bluuebunny/crossref_metadata_2025 huggingface dataset:
Research on Land Carbon Equilibrium of New City during Initial Stage of Urban Plan: A Case in Panjin New City, China
Authors: Guo Hai Bo , Zhang Ling Ling
Published: April 2013

The construction of a new city will change the use of land and break the original balance of carbon circulation. The carbon emissions will significantly increase duo to the human activity. The authors study the master plan of Panjin New City at the initial stage, calculate the carbon emissions and fixations on the basis of official statistics and relative formulas, and give the suggestions to adjust the project from the perspective of establishing carbon equilibrium. After calculation, the authors find:(1) Agricultural land, whose quantity of carbon fixations is 314.59 thousand tons per year, is the main carbon sink;(2) Urban land which mainly consists of residential land, industrial land and public facilities land is the main carbon source and release 813.12 thousand tons carbon per year; (3) The average per capita figure of carbon deficit is as much as 4.38 tons, which is 2.39 times as much as the standard level put forward by the United Nations. According to the data analyzing, the authors suggest that adjusting the proportion of the urban land, increasing the areas of green space and developing the ecological agriculture will be effective solutions to increase carbon surplus.
Effect of Sludge Retention Time in a Continuous-Flow Two-Sludge System
Authors: Luo Yu Jiao , Chen Yi Ming , Qiu Ling Feng
Published: April 2013

A continuous-flow two-sludge system was operated for efficient enhanced biological phosphorus removal. Phosphorus uptake took place solely under anoxic conditions with simultaneous denitrification in this system. Basic operating condition, namely sludge retention time was chosen as variable in order to assess its impact on the system performance. The experimental results indicated that the system could work stably and efficiently when the inflow was 100 L/h, the sludge retention time was 10 d, the internal bypass ratio was 30% and the reflux ratio was 30%.
Predication of River Water Quality Based on Gray Dynamic Model Group in Wenchuan Earthquake Disaster Area
Authors: Qian Feng , Lin Wei , Hu Bo , Liu Jing Jun , Xiong Ming Biao
Published: April 2013

“5.12 Wenchuan earthquake”triggered floods, landslide, collapse and secondary geological disaster, trigger a new soil and water loss, having the significant influence to the local river water quality.This article through the statistical analysis of minjiang river and jiangyou wenchuan, beichuan station 2006 ~ 2011 water conditions material, discussing the before and after the earthquake disaster areas of river water quality change characteristics. The results showed From ammonia nitrogen source analysis, urban sewage and industrial waste water, agricultural non-point source pollution and earthquake that triggered the new soil and water loss is the main pollution source. Based on the hydrological site total hardness concentration prediction, we can find wenchuan earthquake disaster area total hardness concentration significantly increase trend.
Study on the Protective Effect of Isolated Operation Mode on Micro-Grid
Authors: Zhang Si Qing , Li Xiao Fan , Hu Xiu Cheng , Ma Guo Hua
Published: April 2013

The protective effect of isolated operation Mode on Micro-grid was studied in this paper employing the method of contrast analysis. A model of Micro-grid system powered by wind and hydro was built using Matab/Simulink to simulate the two modes of isolation and connection under the circumstance of public power grid fault. Results show that the isolated operation mode of micro-grid is effective and necessary.
Study on Methods of Water Quality Analysis Based on Conventional Water Quality Monitoring Parameters
Authors: Feng Tian Heng , Huang Ping Jie , Hou Di Bo , Zhang Guang Xin
Published: April 2013

Water contamination events of urban water supply often show the characteristics of abruptness and variety, and the on-line water quality monitoring parameters usually are difficult to cover various contaminant parameters. With the help with routine detection and on-line water quality monitoring, it is possible to detect and judge whether a water quality event has happened or not and to identify its type indirectly, and obtain the relevant information of qualitative and quantitative analysis. These will be significant to the decision making by the concerning sectors and units. Taking the events of ammonium iron sulfate in the distribution system for example, the relationship of water between contamination concentration and conventional water quality monitoring parameters is investigated, and the quantitative method based on D-S evidence theory is given.
Water Quality Detection Using UV Spectra Based on the PCA Algorithm
Authors: Dai Lei Lei , Huang Ping Jie , Hou Di Bo , Zhang Guang Xin
Published: April 2013

Nowadays water pollution is a major problem facing our country, how to detect the water quality anomalies quickly is a major issue which needs to be solved urgently. In this paper, using PCA and cluster analysis methods, the similarities and differences of different water samples are analyzed. Meanwhile, two water samples belonging to the same river can be classified into different clusters due to different pollution degrees. It is promising that detecting the abnormal events based on the ultraviolet spectrum of water is possible. The research and results of this paper provide theoretical support and feasibility roadmap of the technology.
Research Progress of Typical Taste and Odor Compounds Produced by Chlorination in Drinking Water
Authors: Mao Min Min , Zhang Ke Jia , Zhang Tu Qiao , Yu Hong Liang
Published: April 2013

