the ACHEON concept and, in particular, the HOMER Nozzle, that is its main component. The Constructal optimization process that allows defining this architecture has presented. A preliminary mathematical model of a 2D case of the system has presented, focusing on the combined effect of the mixing effect of the two streams and the Coanda Effect Adhesion over a convex surface. A CFD preliminary validation has presented in uncompressible regime. The results have been evaluated in 2D cases.
Finite State Machine Assisted Automatic Tonnage Signal Clustering for Multiple-Operation Forging Processes
Authors: Lei Yong , Xie Haibo
Published: April 2014

Forging is an essential metal-working process in manufacturing. Forging tonnage signals, which are originally used to monitor the structural deformation of the forging machines for safety purpose, had been increasingly used to monitor the performance of the forging processes. Despite recent advances on forging process monitoring, little attention had been paid to expedite the preparation of the data labeling procedure for different fault classes of the forging tonnage signals. Currently, existing data are mostly classified and labeled by experts, which is extremely time consuming and error prone. In this paper, a new forging tonnage signal clustering method is proposed to label the multiple-operation forging tonnage signals automatically. Due to different workload setups of the forging machines, a Finite State Machine (FSM) modeling approach is developed to utilize the domain knowledge of the multiple-operation forging processes. An adaptive iterative learning scheme is deployed to optimize the clustering results based on minimum classification error of the tree-structure classifier based on FSM. Real-world forging tonnage signals are used in the case study to demonstrate the proposed method.
Effect of Severe Hot Forging and Rolling on Microstructure, Texture and Tensile Properties of Titanium Metastable Beta-Alloys
Authors: Ivasishin Orest , Markovsky Pavlo , Pozuelo Marta , Prikhodko Sergey V.
Published: April 2014

The influence of specific method of severe hot deformation, forging plus rolling, that ensures true deformation |ε| = 1.39 in single pass was studied on two metastable β-class titanium alloys VT22 (Ti-5.0Al-4.79Mo-4.70V-0.97Fe-0.71Cr) and TIMETAL-LCB (Ti-1.50Al-6.82Mo-4.47Fe), wt%. The results on microstructure, crystallographic texture and tensile properties are presented. It was found that this type of severe deformation forms elongated not-recrystallized β-microstructure with sharp axial (110)β texture, and fine α-precipitates inside the β-grains. In as-deformed condition both alloys are characterized by high tensile strength (above 1500 MPa) and very low ductility. Additional annealing at α + β temperatures does not change β-grain microstructure and crystallographic texture, but gives the structure a balance of strength and ductility. It looks very attractive for practical application of the alloys. Results are discussed in terms of specific mechanism of deformation accommodation.
Mechanical Characteristics of an Anodized Magnesium Alloy for Biodegradable Implants
Authors: White Leon , Neralla Sudheer , Kotoka Ruben , Jang Yongseok , Yun Yeoheung , Sankar Jagannathan
Published: April 2014

In recent years, magnesium (Mg) alloys have emerged as possible biodegradable implant materials; however the degradation rate of Mg occurs at a higher rate than tolerable for the human body. Plasma electrolytic oxidation (PEO) has been used in the past as a useful surface treatment technique to improve the anti-corrosion properties of Mg alloys by forming protective coatings. This present work focuses on the effect of electrolyte solution on the corrosion, microstructural, and nanomechanical behavior of PEO coatings for possible use in biodegradable implants. The experimental parameters applied during PEO process did influence the structure, thickness, and morphology of the coating. Microstructural characterization of the coating was carried out by X-ray diffraction (XRD), scanning electron microscopy (SEM) followed by image analysis and energy dispersive spectroscopy (EDX). Further, nanoindentation was employed to evaluate nanohardness and Young’s modulus of the PEO coating. The results show beneficial effects of the PEO coating to enhance the corrosion resistance of the uncoated AZ31 magnesium alloy. The XRD pattern shows that the components of the film vary based on electrolyte solution. The film composition does affect the nanomechanical behavior.
Electrical Discharge Machining of SiC and Gr Reinforced 6061-T6 Aluminum Alloy Hybrid Composite Fabricated by Friction Stir Processing
Authors: Kolli Murahari , Aruri Devaraj , Adepu Kumar
Published: April 2014

