bluuebunny/crossref_metadata_2025 huggingface dataset:
Research on Information Dissemination Channelsand Monitoring of Sports Events
Authors: Yang Jun Wa
Published: May 2014

With the constant development of the social modernization the communications between people and people are more and more frequent; the progress of science and technology, an increase in number of communication mediums consumedly widen the information channels. In this paper, research on the information dissemination channels and monitoring of sport events is helpful for game organization to choose information, control the main factors in the process, and in order to acquire the best dissemination. This paper analyzes the main channels of match information. and makes some advice for the sports events ,after considering the features of each channel which the way receivers information. Meanwhile, we can establish a information dissemination monitoring system of sport event, which will provide a reference for game organization to control information effectively.
The Development of Badminton Auxiliary Training System Based on Kinect Motion Capture
Authors: He Zhen Dong , Hu Rui Min , Xu Jing Chao
Published: May 2014

With the growing number of professional sports training or national training began apply motion capture to sports training. Motion capture system is to assist training experts from multiple perspectives to observe trainer movements, and obtain the trainer of multiple motion parameters and physiological indexes, providing a reliable basis for scientific training. This paper develops auxiliary training system for badminton movement based on the analysis of the motion capture device, offering training guidance, rapidly improving the level of the trainer.
Research on the Network Security and Identity Authentication Technology
Authors: He Yi Hui
Published: May 2014

Network security and identity authentication is confirmed the true identity whether the user and the claimed identity is consistent or not, in order to prevent the illegal user access the system for resources by identity fraud. The one-time password authentication technology with high safety, convenient for using, easy for management and lower cost is applied widely and has bright prospection. The one-time password authentication technology support to add uncertain factors in the login process, so that the login authentication informations are not the same each time. It is useful to improve the security of the login process. In this paper, a new system which is based on the the one-time password authentication technology called biometric system is first introduced. Then the framework of multi-biometric system is presented, and several examples are also shown. The prospect about multi-biometric fusion is also given.
Disparity Map Acquisition Based on Matlab Calibration Toolbox and OpenCV Stereo Matching Algorithm
Authors: Gu Wei , Yin Jing , Yang Xiao Fang , Liu Pu
Published: May 2014

The key and difficult issue in the research of binocular vision-based 3D measurement is the accurate calibration of internal and external parameters of the camera and stereo matching. Matlab calibration is more efficient and accurate compared with manual or OpenCV calibration. In this paper, binocular camera is calibrated by Matlab calibration toolbox, and calibration parameters imported in OpenCV for follow-up image correction and stereo matching. By studying and comparing Block Matching (BM) and Graph Cut (GC) stereo matching algorithms, a disparity image of the object is obtained, thus laying foundation for follow-up 3D data information acquisition and reconstruction.
Parameter Identification and Comparative Analysis of Three Kinds of Rubber Bushing Model
Authors: Feng Bao Jin , Guan Xin , Guo Rui
Published: May 2014

In the process of vehicle design, the applications of large numbers of rubber bushing have great influence on adjusting and improving vehicle subjective performance and dynamic quality. In order to perform the characteristics of the rubber bushing more accurate, three models were selected as the object to study, such as Kelvin-Voigt model, Berg model and ASCL model proposed by the state key laboratory of automobile dynamic simulation. Static and dynamic forces were loaded to obtain experimental data. By analyzing the complex stiffness, the static and dynamic parameters of the three models are identified using the least square method. Finally, an analysis was carried out to compare the bearing characteristics of the three rubber bushing models.
Review of Task Scheduling Algorithm Research in Cloud Computing
Authors: Huang Mei Geng , Ou Zhi Qi
Published: May 2014

The cloud computing task scheduling field representative algorithms was introduced and analyzed : genetic algorithm, particle swarm optimization, ant colony algorithm. Parallelism and global search solution space is the characteristic of genetic algorithm, genetic iterations difficult to proceed when genetic individuals are very similar; Particle swarm optimization in the initial stage is fast, slow convergence speed in the later stage ; Ant colony algorithm optimization ability is good, slow convergence speed in its first stage; Finally, the summary and prospect the future research direction.
The Application of Digital Technology in the Recycling of Old Industrial Buildings
Authors: Li Peng Lin , Wu Li Jun , Zhou Bin
Published: May 2014

With the urban industrialization transforming to post-industrialization development, the negative effect brought about by the removal of old industrial buildings is the ignorance of the history of industrial development, thereby resulting in a waste of resources. With the development of computer technology, information technology and network technology, in the face of the old industrial areas losing produce production capabilities causes a lot of waste idle constructions, people can integrate information through digital means, renovate and reuse resources under complete information processing mechanism and systematically collect information. The application of intellectual and digital technology combined with each other provides a good foundation for the recycle of old industrial buildings resources, so that these representative old buildings resources can be used more widely and efficiently.
Analyses of the Relation Between Degree of Mixing and Regenerative Braking in Hybrid Electric Vehicles
Authors: Zhang Jing Ming , Liu Jin Long , Xue Ming Zhi
Published: May 2014