As disinfection by-products, the taste and odor (T&O) compounds were produced by chlorination at the end of water treatment. The existence of T&O compounds causes the pipe water with unpleasant odor and reducing water quality. Based on the latest research achievements at home and abroad, the characteristics and formation mechanisms of typical T&O compounds produced by chlorination are introduced. The new analytical method of electronic nose is also expounded. In addition, the common control technologies, such as pre-oxidation, activated carbon adsorption and bio-membrane, are reviewed. Since the precursors of T&O compounds shows small molecular, stable structure and low concentration, some coupling technologies including ozone-GAC, permanganate-PAC, and bio-membrane and GAC treatments, are employed effectively.Key words: chlorination; odor and taste compounds; disinfection by-products; precursor; electronic nose
Investigation of the Impact of Anti-Negative Pressure Facility on a Water Distribution System
Authors: Wang Huan Huan , Liu Shu Ming , Meng Fan Lin , Bai Lu
Published: April 2013

High level water tank is a commonly used facility to satisfy water demand for people living in high building, which is also the so-called secondary water supply system (SWSS) in China. Due to lack of maintenance, water quality problem has been frequently reported in the SWSS. In the last few decades, anti-negative pressure facility (ANPF) has emerged as a revolutionary approach for solving the pollution in the SWSS. ANPF makes good use of the municipal pipeline pressure, which is the improvement of traditional water supply. However, most of recent research activities mainly focus on the influence of part of water distribution system (WDS). In this paper, the software of EPANET has been applied in the SWSS calculation and simulation. Besides that, the SWSS with ANPF simulation method is proposed to evaluate the effect of other all nodes pressure in the WDS using hydraulic model. As the cases study, the paper analyzed two WDSs with ANPF. After simulation of the SWSS, the result of WDS, which is smaller, indicates that 6 out of the 9 nodes are affected with ANPF and that of WDS, which is larger, demonstrates that 37 out of the 41 nodes are affected and the affected nodes are focused on the confluent of pipes, especially around the ANPF.
Effect of Pocket Location on Combustion Process in Natural Gas-Fueled Rotary Engine
Authors: Wei Fan Bao , Feng Pan Jian , Xian Liu Yang , Rui Chen , Di Wu
Published: April 2013

In ordered to realize dynamic simulation of working process in the rotary engine, a spark-ignition rotary engine is chosen as the research object, the detailed calculated models have been established including combustion model and turbulence model. With numerical simulation, same important information in the cylinder is obtained, such as the velocity, temperature fields and flame propagation. Furthermore, the effect of pocket location on the flame propagation is analyzed. The results show that under the calculating condition, when the pocket is located at the rear of rotor, the rate of combustion and the peak pressure are better than that of other cases, and NO emissions increases accordingly. This study provides some theory guidance for the determination of best pocket location under different working conditions.
Field Test of Carbon Dioxide Gas Channeling Foam Plugging
Authors: Bao Yun Bo
Published: April 2013

Gas channeling is tending to happen in CO2 immiscible flooding process, and that would seriously influence gas injection development. In order to plugging gas channeling channel effectively, improve inspiration and production profile, and enhance swept volume and oil displacement efficiency of the gas injection, field trials of foam seal channeling are carried out. The tests showed that carbon dioxide foam can effectively plugging the gas channeling channel, expand the swept volume of carbon dioxide gas, reduce invalid circulation, and enhancing oil displacement efficiency. The anti-sealing channeling technology is cost-efficient, and it is suitable for Daqing peripheral low permeability oil field on gas injection development. It has good prospects, and it will provide a strong technical support on gas injection development of low permeability reservoir.
Numerical Simulation on the Stress Distribution of Thin Seam Containing Iron-Sulfide-Cores
Authors: Tan Yun Liang , Li Wei Min , Miao Su Jun , Wei Ping , Zhao Tong Bin , Li Quan
Published: April 2013

Fast Lagrangian Analysis of Continua in three Dimensions was adapted to establish numerical model of thin seam with Iron-sulfide-cores, based on the conditions of thin seam in Yanzhou Mining Area, and the influence of existing cores or not, cores in different positions, cores contents on mine pressure was studied. The results showed that, stress concentration and plastic zone is more easily to be formed in the coal around cores. When there are cores in coal, the bahaviors of abutment stress foreside the working face have no significant differences, the abutment stress curve is fluctuation and width or range of plastic zone little changed, but the boundary of plastic zone is fuzzy and radial. The boundary of plastic zone has some difference with the increasing of cores contents, but other macroscopic mine pressure behaviors has no significant differences. It is helpful to understand spalling mechanism of iron-sulfide-cores in thin seam.
Tahe Oilfield Ground Stress Analysis Model and its Application in the Barefoot Hole Wall Collapse
Authors: Yi Xian Zhong , Jiang Sheng Zong , Ji Yuan Qiang , Chang Wei
Published: April 2013