Aluminum based hybrid composites are advanced materials having the properties of high hardness, superior wear resistance, strength, high elevated temperature and low thermal expansion coefficient. These hybrid composites are widely used in industries like automobile and aerospace. In this present paper 6061-T6 Aluminum alloy reinforced with SiC and Gr particles, hybrid composites are fabricated by using Friction stir processing (FSP) technique. It prevents the further development of hybrid composites for machining by nonconventional methods like water jet and laser cutting process. Electrical discharge machining (EDM) is used for machining the complex shapes of the material. This paper presents an overview of EDM studies conducted on the Al-SiC/Gr hybrid composites using a copper electrode in EDM. The EDM experiment machining parameters such as the dielectric fluid, peak current, pulse on, pulse off times are changed to explore their effects on machining performance, material removal rate (MRR), Tool wear rate (TWR), and surface roughness (SR). It is observed that the MRR and SR of the Al-SiC/Gr hybrid composites increase with an increase in the current.
Experimental Investigation of Selective Laser Melting of Lunar Regolith for In-Situ Applications
Authors: Fateri Miranda , Gebhardt Andreas , Khosravi Maziar
Published: April 2014

Selective Laser Melting (SLM) is a powder based Additive manufacturing (AM) technology which builds an object layer wise using a laser beam to melt the powder on an elevated platform. Thus far numerous studies have investigated lunar manufacturing methods and construction but little is known about applicability of SLM of lunar regolith. As most lunar construction proposals require transportation of essential materials from Earth, using an in-situ manufacturing method with indigenous material would be considerably more economical. Fabrication of parts with SLM using various metals and ceramics has already been presented. As such, the feasibility of using lunar regolith mixture to create functional parts with SLM process is investigated. Variation of process parameters such as laser power, scan speed, and scan strategies is investigated and multiple 3D objects are successfully created and presented.
New Kinematic in Dressing of Grinding Wheels
Authors: Tawakoli T. , Daneshi A.
Published: April 2014

Grinding is the most important process in manufacturing of many precision components. The grinding wheel topography that is generated through dressing operation can directly influence the grinding forces and material removal mechanism. A new dressing concept is addressed in this investigation in order to reach the optimum chip formation condition. The innovative dressing profile roller, “T Dress”, creates a new structure on the wheel owing to which remarkable reduction in grinding forces occurs. The experiments prove about 40% reduction in grinding forces with no great difference in the ground surface roughness values when dressing with the T Dress. Dressing costs reduction owing to less diamond grits used on the roller body as well as about 25% lower dressing force are other advantages which were achieved with utilizing the T-Dress.
Model-Based Simulation and Optimization of Cutting Operations in Sheet Metal Working
Authors: Dhote G. M. , Kale A. V.
Published: April 2014

This paper presents method to calculate optimum punch entry inside the die block to avoid damage of the cutting edges. Experimentation is carried out on a hundred tonne capacity hydraulic press (AMINO, Japan make) with an inching facility. Piercing die with a hole size of 30 mm is used. Ten different materials are used with varying thicknesses. Punch entry was controlled by inching with 0.05 mm downward movement. Entry readings were noted at the point of fracture. Thickness and punch entry are correlated and a model is designed to compute percentage penetration with respect to thickness. Models are checked by simulation for various materials with varying thicknesses. These models we propose for all the industries to set the cutting dies at optimum entry to avoid damage of cutting edges.
Predictive Modeling of Surface Microstructure of Hardened Steel Subject to Drilling
Authors: Shen Ninggang , Ding Hongtao , Li Wei
Published: April 2014

Hole surface microstructures are very critical to the mechanical performance and fatigue life of metallic products from drilling processes. When steel material is drilled at a fully hardened condition, hole surface microstructures are often subject to transition because of the intense thermo-mechanical loading in the drilling process. A white layer can be formed on the surface of a drilled hole of carbon steels with high matrix hardness. The formation of the white layer mainly results from two reasons: thermally driven phase transformation and mechanical grain refinement due to severe plastic deformation on the machined surface.