The introduction of driving motors brings in the function of regenerative braking for Hybrid Electric Vehicles (HEV). In order to study the further information of regenerative braking, the relation between the degree of mixing in HEV and the recovery rate of regenerative braking was analyzed. The study object was the front-wheel driving HEV with the wire-control composite regenerative braking control strategy. Conclusions were deduced through the theoretical derivation. The braking model was established on the platform in MATLAB/SIMULINK and it was simulated within a HEV. The results indicate that the recovery rate would increase if the degree of mixing rises.
Low-Temperature Sintering and Microwave Dielectric Properties of CaWO4-Mg2SiO4 Ceramics
Authors: Pan Chung Long , Chen Ping Cheng , Tan Tsu Chung , Lin Wei Cheng , Shen Chun Hsu , Lin Shin Hung
Published: May 2014

The effect of V2O5addition on the microstructures and the microwave dielectric properties of 0.9CaWO4-0.1Mg2SiO4(9CWMS) ceramics prepared by conventional solid-state routes have been investigated. The V2O5were selected as liquid phase sintering aids to lower the sintering temperature of 9CWMS ceramics. A small amount of V2O5(0.25~1 wt%) were used for sintering aid and led to high densification at 1050°C. The dielectric properties of 9CWMS ceramics with V2O5additions are strongly dependent on the densification, the microstructure. As the amount of V2O5additives increased from 0.25 to 1.0 wt%, the dielectric constantsεrdecreased following the trend with density. The quality valuesQdecreased with the increase of V2O5amount for all sintering temperatures. The 0.25 wt% V2O5-doped 0.9CaWO4-0.1Mg2SiO4ceramicssintered at 1080°C for 2 h had the optimum dielectric properties: εr= 5.7;Q×f= 73000 (at 14 GHz).
The Action Network of Clean Development Mechanism (CDM) in China
Authors: Liu Li Guang
Published: May 2014

Clean Development Mechanism (CDM) is a project-based climate mitigation scheme under the Kyoto Protocol. Since 2007, China has become the largest CDM credit supplier in the world. With the promotion of CDM projects, a flexible, consensus-seeking network that involves a variety of public and private actors has continuously been evolving. This paper provides a preliminary network analysis of how a wide range of public and private actors have been involved in the market-based CDM activities. It focuses on the development of action network and how the structural and interactive features of the network have impacted the policy outcomes. The paper concludes China has developed comprehensive action network for participating in the emission reduction activities, and the features of the network clearly reflect characteristics of Chinese political regime. Although China leads in CDM project activities, some regulatory measures may have the negative impacts on the full exertion of its potentials.
Micro Arc Oxidation of AZ91 Magnesium Alloy – Effect of Organic Compounds in the Electrolyte
Authors: Gozuacik Namik Kemal , Altay Mert , Baydogan Murat
Published: May 2014

AZ91 Mg alloy was micro arc oxidized under constant electrical parameters in silicate based and phosphate based electrolytes with and without addition of organic chemicals, namely Hexamethylenetetramine (HMTA), TRIS (hydroxymethyl) aminomethane (THAM) and Glycerol in two different concentrations. Following oxidation, samples were characterized by X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), coating thickness measurements, hardness measurements and electrochemical corrosion tests. Results showed that coating layers mainly consisted of MgO, Mg2SiO4 and MgF2 for silicate based electrolytes, and MgO for phosphate based electrolytes. Incorporation of organic chemicals into electrolyte composition did not change the type of the phases in the coating. However, when they are added in silicate based electrolytes, pore density and coating thickness are reduced and pore size is increased. On the other hand, there is no significant change in surface morphology when organic chemicals are added in phosphate based electrolyte. In the view point of corrosion resistance, organic chemicals did not enhance corrosion resistance of the samples oxidized in silicate based electrolytes, but exhibited some increment in corrosion resistance of the samples oxidized in phosphate based electrolytes.
Applied State Space Feedback Control of a Deep Drawing Process
Authors: Tommerup Søren , Endelt Benny
Published: May 2014

This paper presents results from application of discrete state spacebased feedback control of the blank holder force (BHF) magnitude and distribution in the drawing ofa rectangular workpiece. By means of monitoring the flange draw-in during the punch stroke, the controller makes continuousadjustments to the BHF magnitude and distribution by individuallycontrolling the pressure of a hydraulic fluid in a number of cavitiesembedded in the blank holder plate. The adjustments are conducted onlineduring the punch stroke to minimize the deviation of the achieved flange draw-in from a predetermined reference.
A Generalized Damage Model Accounting for Instability and Ductile Fracture for Sheet Metals
Authors: Lian Jun He , Jia Xiao Xu , Münstermann Sebastian , Bleck Wolfgang
Published: May 2014