The T606 well in Tahe oilfield, deep core sample physical mechanical properties were tested to provide the experimental theoretical basis for casing failure analysis under the stress field. Afterwards, established the Tahe oilfield ground stress model based on the increasing fracturing data and related field ground stress models. The ground stress model is applied to calculate the critical level value of barefoot hole wall collapse in Tahe oilfield six and seven area. By regulating the production parameters and keeping borehole liquid level height above the critical level value, open hole collapse can be prevented.
Cuttings Characteristics and Mechanics Behavior in Horizontal Wells of Liaohe Oil Field
Authors: Yi Xian Zhong , Zhang Jun Feng , Jiang Sheng Zong
Published: April 2013

Cuttings transport of drilling and washing process in horizontal well is a typical two-phase (liquid-solid) or three-phase (gas-liquid-solid) flow phenomena. In this paper, it analyzes the flow characteristics of Huan 127-Lian H2 horizontal wellbore , then uses experimental method to study the behavior of the particle size distribution and the mechanics. This study provides an important way to master cuttings settling in fluid medium, it can explain how the cuttings bed is generated and cleared, and why the procession of cuttings of migration is stopped. In addition, measurement and analysis of drill cuttings is the basis erosion and abrasion analysis of BHA.
Factor Analysis of Vertical Hydraulic Fracture Geometry in Coal Bed
Authors: Wu Bai Lie , Cheng Yuan Fang , Li You Zhi , Xu Peng , Zhang Yu Ting
Published: April 2013

Hydraulic fracturing is one of the effective means to enhance coal bed methane production for vertical wells. This paper presents an approach that uses pseudo-3D fracture propagation model to study the influence of petrophysical properties, differential stress, treatment conditions, etc. on fracture geometry. It is shown that differential stress, pump rate is proportional to fracture length and width; elastic modulus, Poisson`s ratio, pump rate, etc. is proportional to fracture height. The finding is of great importance for acquiring ideal fracture geometry.
Application of Gas-Assisted Solvent Flotation Technique on Oil-Field Polymer-Bearing Produced Water
Authors: Li Ru Yin
Published: April 2013

The solvent flotation technique adopts organic solvent with low volatility as the second liquid phase, which could dissolve the components including emulsified crude oil, surfactant in the water. The modification of pH value, ion intensity, temperature, speed of air flow, and species of solvent could improve the efficiency of the flotation. The proposed method has been successfully applied to produced water treatment, the pharmaceutical industry sewage disposal and so on. It also has potential usage in sewage disposal of offshore oil field.
Research of Preparation of SO42-/TiO2-ZrO2 and its Application on Synthesis of Biodiesel from Waste Cooking Oil
Authors: Zhou Hou Bo , Cao Yang , Li Jin
Published: April 2013

SO42-/TiO2-ZrO2 was prepared by coprecipitation and dipping methods, and characterized by FT-IR, BET surface area measurement and NH3-TPD, and those results demonstrate the SO42- was loaded on the catalyst and the catalyst have enough surface area and pore size. The effect of methanol oil mole ratio, catalyst dosage, reaction temperature, reaction time on the conversion of waste cooking oil to biodiesel was investigated to find optimum reaction conditions. From the orthogonal experiments, the optimum reaction condition was shown as follows: methanol oil mole ratio is 25:1, catalyst dosage is 5% of oil, reaction temperature is 120°C, reaction time is 8h, the yield reached 96.68%.
Modelling Kinetics of Phase Transformation for the Indirect Hot Stamping Process
Authors: Hippchen Paul , Merklein Marion , Lipp Arnulf , Fleischer Michael , Grass Hannes , Philipp Craighero
Published: April 2013

To configure the indirect hot stamping process, a finite-element-based prediction of the parts geometry and mechanical properties is required. In case of indirect hot stamping, inhomogeneous cooling schedules cause different phase transformation points and products. The volume expansion caused by phase transformation of fcc into bcc leads to transformation induced stresses that are important for the calculation of overall stresses in press hardened components. To calculate theses stresses correctly, it is necessary to study the kinetics of phase transformation in consideration of the cooling path of an indirect hot stamping process. Dilatometer tests are employed to obtain the kinetics of phase transformation is determined in dilatometer tests. These results are used to identify the parameters for the phase transformation models implemented in the material model *MAT_244 [ that is implemented in the finite-element-code LS-DYNA [. In this context the material model parameters are identified by using evolutionary optimization strategies. Based on the identified parameters the predictive quality of the implemented phase transformation models will be studied in order to improve their prediction accuracy for the indirect hot stamping process.
Method to Emboss Holograms into the Surface of Sheet Metals
Authors: Behrens Bernd-Arno , Krimm Richard , Jocker Jan , Reithmeier Eduard , Roth Bernhard , Rahlves Maik
Published: April 2013