In this study, a multi-step numerical analysis is conducted to investigate the potential mechanism of surface microstructure alterations in the drilling process of hardened steels. First, three-dimensional (3D) Finite Element (FE) simulations are performed using a relative coarse mesh with AdvantEdge for hard drilling of AISI 1060 steel to achieve the steady-state solution for thermal and deformation fields. Defining the initial condition of the cutting zone using the previous 3D simulation results, a multi-physics model is then implemented in two-dimensional (2D) coupled Eulerian-Lagrangian (CEL) finite element analysis in ABAQUS to model both phase transformation and grain refinement at a fine mesh to comprehend the surface microstructure alteration. The interaction among surface microstructures, drilling parameters and the hardness of the workpiece material are studied simultaneously. With the comparison to related experimental results, the capabilities of the multi-physics model to accurately predict critical surface microstructural attributes such as phase compositions, grain size, and microhardness during the drilling of carbon steel are demonstrated.
Friction Coefficients and Surface Properties for Laser Sintered Parts
Authors: Roppenecker Daniel B. , Grazek Rebecca , Coy Johannes A. , Irlinger Franz , Lueth Tim C.
Published: April 2014

Today different types of established rapid prototyping (RP) systems are available. In a Selective Laser Sintering (SLS)-process a CAD-model is designed and converted into a STL-file (Standard Tessellation Language). Next the body information is sliced into layers and transferred to the production system. By melting the powder-material using a laser beam, parts can be created layer by layer. Afterwards the parts are cleaned and several finishing treatments can be applied.

The primarily aim in using RP was to reduce the product development time and to create design models. Nowadays whole assemblies and complex parts can be produced altogether in one manufacturing step with RP-systems. To ensure a save part construction due to calculation formulas and basic material constants, predictable design calculations are necessary. Concerning SLS-materials like polyamide PA 2200 components, only specific mechanical values like the tensile and flexural modulus have been identified.

To fill this gap concerning tribological characteristics and to reach the next level of rapid manufacturing the key aspects of this article are the determination of the coefficient of friction μ0 of SLS-parts made of polyamide PA 2200 concerning several influence factors. An anisotropic material behavior, a decrease of the coefficient of friction μ0 with increasing contact pressure, larger contact areas and more intensive finishing treatment could be detected. Due to the knowledge of the identified material properties, now friction loaded components can be configured and used as functional machine parts.
Control Algorithm for Anti-Lock Braking System
Authors: Sahu Devesh , Sharma Rishi , Bharti Devesh , Srivastava Utkarsh Narain
Published: April 2014

Safer, controlled and efficient braking is the primary objective of Anti-lock Braking System wherein an efficient and robust braking system significantly enhances the vehicle performance during both straight line motion and cornering thus resulting in drastic reduction of stopping time and distance especially for a race car in long run. Hence clocking better lap times and a considerable reduction in wear of tires are an obvious outcome apart from the enhanced vehicle stability.

This work on Anti-lock Braking System (ABS) prediction and control algorithm deals with technical paradigm for estimation of vehicle velocity using wheel angular velocity from wheel rpm sensors as the sole input and methodology to control the braking torque on each wheel so as to prevent loss of traction. The proposed algorithm is modeled using advanced simulating tools involving theoretical estimation of braking torque on each wheel. This is supposed to reduce tire skid with controlled wheel slip estimated using the tire data and the car vehicle dynamics with formula student vehicle as the subject. The work and hence the control algorithm can potentially be extended into a better traction control strategy with acceleration and yaw inputs from accelerometers and yaw sensors.
MSIRP: Methodology for the Economic Viability of Semantic Interoperability Resolution Projects
Authors: Marcelino-Jesus Elsa , Sarraipa Joao , Antão Mário , Jardim-Goncalves Ricardo , Ilie-Zudor Elisabeth
Published: April 2014

Due to the current economy difficulties, companies need to dynamically establish business partnerships having at the same time a careful approach in doing investments. One of the main problems found in the establishment of such partnerships is related to the lack of semantic interoperability between the partners’ information systems. The integration and sharing of the knowledge representation elements of companies, has proportionated the appearance of semantic resolution projects. The paper presents a methodology to analyze the economic viability of companies in the application or development of such projects.
New Design Formula for Bolted Joints Under Tensile Loads
Authors: Sawa Toshiyuki , Omiya Yuya
Published: April 2014