With the requirement of vehicle performance and fuel economy, dual-phase (DP) steels as one of the advanced high stress steels (AHSS) are increasingly used in the automotive industry due to the excellent combination of the tensile strength and ductility. On a microscale the ductile fracture is governed by the void nucleation, growth and coalescence mechanism. In the dual-phase steels this damage mechanism exhibits a rather complex situation: voids are generated by the debonding of the hard phase from the matrix and the inner cracking of the hard phase besides by inclusions. On a macroscale fracture of these materials is observed in the automotive industry with the absence of strain localization or minimal post-necking deformation. Consequently the failure during the forming process is caused by a competitive or combined mechanism of internal damage evolution and metal instability. In this study, the target is to develop a simple and generalized model for metal forming processes accounting for instability, damage and ductile fracture. Theoretical predictions of metal instability by the Hill–Swift necking criterion and the modified maximum force criterion are considered. The damage model is developed by the combination of the prediction of metal instability and ductile fracture of sheet metals. The model is developed in 3D triaxial stress state and the accumulation of damage is stress state dependent. Furthermore, the influence of the hardening curve effected by damage on the forming limit curve is investigated.
Prediction of Post-Machining Distortion Due to Residual Stresses Using FEM and a Massive Removal Approach
Authors: Cerutti Xavier , Mocellin Katia
Published: May 2014

In aeronautics weight reduction of aircrafts has become one of the main objectives. This has led to the fact that a majority of the aeronautical parts made from aluminium are large monolithic parts (to avoid the use of assembling systems like rivets and screws). The manufacturing of these aeronautic parts, especially the structural parts, is usually performed by machining.
On large aluminium aeronautical parts, the main factor which can lead to non-compliance of a part is the re-equilibrium of the initial residual stresses inside the workpiece during the machining process.
In this paper, an example of multi-sided machining of a part made of AIRWARE® 2050 alloy is realised. Simulations of the machining of this part have been performed using a specific finite element tool which has been specially developed to predict the distortion due to the redistribution of these initial residual stresses during machining. Results numerically obtained are then compared with experimental results, showing a good agreement.
Cutting Force Model in Milling of Carbon Fiber Reinforced Plastic
Authors: Tamura Shoichi , Matsumura Takashi
Published: May 2014

The demand of carbon fiber reinforced plastics (CFRP) has been increased in aircraft and automobile industries. In milling of CFRP, the cutting parameters should be determined to finish the machining surfaces without delamination. The tool wear is also a critical issue to finish good surfaces. The paper presents a force model to study the milling process of CFRP. In order to investigate the anisotropy in milling of CFRP, the cutting tests were conducted for unidirectional CFRPs with changing the feed direction of the milling tool. The cutting force and the surface finish depend on the feed direction with respect to the fiber orientation. A force model based on the minimum cutting energy is applied to milling of CFRP. The orthogonal cutting data used in the force model is associated with the relative angle of the cutting edge rotation angle to the fiber orientation. The model was verified in comparison between the predicted and the measured cutting forces. The model also estimates the effect of the feed direction with respect to the fiber orientations on the cutting force in terms of anisotropy in the orthogonal cutting data.
Comparison between Wrought and EBM Ti6Al4V Machinability Characteristics
Authors: Bordin Alberto , Bruschi Stefania , Ghiotti Andrea , Bucciotti Francesco , Facchini Luca
Published: May 2014

Electron Beam Melting (EBM) is attracting large interest among the manufacturers of surgical implants as a near-net shape technology. Titanium alloy Ti6Al4V is widely used in the biomedical field thanks to its high biocompatibility, corrosion resistance and mechanical properties. The chemistry and microstructural features of EBM Ti6Al4V indicate lower machinability in comparison with wrought Ti6Al4V. Aim of the paper is to present a comparison between the machinability of wrought and EBM Ti6Al4V in semi-finishing external turning, by quantifying the effects of the cutting speed and the feed rate. Tool wear, surface integrity, chip morphology and microstructural analysis have been used to compare and assess the machinability of Ti6Al4V delivered in the two conditions.
Effects of the Flow Stress in Finite Element Simulation of Machining Inconel 718 Alloy
Authors: Jafarian Farshid , Ciaran Mikel Imaz , Arrazola Pedro José , Filice Luigino , Umbrello Domenico , Amirabadi H.
Published: May 2014

Inconel 718 superalloy is one of the difficult-to-machine materials which is employed widely in aerospace industries because of its superior properties such as heat-resistance, high melting temperature, and maintenance of strength and hardness at high temperatures. Material behavior of the Inconel 718 is an important challenge during finite element simulation of the machining process because of the mentioned properties. In this regard, various constants for Johnson–Cook’s constitutive equation have been reported in the literature. Owing to the fact that simulation of machining process is very sensitive to the material model, in this study the effect of different flow stresses were investigated on outputs of the orthogonal cutting process of Inconel 718 alloy. For each model, the predicted results of cutting forces, chip geometry and temperature were compared with experimental results of the previous work at the different feed rates. After comparing the results of the different models, the most suitable Johnson–Cook’s material model was indentified. Obtained results showed that the selected material model can be used reliably for machining simulation of Inconel 718 superalloy.
Thermo-Mechanical Behaviour of Spheroidal Graphite Iron
Authors: Le Mercier Kevin , Watremez Michel , Fouilland Laurence , Guérin Jean Dominique , Dubar Laurent
Published: May 2014