Holograms are industrially used as decorative design elements to increase the value of products. As they are hard to copy, holograms are also used for brand protection and product identification. The state-of-the-art is to emboss holograms in the surface of polymeric foils and to apply them to products by adhesive bonding. Examples are holograms on credit cards, banknotes or identification cards. In this paper, a new method to emboss holograms in the surface of sheet metals is presented. By this, parts made of sheet metal such as decorative interior parts of cars, battery housings or packaging of cosmetic products can be equipped with holograms during their production process. Hence, adhesive bonding and the required additional handling operations are not necessary. An embossing tool and the results of experimental hologram embossing are described. Aluminium Al99.9, aluminium-magnesium alloy AW-5505, copper and zinc-coated deep drawing steel DC05 were used as sheet metals to be embossed.
Furthermore, a new method and a device to produce master holograms are presented. Master holograms are required to produce embossing dies with the hologram on its surface (referred to as shim). The device is based on a laser light source and a spatial light modulator (SLM). With help of the SLM, simultaneous transfer of 1920 x 1080 pixels of a Computer Generated Holograms (CGH) topography to a plate coated with photoresist is possible. Compared to todays industrial mastering of holograms which is done pixel by pixel, the time required for the process is much shorter. In addition, investment costs are lower compared to currently used electron-beam-lithography devices.
Numerical Simulation of a Pyramid Steel Sheet Formed by Single Point Incremental Forming Using Solid-Shell Finite Elements
Authors: Duchêne Laurent , Guzmán Carlos Felipe , Behera Amar Kumar , Duflou Joost R. , Habraken Anne Marie
Published: April 2013

Single Point Incremental Forming (SPIF) is an interesting manufacturing process due to its dieless nature and its increased formability compared to conventional forming processes. Nevertheless, the process suffers from large geometric deviations when compared to the original CAD profile. One particular example arises when analyzing a truncated two-slope pyramid [. In this paper, a finite element simulation of this geometry is carried out using a newly implemented solid-shell element [, which is based on the Enhanced Assumed Strain (EAS) and the Assumed Natural Strain (ANS) techniques. The model predicts the shape of the pyramid very well, correctly representing the springback and the through thickness shear (TTS). Besides, the effects of the finite element mesh refinement, the EAS and ANS techniques on the numerical prediction are presented. It is shown that the EAS modes included in the model have a significant influence on the accuracy of the results.
Optimization of Superplastic Forming Processes for High Volume Production in Aeronautics
Authors: Nick Andreas , Zettler Joachim , Hirt Gerhard
Published: April 2013

Superplastic forming (SPF) is a well-known and widely used sheet metal forming process especially useful for the production of very complex and light thin sheet metal components. The superplastic behavior of a material is highly dependent on the temperature and occurs only at a narrow range of strain rates with an optimum value that is unique for each material. Within the aeronautic industry, this process is mainly used to form complex sheet metal parts made of the titanium alloy Ti6Al4V in heat affected areas and areas where corrosion resistance plays an important role. Even though the process times of SPF are often in the range of hours and therefore recurring costs are very high, the process is sometimes still the only choice when it comes to the forming of Ti6Al4V sheet metal parts for aeronautic or aerospace applications. To overcome the problem of long process times and high costs, in recent years, a lot of research did happen with the goal of temperature reduction during forming or forming at higher strain rates. Especially the change in the aeronautic industry towards high volume production is increasing the competition between suitable forming technologies and the SPF technology can only persist if both goals, reduction of process time and recurring costs are reachable. In this paper we will address those goals and show highly useful numerical procedures to make the SPF process ready for the next generation of aerospace manufacturing.
Blank Shape Optimization in Sheet Hydroforming Process
Authors: Del Prete Antonio , Papadia Gabriele , Primo Teresa , Schipa Silvia
Published: April 2013

Blank shape is one of the most important parameters of sheet metal stamping. In fact it can directly affect the forming quality of parts and it has to be taken in account in sheet hydroforming design. Reasonable blank shape not only can reduce materials and production cost but, also, it can improve the strain distribution of the material and product quality in the hydroforming process. However, it is not easy to find an optimal blank shape because of complexity of deformation behavior and presence of many process parameters like die radius, punch radius, punch speed, blank holder force and friction. In fact, they affect the result of the process i.e. tearing, wrinkling, springback and surface conditions such as earing. Even a slight variation in one of these parameters can result in defects. This paper reports numerical and experimental correlation for axis symmetrical hydroformed component using initial blank with different shape and size. Experimental tests have been carried out through the hydroforming cell tooling, designed by the authors thanks to a research project, characterized by a variable upper blankholder load of eight different hydraulic actuators. Two different initial blank shapes, square and circular, of same material and thickness have been used.
Profile Correction of a Stretch Formed Aluminium Alloy during Artificial Ageing
Authors: Volk Gregor , Leacock Alan G. , Brown Desmond
Published: April 2013