In designing a bolted joint, it is important to estimate an increment in axial bolt force when an external tensile load is applied to an assembly. The ratio of the increment Ft in the axial bolt force to the external tensile load W is called the load factor φ(= Ft/w). The formula φ = Kt/(Kt+Kc) proposed by Thum has been applied for estimating the value of the load factor φ, where Kt is the spring constant of bolt-nut system and Kc is the compressive spring constant of clamped parts. It has been found that the value of the load factor varies with the position of load application to the assembly. Then, a method to compensate Thum’s formula was proposed. However, this compensation is made empirically and the theoretical background is not made clear. In this paper, the concept of the tensile spring constant Kpt for clamped parts is introduced newly when an external load is applied to the outer circumference of clamped parts (hollow cylinders) and a method for estimating the value of the load factor exactly is proposed by using Kpt. The value of Kpt is analyzed using an axisymmetric theory of elasticity. For verification of the proposed method, experiments were carried out to measure the load factor. A fairly good agreement is seen between the analytical and the experimental results of the values of the load factor while the values of the load factor obtained from Thum’s formula were so different with the experimental results. The reason why the difference in the values of the load factor is substantial between values and the values obtained from Thum’s formula is elucidated. It is found that the value of the load factor decreases as the outer diameter of the hollow cylinder increases and the as thickness of the clamped parts decreases. In addition, FEM calculations for the load factor are carried out. The FEM results are in a fairly good agreement with the theoretical results.
Fabrication of Three-Dimensional Tissue Scaffold Arrays Using Laser Foaming
Authors: Ock JinGyu , Philpott Bryan T. , Li Wei
Published: April 2014

The goal of our research is to develop a manufacturing method to create 3D cell-based microarrays for biomedical applications. Cells will be cultured in a large array of microscaled tissue engineering scaffolds that are fabricated on a polymer chip. In this paper, we present an experimental study and process modeling of a laser foaming process. Poly methyl methacrylate (PMMA) was used as the substrate material and CO2 was used as the blowing agent. Microstructures containing pores with varying topographical features at designed locations were created using laser. The effects of major process parameters such as gas concentration and laser intensity were investigated with respect to pore size and the size of foamed regions. The microstructure was evaluated with scanning electron microscopy (SEM). It was found that high intensity laser resulted in both a larger foamed region and an inverse cone-shaped well, which could be beneficial for cell culturing. A numerical model was developed to understand the laser foaming process and to predict the shape and size of the foamed region.
Innovative Geometric Redesign of Safety Footwear Components Using a Reverse Engineering Approach
Authors: Costa Sérgio L. , Silva Joel V. , Peixinho Nuno , Mendonça João P.
Published: April 2014

The normative behavior of innovative toe cap models for safety footwear with different thickness ranges and materials, including Advanced High Strength Steels (AHSS), was investigated by means of the quasi-static compression test. The main purpose of this work was to confirm the solution potential of a new geometric redesign model, from a reverse engineering approach, that maximizes the potential of energy absorption. The investigation was performed with two dissimilar and evolutionary geometric models, and several properties correlations such as: stiffness, thickness range and material properties. From a Finite Element Analysis and experimental test results of toe cap prototypes, it was found that the geometric factor had significant influence on the balance of the structural stiffness with thickness reduction. The study of the elastic deformation and the springback effect of different models, allows pointing an improved weight saving of a new toe cap component.
Table-Based Compensation for 5-Axis Machine Tools
Authors: Creamer Jennifer R. , Sammons Patrick M. , Bristow Douglas , Landers Robert G. , Freeman Philip , Easley Samuel
Published: April 2014

This paper presents a 5-axis machine tool compensation method that uses tool tip measurements recorded throughout the joint space to construct a set of compensation tables. The measurements can be taken using a laser tracker, permitting rapid measurement at most locations in the joint space. To compensate the machine tool, the measurements are used to identify a kinematic model, and then that model is used to construct an optimal set of compensation tables. The kinematic model is composed of the nominal, or ideal, kinematics with additional (unknown) six degree of freedom errors inserted between each of the joints. The error kinematics are identified using the measurement data and a maximum likelihood estimator. The identified model is then projected onto a joint-compensation space that maps to the compensation tables in the machine tool controller. Simulations of the approach are provided using measurement data from a Flow International 5-axis machine tool equipped with a Siemens 840D controller. The simulation results show a mean residual error of .076 mm, which is a 76.8% reduction from the uncalibrated machine tool.
Complex Sparse-Filled Mechanical Property Prediction Methods for Direct Digital Manufacturing
Authors: Kordonowy David N. , Giblin Sydney A.
Published: April 2014