The main objective of this paper is to identify the thermo-mechanical behaviour of the spheroidal graphite (SG) iron EN-GJS-700. In the first instance, compression tests are carried out using Gleeble 3500 system enabling a precise control on testing temperature and strain rate. The effects of these testing parameters on the SG iron behaviour are studied. Through this, the occurrence of dynamic recrystallization phenomenon is highlighted. Specific rheological models based on metallurgy are introduced. Finally, shear tests on hat shaped specimens are performed to reach higher strain rates.
Wearing Evaluation in Nickel Super-Alloys Turning for the Development of a Predictive Model for CAM Optimization
Authors: del Prete Antonio , Franchi Rodolfo , Spagnolo Alessandro
Published: May 2014

Nickel super-alloys are characterized by: high temperatures resistance, high hardness and low thermal conductivity. For this reason they are widely used in critical operating conditions. However, due to their excellent properties, nickel super-alloys are hard to machine. Tool wear is a major problem in nickel super-alloy machining; the high temperature at the tool rake face is a principal wear factor. Flank wear is the most common type of tool wear; it offers predictable and stable tool life evaluation. In this work, the authors present a flank wear evaluation in Inconel 718 turning, in order to develop a predictive model for CAM optimization. An appropriate database has been developed thanks to an experimental activity (VB as a function of: the cutting time T, cutting speed S and feed rate F). The objective of the optimization procedure is to maximize the Material Removal Rate (MRR) under the constraint represented by the flank wear limit. The developed procedure operates directly on the part program code, using the original one as starting point for the application of the knowledge about the wear behaviour. After the optimization phase the given output is represented by a new part program code obtained in accordance with: the maximum MRR within the respect of the wear limit. s and tables etc.
An Object-Oriented Analysis of Complex Numerical Models
Authors: Macioł Piotr , Bureau Romain , Sommitsch Christof
Published: May 2014

Modelling the behaviour of metal alloys during their thermo-mechanical processing relies on the physical and mathematical description of numerous phenomena occurring in several space scales and evolving on different characteristic times. Although it is possible to develop complicated multi-scale models, it is often simpler to simulate each phenomenon separately in a single-scale model and link all the models together in a global structure responsible for their good interaction. Such a structure is relatively difficult to design. Both efficiency and flexibility must be well balanced, keeping in mind the character of scientific computing. In that context, the Agile Multiscale Modelling Methodology (AM3) has been developed in order to support the object-oriented designing of complex numerical models [.
In this paper, the application of the AM3 for designing a model of the metal alloy behaviour is presented. The basis and some consequences of the application of the Object-Oriented design of a sub-models structure are investigated. The object-oriented (OO) design of a 3 internal variables model of the dislocations evolution is presented and compared to the procedural one. The main advantages and disadvantages of the OO design of numerical models are pointed out.
Automatic Parameter Classification for Dimension Reduction as Basis for Robust Parameter Identification
Authors: Steffes-Lai Daniela
Published: May 2014

This paper presents a fully automatic parameter classification procedure in order to identify the most influencing parameters together with locally interesting parts of the component considered in a certain processing step. The results of this classification approach are used for a parameter space reduction in order to minimize the computational effort for subsequent analysis and optimization tasks based on forecast models. In particular, an outlook on the evaluation of radial basis function metamodels for a robust parameter identification is given. We demonstrate the classification procedure and its benefits by an industrially relevant deep drawing process of a pan with secondary design elements.
A New Process Chain for Joining Sheet Metal to Fibre Composite Sheets
Authors: Plettke Raoul , Schaub Adam , Gröschel Christian , Scheitler Chritian , Vetter Martina , Hentschel Oliver , Ranft Florian , Merklein Marion , Schmidt Michael , Drummer Dietmar
Published: May 2014

Mixed-Materials parts have great light-weight potential for the automotive application to reduce the carbon footprint. But the joining of fibre composite plastic sheets to metal sheets is in practical application limited to adhesive bonding or mechanical joining with additional fastener elements due to the large differences in physical properties. A new process chain based on plastic joining without fastener elements is proposed and first results on the mechanism and on the achievable strength of the new joints are shown. The process chain consists of three steps: First joining pins are added to the sheet metal by an additive manufacturing process. In a second step these pins are pierced through the fibre composite sheet with a local heating of the thermoplastic in an overlap setup. In the third and last step the joint is created by forming the pins with the upsetting process to create a shape lock. The shear strength of the joined specimens was tested in a tensile testing machine. The paper shows that even with a non-optimized initial setup joints can be realised and that the new process chain is a possible alternative to adhesive bonding.
Titanium Hot Stretch Forming: Experimental and Modeling Residual Stress Analysis
Authors: Astarita Antonello , Giorleo Luca , Scherillo Fabio , Squillace Antonino , Ceretti Elisabetta , Carrino Luigi
Published: May 2014