A method of springback reduction is presented which involves a combination of solution heat treatment, natural ageing, stretch forming and artificial ageing. A commercial aluminium alloy, 2219-O Hi-Form, is solution heat treated and subjected to two pre-form natural ageing periods of one and seven hours before the stretch forming process. Following the forming process an artificial ageing process combined with creep age forming techniques is used. Springback is assessed following the stretch forming and artificial ageing processes. This process is shown to provide a controlled means of correcting the springback following stretch forming.
Numerical Optimisation of a Shear Specimen Geometry According to ASTM
Authors: Merklein Marion , Johannes Maren , Biasutti M. , Lechner Michael
Published: April 2013

Complex material models used for the numerical representation of forming processes need in addition to tension and compression tests also shear tests to completely analyse the behaviour of the material under different loading conditions. There are two concepts of shear test one uses symmetrical specimens with two shear zones (according to Miyauchi) the other one specimens with a single shear zone. In both cases, a homogeneous distribution of the strain in the shear zone is essential for the validity of the shear test. Therefore, the length and width of the shear zone in a single shear specimen made from high strength steel according to the ASTM standard geometry were varied. Analysing the resulting strain distribution numerically an optimised sample geometry with a more uniform strain distribution than the ASTM standard was achieved. The numerical results were also validated with experimental shear tests.
FEM - Modeling of Bendability of Ultra-High Strength Steel
Authors: Arola Anna Maija , Mäntyjärvi Kari , Karjalainen Jussi A.
Published: April 2013

Ultra-high strength steels have been widely used in different industrial applications. It is necessary to understand the behavior of these materials in common forming processes such as air bending. It is known that the bendability of ultra-high strength steels is lower than other high-strength steels but what are yet to be discovered are the parameters that define the limits of bendability of these steels. The aim of this study was to investigate the factors affecting the bendability of ultra-high strength steel using optical strain measurements and FEM-modeling of the bending process. By using the true stress-strain relation measured by optical strain measuring system the bendability of ultra-high-strength steel was modeled fairly accurately. As a result, it was noted that the strain distribution at the bend of a steel possessing better uniform strain was more widely distributed and there were no highly localized strains. On the other hand as the failure occurred the strains were considerably smaller than the true failure strain of the material in uniaxial tension. As a conclusion it was stated that the ability to withstand the localization of deformation might describe the bendability of ultra-high-strength steel better than the values of the uniform or true failure strain in uniaxial tension test.
Experimental Study of the Formability of H240LA Steel Sheets under Stretch-Bending Conditions
Authors: Martínez-Palmeth L.H. , Martínez-Donaire Andrés J. , Vallellano Carpoforo , Centeno G. , García-Lomas F.J.
Published: April 2013

The present work discusses the effect of the punch radius on the formability of H240LA steel sheets of 1.2mm thickness. A series of hemispherical punch tests (Nakazima tests) and stretch-bending tests with cylindrical punches of different diameters have been carried out in order to characterize the influence of the strain gradient in the sheet failure. The limit strains have been obtained using a recently proposed time-dependent methodology, which is applicable not only in conventional Marciniak and Nakazima tests, but also in situations with a severe strain gradient through the sheet thickness. The results show that formability of H240LA steel sheets increases as the t0/R ratio decreases.
Effects of Surface Roughness on Frictional Behaviour of Solid Organic Lubricants for Sheet Metal Forming Processes
Authors: Sgarabotto Francesco , Ghiotti Andrea , Bruschi Stefania
Published: April 2013

In the last decades, national legislations have become even more restrictive about the application and the disposal of hazardous lubricants in sheet metal forming. As a result, metal forming industry, which traditionally has made large use of synthetic and oil-based lubricants to enhance the production rate and reducing the wear of tools, has been forced to study and develop new solutions to reduce the environmental impact of production processes. The introduction and the continuous improvement of environmental friendly lubrication systems has seen a continuous growth and attention, but today the usage of traditional hazardous lubricants is still significant, requiring expensive cleaning operations and harmful cleaning agents to remove them. The use of solid organic lubricants can reduce or eliminate this drawback, despite their performances may be significantly affected by specific process parameters and the presence of debris. In this paper the performances of a solid organic lubricant have been compared to traditional liquid lubricants applied to sheet metal forming applications. Different surface topographies have been reproduced and the effects in terms of frictional behaviour have been investigated.
Optimized Yield Curve Determination Using Bulge Test Combined with Optical Measurement and Material Thickness Compensation
Authors: Friebe Harald , Klein Markus , Heinle Ingo , Lipp Arnulf
Published: April 2013