This paper describes how direct digital manufacturing mechanical properties can be analytically estimated for structural use and the associated analytical and test methods used in the design and fabrication of airframes manufactured using additive manufacturing. Complex shape structures, which are now possible using additive manufacturing, and their associated mechanical properties can be predicted in order to allow operationally safe and highly predictive structures to be fabricated. Direct digital manufacturing allows for much greater flexibility and control over the design of airframes, leading to more structurally efficient and capable airframes. These advantages are revealed by application of direct digital manufacturing methods on a series of fixed wing subsonic transport concept wind tunnel scale models that are carried out as a part of the NASA N+3 program, which is paving the way for next generation aircraft that are highly fuel efficient, low-noise, and low-emission. Verification of these methods through test shows excellent correlation that provides reliability in complex sparse filled additive manufacturing design. The outcome of this is a knowledge base, which can then be applied to a system in operation. The combined potential of a flexible manufacturing system and proven predictive analysis tools shorten development time and expand the opportunities for mass customization. These combined benefits enable industry to fabricate affordable highly optimized custom products while concurrently reducing the cycle times required to field new products.
A Study on the Effect of Bird Hit Damage on the Dynamic Response of Aero-Engine Fan Blade
Authors: Channegowda Hithesh , Prakash Raghu V. , Kaliyaperumal Anandavel
Published: April 2014

Fan blades of an aero-engine assembly are the critical components that are subjected to Foreign Object Damage (FOD) such as bird impact. Bird impact resulting in deformation damage onto set of blades, which in turn alters the blade mass and stiffness distribution compared to undamaged blades. This paper presents the numerical evaluation of dynamic characteristics of bird impact damaged blades. The dynamic characteristics evaluated are the natural frequencies and mode shapes of post impact damaged set of blades and the results are compared with undamaged set of blades. The frequencies and mode shapes are evaluated for the damaged blades, with varying angles of bird impact and three blade rotational speeds. Study reveals that first bending and torsional frequencies of deformed blades are significantly affected compared to undamaged set of blades. Study emphasize the need to evaluate the natural frequencies deformed blades, that has direct bearing on High Cycle Fatigue (HCF) life of the blade, to ensure post damaged blades operate safely for certain time to reduce inflight accidents and safe landing.
Precision and Energy Usage for Additive Manufacturing
Authors: Clemon Lee , Sudradjat Anton , Jaquez Maribel , Krishna Aditya , Rammah Marwan , Dornfeld David
Published: April 2014

Market pressures on manufacturing enterprises incentivize minimum resource consumption while maintaining part quality. Facilities with advanced manufacturing tools often utilize rapid prototyping for production of complicated or specialty parts. Additive manufacturing offers an alternative to traditional production methods which are often time and resource expensive. This study aims to explore part quality and energy usage for additive manufacturing through a focused study of Fused Deposition Modeling and Photopolymer Jetting technologies. A control part is developed for maintaining test consistency across different machines. The control part design consists of various positive and negative features including width varied slots and walls, ramps, and curved features so that the manufacturing of different surfaces may be investigated. Several different machine models are tested to evaluate precision for a variety of applications. Part quality is quantified by measuring the surface roughness in two directions for the control test part printed on each machine. Qualitatively, part quality is assessed by positive and negative feature resolution. High quality machines resolve features closely to design specifications. Lower quality machines do not resolve some features. In addition to exploring the effects of advertised print precision, layup density is varied on two machines. Advertised print resolution does not well represent the achievable feature sizes found in this study. Energy usage is quantified by measuring electricity demands while printing the control part on each of the five different machines. Power consumption in additive manufacturing is found to follow a distinct pattern comprised of standby, warm up, printing and idle phases. Measurement and analysis suggest a relationship between the precision of these machines and their respective energy demand. Part quality is found to generally improve with increased initial and process resource investment. The energy and quality assessment methods developed in this study are applicable to a greater variety of additive manufacturing technologies and will assist designers as additive manufacturing becomes more production friendly. The presented data also provides designers and production planners insight for improvements in the process decision making.