Titanium alloys, due to their high mechanical properties coupled with light weight and high corrosion resistance, are finding a widespread use in the aeronautic industry. The use of titanium in replacing the conventional alloys, such as aluminum alloys and steel, is reduced by both the high cost of the raw material (it costs anywhere from 3 to 10 times as much as steel or aluminium) and the machining costs (at least 10 times that to machine aluminium). For such a reason new technologies have been studied and developed. In particular many researchers are searching for technologies, such as the precision hot forming, that allows to obtain components with a low buy to fly ratio. Many of the airframe component structures are designed to fit against the inside radius of the fuselage curvature. By combining traditional stretch forming technology with hot titanium forming techniques, the HSF guarantees a saving in material and machining time, which are two serious cost issues for todays aircraft manufacturers. In addition, the process allows for consistent quality in a productively efficient manner, assuring the sustainable attainment of delivery and build schedules. In order to develop and improve the HSF process a modeling of the process itself was executed in order to study the stresses and strains undergone by the material among the deformation. The FEM model was validated through the residual stresses, and in particular the residual stresses provided by the model were compared with the ones experimentally measured using the hole drilling technique. Good agreement, in terms of stress range, was recorded both for the maximum and the minimum stress.
3D Numerical Simulation of Friction Stir Welding of Lap Joints Using an Arbitrary Lagrangian Eulerian Formulation
Authors: Gastebois Sabrina , Fourment Lionel
Published: May 2014

The numerical simulation of Friction Stir Welding (FSW) is carried out using an Arbitrary Lagrangian or Eulerian (ALE) formulation. Its computational cost is reduced by appealing to the parallel version recently developed within the Forge software. The accuracy of the numerical model is increased by enhancing the state variables remapping algorithm and by introducing a better suited time integration scheme based on the cylindrical coordinates. The pin and shoulder threads are modelled in order to account for this crucial phenomenon on material heating. The developed model provides quite satisfactory temperature fields for the FSW of a butt joint of 6061 aluminium, as compared to experimental results. It allows simulating welding defects such as tunnels holes or flashes. The study then focuses on numerical simulations and experimental measurements of a lap joint of a 7175 aluminium sheet on a 2024 aluminium sheet for an aeronautical application.
Thermal Study of Hot Stamping with Heated and Cooled Tooling to Obtain Tailored Properties
Authors: Blaise Alexandre , Bourouga Brahim , Dessain Christine
Published: May 2014

To produce parts with tailored properties, i.e. parts with high strength in some areas and high ductility on some other areas, one of the most popular method, called the tailored tempering process, is to heat up locally the tools. In the hot areas, the blank follows a different thermal path leading to different microstructure evolutions and thus different final mechanical properties.
In this paper, a tool is designed to have a side heated up to 500°C and a water cooled side. The hot side is heated up thanks to heated cartridges. A PID regulation is used to control the temperature of the hot side (from 200°C to 500°C) while the cold side is maintained at a low temperature using a thermostated water circulation. A uniform temperature on the working surface is successfully reached on both sides. Instrumentation by thermocouples is designed to be able to fully characterize the heat transfer: solving 2D heat conduction problems, the temperature fields in the tools and the thermal contact resistances at the blank/tool interfaces are estimated. Hardness measurements are also performed on the blank: the possibility to confer a distribution of mechanical properties is highlighted.
An Investigation of Phase Crystallinity in Laser Modified Yttria Stabilized Zirconia (YSZ) Thermal Barrier Coating
Authors: Reza Mohamed Suffian , Aqida Syarifah Nur , Mohd Toff Mohd Radzi
Published: May 2014

This paper presents laser surface modification process of plasma sprayed yttria stabilized zirconia (YSZ) thermal barrier coating (TBC) for enhanced hardness properties and low surface roughness. A 300W JK300HPS Nd: YAG laser was used to process YSZ TBC sample surface. The parameters selected for examination were laser power, pulse repetition frequency (PRF) and residence time. Micrographs of the TBC system were captured using EVO 15 Scanning Electron Microscope (SEM). Surface roughness was measured using 2-dimensional stylus profilometer. X-ray diffraction analysis (XRD) was conducted to measure phase crystallinity of the laser-modified coating surface. X-ray diffraction patterns were recorded in the 2θ range of 10 to 80° using Bruker D8 Advance system with 0.7Å wavelength from a copper source (~1.5Å). The laser modified surface exhibited higher crystallinity compared to the as-sprayed samples. The presence of tetragonal phase was detected in the as-sprayed and laser processed samples. The hardness properties of laser modified TBC increased 15% of the as-sprayed sample. These finding are significant to development of thermal barrier coating design optimization for enhanced surface properties of semi-solid forming die.
Numerical Investigation of the Hot Isothermal Process and Force Size-Effect of a Clutch-Half Forming
Authors: Petrov Pavel A. , Petrov Michael A. , Voronkov Viktor , Grishin Dmitriy
Published: May 2014