Axisymmetric die and binder are typically used in the bulge test, where the test specimen is formed by increasing the level of oil pressure (Fig. 1). With this experimental setup a biaxial stress state is induced at the specimen dome, assuming that it is not influenced by friction. The increasing oil pressure in the region of the top of the dome is recorded and the deformation field measured during the forming process. The optical measurement system determines the coordinates, the deformations and the curvature on the outer surface. Based on the forthcoming ISO 16808 these results are directly used for the calculation of the flow curve. In order to determine the flow curve based on the bulge test, an analytical approach is needed for the computation of the stress state at the top of the dome.
Process Limits of Stretch and Shrink Flanging by Incremental Sheet Metal Forming
Authors: Voswinckel Holger , Bambach Markus , Hirt Gerhard
Published: April 2013

ncremental Sheet Forming (ISF) is a manufacturing technology for individualized and small batch production. Among the opportunities this technology provides there is the possibility of a short ramp up time and to cover the whole production chain of sheet metal parts by one machine setup. Since recent works showed that manufacturing of industrial parts is feasible, finishing operations such as flanging and trimming gain importance. This paper shows first works on the technological capabilities of using ISF for stretch and shrink flanging. Due to the localized forming zone the absence of surrounding clamping devices for ISF results in differing material flow behaviour. The influences of tool path characteristics, flange length as well as radii are analysed to set up a process window.
Friction Stir Spot Welding (FSSW) of Aluminum Sheets: Experimental and Simulative Analysis
Authors: D'Urso Gianluca , Longo Michela , Giardini Claudio
Published: April 2013

Friction Stir welding (FSW) is a solid state joining process developed by TWI (The Welding Institute) in 1991. This technology is suitable for joining different materials even considered difficult to be welded using more traditional techniques and it is appropriate to weld materials in different configurations (such as butt, lap, circumferential, T-joint etc). Recently, starting from the FSW approach, a new technology called Friction Stir Spot Welding (FSSW) was developed. In this case, instead of moving along the weld seam, the tool only indents two overlapped parts. In some applications, this technology can be considered as a valid alternative for single point joining processes like resistance spot welding (RSW) and riveting processes. This work deals with an experimental study of the FSSW process for the lap-joining of thin aluminum sheets. In particular, an experimental campaign was performed on AA6060 T6 aluminum sheets having a thickness equal to 2 mm. The FSSW process was applied on couples of overlapped sheets by varying the tool rotational speed, and by keeping fixed the other process parameters, such as axial feed rate, indentation depth, and dwell time. Welding forces distributions were recorded during the process. Preliminary tensile tests and metallurgical analyses were also performed to evaluate the quality of the joints as function of the chosen process parameters. A numerical model of the FSSW process was developed and implemented using the commercial FEM code Deform 3D. The model parameters were set according to the experimental evidence.
Tool Concepts and Materials for Incremental Sheet Metal Forming with Direct Resistance Heating
Authors: Meier Horst , Magnus Christian , Buff Bolko , Zhu Jun Hong
Published: April 2013

ncremental sheet metal forming with direct resistance heating is used for flexible sheet metal forming at elevated temperature, where electric current is conducted through the forming tool (s) into the forming zone. The electrical and mechanical contact combined with a high temperature of up to 600°C in steel forming results in complex tool requirements and a high wear of the tooltip. Starting with a description of a new process setup, both studies concerning existing and new tool concepts and materials will be presented in this paper. Therefore, the wear of different materials for tooltips and its dependence on lubrication has been investigated in forming experiments and will be thoroughly discussed.
Laser Forming of ERW Steel Square Tubes within Metallurgical Constraints
Authors: Sheikholeslami Ghazal , Griffiths Jonathan , Edwardson Stuart P. , Watkins Ken , Dearden Geoff
Published: April 2013

Laser forming (LF) is a non-contact method to shape metallic sheets and tubes by induced thermal stress without melting using a de-focused laser beam. Laser forming offers the industrial promise of controlled shaping of metallic and non-metallic components for prototyping, correction of design shape or distortion and precision adjustment applications. In order to fulfil this promise in a manufacturing environment the process must have a high degree of control, be repeatable and have a minimal impact on the material and mechanical properties of the part to be formed.
In order to demonstrate the capability of the LF process a study is presented in this paper on the 3D Laser Forming of ERW steel square tubes SHS EN10305-5 E220 +CR2 (1.5x25x25mm and 1.5x50x50mm 300mm long tube) using a 1.5kW CO2 laser and industrial 5 axis gantry. Strategies have been developed for out of plane bending with specific emphasis on process throughput balanced with minimising adverse localised changes to material properties that could lead to stress concentration features in a component in service. Presented in this paper is empirical 3D LF shape data verified by a scanning laser profiler, a metallurgical study, hardness testing and a FEM model developed in Comsol Multi-Physics. The results of these studies were employed to develop optimised scan strategies for the controlled laser forming of the ERW steel square tubes within strict metallurgical constraints.
Application of Kelvin Probe Force Microscopy (KFM) to Evidence Localized Corrosion of Over-Aged Aeronautical 2024 Aluminum Alloy
Authors: Radutoiu Nicoleta , Alexis Joël , Lacroix Loïc , Abrudeanu Marioara , Petit Jacques Alain
Published: April 2013