The paper deals with friction problems occur on the contact surface between the effect workpiece and tool and also size-effect during metal forming process. In the carried out numerical procedure the adaptation of the real isothermal conditions due to non-constant friction was investigated for original and resized experimental part. In scope of the paper two friction factors and one type of aluminium wrought alloy of the Al-Mg-Si-Cu system were used for numerical simulation, which were performed in QForm-2D/3D. Obtained results have shown that there is a functional dependency between deformation forces for original and resized forgings. It is quit independent from the friction factor and more depends on temperature.
Microstructures and Crack Formation in Hot Compression Test of Ultrahigh Carbon Steel
Authors: Kang Seong Hoon , Lim Hyung Cheol , Lee Ho Won
Published: May 2014

Experimental works were carried out to investigate microstructure and crack formation during compression tests of 1.9wt%Cultrahigh carbon steel according to temperature and strain rate. As-received ultrahigh carbon steel is composed of precipitated cementites and pearlite matrix. In addition, numerous voids were observed in the matrix of as-received material. The compression tests at 800 oC showed that the voids within the matrix are closed with increase of reduction ratio. On the other hand, when the reduction ratio increased numerous micro-cracks were newly formed in the bulky cementites and at the interfaces between hard cementite and soft matrix. It was also observed that because the volume fraction of cementite is reduced when temperature increased, volume fraction of newly formed micro-crack significantly decreased. Cast microstructures were observed after compression test at 1130 oC due to local melting. From experimental results and microstructure anlayses, it was concluded that the forging temperature should be controlled at the temperature of more than 900 oC and less than 1130 oC.
Injection Tests and Effect on Microstructure and Properties of Aluminium 7075 Direct Thermal Method Feedstock Billets
Authors: Ahmad Asnul Hadi , Naher Sumsun , Brabazon Dermot
Published: May 2014

The success of semi-solid metal forming is dependent on a globular solid grain formation within a liquid phase. This paper presents experimental works concerning semi-solid metal processing of aluminium 7075 feedstock billets which were produced by direct thermal method. The flowability of feedstock billets was evaluated by an injection test processing unit. The feedstock billets were heated to a temperature of 620 °C by using a box furnace before transferred into a forming die. The formed feedstock billet was removed from the forming die after it was cooled to ambient temperature. Several analyses were conducted on the formed feedstock billets including dimensional measurement and microstructure analysis. The results show that the feedstock billets which contained highest amount of free secondary phase were most successfully formed. Microstructure analysis results also revealed the formation of more globular and larger α–Al solid grains in the same feedstock billets. In this experimental work, the feedstock billets with higher secondary (liquid) phase gives a significant effect to formability. It can be concluded that in order to get successful formability of direct thermal method feedstock billets, the billets need to have higher secondary phase content. Thus, the selection of proper feedstock billets is important to determine the success of the SSM processing.
FEM Analysis for Tangible Component Production
Authors: Rosso Mario , Peter Ildiko
Published: May 2014

In high temperature metal forming techniques, analysis of the material flow and deformation as well as wear distribution during forging are very important, because they are directly correlated to the quality of the final component and to the productivity and die life. In this paper a commercially available Finite Element Method based simulator, namely Transvalor Forge 2008©, is used to numerically investigate on the effects of the various parameters on the mode of the failure of dies during hot forging. The exploration has the purpose to evaluate the possibility and related benefits of the advancement from a traditional hot forging process to a modern thixoforging one in the case study of steel-made steering pistons production. As a first step, the part related to the hot forging process is in detailed analyzed, in order to get an exhaustive description of the role of the different parameters. One step and two step solutions are proposed and discussed.
An Optimized Loading Path for Material Parameters Identification in Elastoplasticity
Authors: Ferreira Elisabete , Pinho-da-Cruz Joaquim , Andrade-Campos António
Published: May 2014

Presently, the need to characterize the constitutive parameters of materials has increased due to the manufacture of new materials and development of computational analysis software intending to reproduce the real behavior which depends on the quality of the models implemented and their material parameters. However, in order to identify all constitutive parameters of materials a large number of mechanical tests is required. Thus, only one mechanical test that could allow to characterize all the mechanical properties could be desired. Hence, the aim of this work is to propose a methodology that find the most informative loading path in the sense of display normal and shear strains as clear aspossible to warrantee that the solution is the most unique and distinguishable for the parameter identification process. To achieve this objective the proposed methodology uses Finite Element Analysis (FEA) and Singular Value Decomposition (SVD) coupled together with optimization strategies. Thismethodology is presented for elastoplasticity behavior.
The Effect of Product Size on the Pulling Force in Pultrusion
Authors: Baran Ismet , Carlone Pierpaolo , Hattel Jesper , Palazzo Gaetano S. , Akkerman Remko
Published: May 2014

In the present work, pultrusion of a composite rod is simulated for various part thicknesses using the finite element method. The pultrusion process set-up is taken from literature in which the temperature and the degree of cure evolutions inside the rod were measured. The predicted temperature and degree of cure profiles in the three dimensional (3D) thermo-chemical analysis are found to agree well with the measured data. The contact pressure between the part and the heating die is calculated using a mechanical contact formulation in the 2D mechanical process model for 9 different part thickness values. Using the contact pressure distribution along the die, the process induced pulling force is predicted. For the simulated cases, a non-linear relation is found between the total force and the product size.
On the Use of Explicit and Implicit Exponential Map Algorithms of Finite Strain Combined Hardening Plasticity in the Simulation of Draw Bending
Authors: Pietryga Michael P. , Vladimirov Ivaylo Nikolov , Reese Stefanie
Published: May 2014

The paper investigates the computational efficiency of explicit and implicit integrationschemes for hyperelastic-plastic combined hardening plasticity and examines the influence on thesimulated springback in sheet metal forming. The finite strain combined hardening model discussedhere is integrated by means of the exponential map algorithm in order to fulfil plastic incompressibility.The focus is on different possibilities of evaluating the exponential tensor functions of thematerial model. One option is to use the spectral decomposition to evaluate the exponential tensorfunctions in closed form. Alternatively, the latter functions can be determined by Taylor series expansion.We examine the potential of an explicit formulation of elastoplasticity with combined hardeningwith respect to accuracy and efficiency. The material model equations have been implemented as usermaterial subroutines UMAT and VUMAT for use in the commercial solvers ABAQUS/Standard andABAQUS/Explicit, respectively, where the finite element simulation of draw bending is simulatedboth in implicit and explicit manner.
Intended Dishing in Ring Rolling
Authors: Seitz Joachim , Schwich Gideon , Hirt Gerhard
Published: May 2014

Ring Rolling is a versatile metal-forming process to manufacture seamless rings of various cross-sectional geometries. Rings with a “dish shape” are used in different areas such as offshore, aeronautics or the energy sector. Current ways to produce dish shaped rings have the disadvantages of limited or inflexible geometries and either high material waste, additional costs for special tools or long process time. Instead, when manufacturing dish shaped rings on conventional radial-axial ring rolling mills, ring producers will be able to expand the range of their products easily. In a prior investigation, the general feasibility of an alternative to the current manufacturing processes was shown in experiments and in finite element method (FEM) simulations, avoiding major additional machining and material costs. Resulting from an analysis of the geometrical requirements and material flow mechanisms for dishing and ring climbing, a rolling strategy was derived, applying a large height reduction of the ring. A major problem of this rolling strategy is that whenever the contact between the ring and the main roll is lost in the process, the ring starts to oscillate around the mandrel and neither dishing nor ring climbing can be observed. In order to ensure a permanent contact between ring and main roll and in order to stabilize the ring in its inclined position in the rolling mill, additional stabilizing measures of the process will be developed and investigated. With the developed FE-model, a stabilizing measure by the use of pressure rolls and automatic guide roll movement for ring climbing was tested and appears promising for the application in a real experimental environment.
Buckling of Long Thin Plates under Residual Stresses with Application to Strip Rolling
Authors: Kpogan Kekeli , Potier-Ferry Michel
Published: May 2014

We present a simplified numerical method which can be used to predict efficiently the response of long thin plates under effects of residual stresses induced by production process such as rolling or continuous annealing. The principle consists in assuming harmonic buckling mode along the sheet length, and we consider Koiter-Budiansky post-buckling theory to compute the stress-deflection curve. In this way, only the width of the sheet has to be discretized by 1D finite elements. The size and shape of the flatness defects can be predicted efficiently and for a large number of cases. Various types of residual stresses and loadings can be accounted for. In particular, we will see the influence of the global traction on the buckling and post-buckling behavior. The numerical results are compared with experimental data and full numerical computations
A Computational Approach Based on Flow Front Shape Dynamic Behavior for the Process Characterization during Filling in Liquid Resin Infusion
Authors: Sanchez Fernando , Domenech Luis , Garcia Victor , Montes Nicolas , Falco Antonio , Cueto Elías , Chinesta Francisco
Published: May 2014

Resin Infusion (RI) process is one of the common techniques used in the industry for large composite parts production. This technique uses vacuum pressure to drive the resin into a laminate. Preform is laid dry into the mold and the vacuum is applied before the resin is introduced. Once a complete vacuum is achieved, resin is sucked into the laminate via placed tubing. Fig.1 shows a diagram of this process.An appropriate modeling of flow front’s shapes constrained by LRI process during filling can be based on the continuous deformation of the vent oriented flow pattern due to the driving pressure from the inlet. One of the main objectives is that the flow achieves the contour vent uniformly to avoid pressure drop and ensuring complete filling. In LRI, the flow front shape progression is mainly conditioned by the initial arrangement of the injection line allocation and the permeability of the preform that can evolve along the mold
Locking and Stability of 3D Woven Composite Reinforcements
Authors: Mathieu Sylvain , Boisse Philippe , Hamila Nahiene , Bouillon Florent
Published: May 2014