The 2xxx serie aluminum alloys are characterized by good mechanical performances and low density, however they are susceptible to different forms of localized corrosion: pitting corrosion, intergranular corrosion and stress corrosion cracking. The 2024-T351 aluminum alloy is used in the aircraft industry for numerous applications such as fuselage and door skin. Corrosion damage of the material is also very detrimental for the structural integrity of the aircraft. The presence of coarse intermetallic particles, with a heterogeneous size distribution was found to be responsible for the 2024 susceptibility to localized corrosion. These particles are generally the cause of initiation sites. Presence of micro-defects in the oxide film upon coarse intermetallic particles and the galvanic coupling with the matrix contribute to the development of pitting corrosion. The over-ageing treatment (T7) is supposed to stabilize the microstructure and the mechanical properties to improve the corrosion resistance. The 2024 alloy microstructure after the T7 heat treatment remains very complex. The 2024 alloy corrosion behavior was studied in the over-ageing state for three different temperatures (150, 175 and 190 °C). During the corrosion tests in chloride-containing environment, the behavior of coarse intermetallic particles was found to be different. Thus, the 2024 samples suffer a gradual attack upon S-Al2CuMg particles and finally Al (Cu,Mn,Fe,Si) particles. The corrosion damage was studied by Atomic Force Microscopy (AFM) and Kelvin probe Force Microscopy (KFM). This technique allows simultaneous topographical and electric potential mapping to be obtained. This latest potential was shown to be correlated to the corrosion potential of the 2024 alloy. This study focuses on the variation of the KFM potential of the coarse intermetallic particles and the matrix for the over-ageing conditions (T7). Observations using optical microscope and AFM were also performed to obtain the corrosion rate for each condition. The corrosion rate was correlated to the chemical composition variation of the particles obtained by scanning electron microscope observations and EDS analyses.
Mechanical Properties Investigation of Single-Walled Carbon Nanotube Using Finite Element Method
Authors: Tang Xing Ling , El Hami Abdelkhalak , El-Hami Khalil
Published: April 2013

This paper presents a three dimensional finite element model for armchair, zigzag and chiral single-walled carbon nanotubes (SWCNTs). The influences of diameter, chirality and length on the elastic moduli (Young’s modulus and shear modulus) of SWCNTs are investigated. The formulation presented is based on the assumption of viewing the construction of SWCNTs as a geometric frame-like structure. The interatomic interactions of bond length, bond angle, bond torsion and non-bonded interactions are equivalent to corresponding structure features straightforwardly. The models of SWCNTs are developed according to the atomistic structure network of nanotubes. The interatomic interactions of C- C atoms are simulated via appropriate straight spring and torsional spring elements. The computational results indicate that both diameter and chirality have a significant effect on the Young’s and shear moduli of SWCNTs, while the elastic moduli are not very sensitive to the variation of length. It is also shown that with a similar radius, armchair SWCNT has a slight higher value of Young’s modulus than zigzag and chiral SWCNTs. While zigzag SWCNT has a slight higher value of shear modulus than armchair and chiral SWCNTs.
Nanoscale Numerical and Reliability Method for Nano-Cantilever
Authors: El-Hami Khalil , El Hami Abdelkhalak
Published: April 2013

Most of nanostructures are desired in nanodevices in order to perform their characteristics. Tiny, strong and stable nanomaterials are needed to get functional nanosensor, nanoactuator and nanodevices. For those reasons, we introduce the single walled carbon nanotube (SWCNTS) as a high flexural and cylindrical nanocantilever to reduce the electrical and mechanical lost energy. Therefore, a bundle of SWCNTs in cylindrical geometry with a diameter of about 5 nm and 60 nm as long was designed in clamped-free cantilever feature. Due to the exceptional mechanical and geometrical characteristic of SWCNT, the first resonance frequency was calculated by analytical method to be of 150MHz. Further research, the SWCNT nanocantilever could be covered with a thin piezoelectric layer such as PZT, ZNO, AlN, PVDF...to realize nanactuators, nanosensors and nanodevices. The proposed methodology directly supports quality engineering aspects enabling to specify the manufacturing to achieve desired product reliability. Within this context, the robust design obtained is optimal over the range of variable conditions because it considers uncertainties during the optimization process. The large number of exact evaluations of problem, combined with the typically high dimensions of Finite Element models, makes reliability-based optimization procedures very costly, sometimes unfeasible. Those difficulties motivate the study reported in this paper, in which a strategy is proposed consisting in the use of reliability-based optimization strategy combined with measurement and sensitivity technique specially adapted to the structures of industrial interested. Keywords: single walled carbon nanotubes, nanocantilever vibration, clamped-clamped, clamped-free. Reliability, Finite Element Method.
A Study on Damping of Laminated Beams by Modal Analysis
Authors: Bensahal Djamel , Amrane Mohamed Nadir , Kharoubi Mounir
Published: April 2013

The paper presents an analysis of the damping of laminated beams with four different stacking sequences. The experimental investigation was conducted using tensile cyclic tests for different laminates studied. The impulse technique was chosen to perform modal analysis of the ease of implementation and quickness of the test. The numerical analysis is performed by the finite element method using beam element. The difference between strain energies for both cases damaged and undamaged are calculated by the finite element method. The structural damping of the different beams is evaluated from these energies. The decrease in frequency for different rates of loading shows the loss of stiffness for all materials studied.
Rheological Study of Composite Materials Based on Thermosetting Matrix and Fillers Mineral
Authors: Irekti Amar , Bezzazi B.
Published: April 2013