3D woven composite reinforcements preforming simulations are an unavoidable step of composite part processing. The present paper deals with thick composite fabric behavior modelling and issues arising during the numerical simulation of preforming. After the description of the independent deformation modes of initially orthotropic reinforcements, a physically motivated and invariant based hyperelastic strain energy density is introduced. This constitutive law is used to show the limitations of a classical finite element formulation in 3D fabric simulations. Tension locking is highlighted in bias extension tests and a reduced integration hexahedral finite element with specific physical hourglass stabilization is proposed. Instabilities due to the highly anisotropic behavior law, witnessed in bending dominated situations, are exposed and a stabilization procedure is initiated.
Material Modeling and Springback Analysis Considering Tension/Compression Asymmetry of Flow Stresses
Authors: Noma Nobuyasu , Kuwabara Toshihiko
Published: May 2014

In-plane tension/compression tests of a dual phase steel sheet with a tensile strength of 780 MPa were carried out using in-plane stress reversal testing machine. Remarkable tension/ compression asymmetry of flow stress (TCA) has been observed. Moreover, biaxial tensile tests using cruciform specimens were performed to measure contours of plastic work. The test material exhibited differential work hardening (DWH). In order to reproduce the TCA, an asymmetric quadratic yield function proposed by Verma et al. (2011) was used. The parameters of the yield function were changed as a function of reference plastic strain to reproduce the DWH. Furthermore, to assess the springback prediction accuracy of the developed model, a 3-point bending experiment and finite element analyses (FEA) were performed. It is concluded that the use of the material model that is capable of reproducing DWH and TCA is a must for a highly accurate FEA of springback.
Novel Intermediate Temperature Ceramic Composites, Materials and Processing for Siloxane Based Basalt Fiber Composites
Authors: Gadow Rainer , Weichand Patrick
Published: May 2014

SiC composites have been developed by various processing methods, i. e. reaction bonding, CVD/CVI and liquid phase impregnation. This class of composites is handicapped by the high cost of investment and processing, interface coatings and raw materials and therefore only attractive for applications in astronautics and military aviation. Polymer Matrix Composites (PMC) are widely used in lightweight applications. The manufacturing technologies are fully developed and raw materials are cheap. The major drawback and limiting factor of these reinforced polymers is the limited service temperatures. Novel composite materials, bridging the gap between PMC and CMC, are manufactured by the use of polysiloxanes as SiOC matrix precursor. Such competitive free formable composites are capable for service temperatures up to 800 °C even in oxidative atmosphere. In order to make the material attractive for series applications, cost effective manufacturing technologies like Resin Transfer Moulding (RTM), filament winding or warm pressing techniques are employed. Beside the improved thermal and chemical resistivity in comparison to reinforced polymers and light metals, a major benefit of SiOC composites is investigated in the field of friction materials. A promising alternative to carbon and synthetic ceramic fibers are mineral based Basalt fibers. These lightweight fibers show high thermochemical stability up to 700 °C, are relatively cheap and became recently available in industrial scale.
Influence of Friction on the Loads in a Roll Forming Simulation with Compliant Rolls
Authors: Mueller Christian , Gu Xun , Baeumer Lars , Groche Peter
Published: May 2014

Roll forming is an important economic forming process for manufacturing of profiles. For an optimal design of the process, it is important to determine the loads occurring during the forming process. Furthermore, the information of the load behavior enables an evaluation of the formability of the planned profiles with the chosen roll forming machine. An experimental determination of loads in roll forming processes requires a complex measurement setup in combination with a high amount of measurement devices. Hence, the analysis of roll loads by means of finite element simulation is of special interest. The use of roll forming simulations for the determination of geometrical outputs is state of the art. However, due to simplifications, a realistic and reliable output of roll loads in roll forming is impossible. Therefore, the compliance behavior under load and the frictional behavior have to be incorporated in the simulation model. The friction behavior in roll forming processes is presented to be very insignificant in literature. The value of the friction coefficients vary in a broad range. Due to lack of knowledge in the compliance behavior of the used stands, simulation models with rigid rolls are still state of the art. This paper will show the reproduction of realistic roll loads, e.g. torques and forces, in a roll forming simulation. Therefore, the friction coefficients of each roll-sheet metal contact will be gained experimentally and implemented in the numerical model. Furthermore, a characteristic compliance of the roll forming stands will be analyzed and also considered in the simulation. Finally, the influence of changing parameters, e.g. raise of the friction coefficients, on the roll loads will be investigated. To verify the simulation the numerical results will be compared to data gained by experiments.