In the development of composites materials, the matrix acts as a binder of different reinforcements can distribute the stress, provide good resistance to chemical structure and the desired shape to the final product. But there are still some drawbacks that arise in the physicochemical and mechanical properties of thermosetting matrices. Our job is to synthesize composite materials with news formulations of thermosetting matrices (Granitex products) by the incorporation of 40% of local mineral fillers. The latter give the matrix properties which it does not have, first, to reduce the cost of composite materials, and secondly, to improve implementation by increasing the viscosity and reducing the withdrawal to its minimum value. Rheological testing of mixtures prepared is made on the cone-plate viscometer, or the sample undergoes a shear in the conical space between the plane and the cone. The geometry of the cone - package ensures constant velocity gradient throughout the volume. The rheograms obtained, represents the evolution of the shear stress as a function of shear rate of resin mixtures containing 35% of mineral filler (pozzolan). The mineral filler increases significantly in rheological parameters, whatever the nature of the mineral filler. Compared to the control without charges, an increase of 60% of the shear stress and that of plastic viscosity were recorded for the epoxy resin. The software Rheowine viscometer, enabled us to model and identified the rheological behavior of these mixed with resin. The results obtained in this modeling, confirmed that the resin mixtures have shear-thinning rheological behavior and their behavior follows the model of the Ostwald of Waele.
Thermomechanical Characterization of a Mortar Reinforced by Animal Fibers
Authors: Makhlouf Said , Khedache Souad , Djefel Dihia , Lefebvre Gilles
Published: April 2013

To meet the needs always more accurate and demanding in the construction industry, mechanical and thermal or acoustic features of building materials have known significant improvements over the last two decades. Researchers in materials science and civil engineering are constantly listening to the industry and continue to innovate in this field. The current trend is the search for new materials, called intelligent, where several properties as mechanical and physico-chemical are combined. In our case, the aim was to develop a new construction material reaching the construction standards, --- i.e. with acceptable mechanical properties --- but which is also able to perform other functions such as thermal insulation or sound insulation. To do this, we chose to strengthen a cement mortar with natural fibers obtained from poultry feather. A physical and chemical stability behavior is obtained thanks to a treatment performed before their incorporation into the composite matrix. The fibers are introduced in a mortar matrix as a substitute for mineral or synthetic fibers which are traditionally used for this purpose. The cylindrical and prismatic specimens were then prepared with the composite in order to determine the mechanical characteristics of this composite. Compression tests and three-point bending were carried out for this purpose. To determine the thermal conductivity of composites, several plates with different percentages of fiber, whose size is 300x300x10 mm3, was chosen in order to be adaptable to the experimental device, were fabricated.
A cost-benefit model comparing the California Milk Cell Test and Milk Electrical Resistance Test
Authors: Petzer Inge-Marie , Karzis Joanne , Meyer Isabel A. , Van der Schans Theodorus J.
Published: April 2013

The indirect effects of mastitis treatment are often overlooked in cost-benefit analyses, but it may be beneficial for the dairy industry to consider them. The cost of mastitis treatment may increase when the duration of intra-mammary infections are prolonged due to misdiagnosis of host-adapted mastitis. Laboratory diagnosis of mastitis can be costly and time consuming, therefore cow-side tests such as the California Milk Cell Test (CMCT) and Milk Electrical Resistance (MER) need to be utilised to their full potential. The aim of this study was to determine the relative benefit of using these two tests separately and in parallel. This was done using a partial-budget analysis and a cost-benefit model to estimate the benefits and costs of each respective test and the parallel combination thereof. Quarter milk samples (n= 1860) were taken from eight different dairy herds in South Africa. Milk samples were evaluated by means of the CMCT, hand-held MER meter and cyto-microbiological laboratory analysis. After determining the most appropriate cut-off points for the two cow-side tests, the sensitivity and specificity of the CMCT (Se= 1.00, Sp= 0.66), MER (Se= 0.92, Sp= 0.62) and the tests done in parallel (Se= 1.00, Sp= 0.87) were calculated. The input data that were used for partial-budget analysis and in the cost-benefit model were based on South African figures at the time of the study, and on literature. The total estimated financial benefit of correct diagnosis of host-adapted mastitis per cow for the CMCT, MER and the tests done in parallel was R898.73, R518.70 and R1064.67 respectively. This involved taking the expected benefit of a correct test result per cow, the expected cost of an error per cow and the cost of the test into account. The CMCT was shown to be 11%more beneficial than the MER test, whilst using the tests in parallel was shown to be the most beneficial method for evaluating the mastitis-control programme. Therefore, it is recommended that the combined tests should be used strategically in practice to monitor udder health and promote a pro-active udder health approach when dealing with host-adapted pathogens.