bluuebunny/crossref_metadata_2025 huggingface dataset:
Study on the Application of SMES to Improve Power Quality
Authors: Zhou Xue Song , Shi Xue Qi , Ma You Jie
Published: September 2013

With the development of modern technology, high quality power supply becomes more desirable in everyday life. Among problems related with the power quality, the most urgent is the voltage dip; with the application of power electronics devices, the power system is polluted by harmonics. SMES (Superconducting Magnet Energy Storage) system can not only compensate the voltage dip, but also provide a load-fluctuation compensation and active power filter. In the paper the main structure of SMES system is introduced; the necessity to use SMES are demonstrated by analyzing the problem of power quality. The analysis shows that SMES system is effective in improving the power quality.
Complex Analysis of Electrical Resistivity Dynamics of Co82Fe4Cr3Si8B3 Amorphous Alloy under Heat Treatment
Authors: Kotvitckii Aleksandr , Kraynova Galina , Frolov Anatoly , Ivanov Vitaly
Published: September 2013

In this paper the detailed analysis of thermal behavior of electrical resistivity of Co82Fe4Cr3Si8B3 amorphous alloy is made. It has been shown that within temperature range 230С <T< 5600С the structure of the alloy keeps its amorphous character and only a slight changes occurred. A high temperature (above room temperature) resistivity minimum was found at 160°C. This feature was related with Curie temperature of the alloy. It has been shown that change of electrical resistivity behavior at 350°C can be explained by reaching the Debye temperature of the alloy.
Synthesis and Characterization of Stearoyl Modified Poly (Glycerol Adipate) Containing ATRP Initiator on its Backbone
Authors: Naolou Toufik , Jbeily Mark , Scholtysek Peggy , Kressler Jörg
Published: September 2013

Poly (glycerol adipate) is enzymatically prepared by reacting glycerol with divinyl adipate in the presence of a lipase as catalyst fromCandida Antarcticatype B (CAL-B). The reaction yields linear polyesters with free pendent hydroxyl groups. Poly (glycerol adipate) is hydrophobically modified by incomplete acylation of some of the pendent hydroxyl groups using stearoyl chloride. The resulting polymer is further functionalized with α-bromoisobutyryl groups. The final polymer is purified and well characterized to calculate the ratio of substitution in both cases. Furthermore, nanoparticles in water are prepared from the functionalized polymer using the interfacial precipitation method. Dynamic light scattering measurements depict nanoparticles with relatively narrow size distributions and with an average hydrodynamic radius of 70 nm. Additionally, transmission electron microscopy images reveal well dispersed spherical nanoparticles with nanophase separation. Finally, the interactions between the graft copolymers and lipid monolayers of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) are investigated on a Langmuir trough equipped with a fluorescence microscope.
Aromatic and Epoxidised Oil Curing and Rebound Resilience Characteristic and their Humidity Effect of Hardness on NR Vulcanizates
Authors: Rahmah Mohamed , Norazira Wan Zain , Nur Ashyikin Shafie , Norizan Mohd Nurazzi
Published: September 2013

Recently, aromatic oil (AO) is one of the substances that is typically used as a processing aid especially for high filler loadings in formulating rubber compound. Aromatic oil has disadvantages in that, it is hazardous to environment, toxic and has been labeled as carcinogenic. In this research, an epoxidised oil (EO) and aromatic oil were used to investigate the effect incorporation of oil onto the SBR/NR natural rubber vulcanizates (NR). From the result obtained, EO showed shorter cure time and scorch time as the oil loading were increased up to 20 pphr of EO. Physical properties such as hardness and rebound resilience of NR/EO vulcanisate were also investigated upon exposure to different humidity level in humidity chamber. At room temperature, the hardness of EO loading onto the SBR/NR vulcanisate is lower than AO loadings. Hardness was slightly decreased with increasing rate of humidity. There is great difference in hardness and rebound resilience values between AO and EO. Both hardness and rebound resilience were not affected by humidity. This implies the existence of good filler interaction with EO and rubber which do not impart changes in the hardness and resilience properties of rubber compound. Epoxidised oil has great promising potential to replace the carcinogenic aromatic oil as it has good overall performance and renewable in nature .
Effect of Epoxidized Palm Oil (EPO) on Tensile Properties and Density of Rubber Compounding
Authors: Anis Nazurah Mohd Nasir , Romli Ahmad Zafir , Wahab M.A. , Abidin Mohd Hanafiah
Published: September 2013

Epoxidized palm oil (EPO) can act as processing oil has the potential of non toxic, degradable, renewable resource and as the alternative safe process oils in rubber compounding. Epoxidized palm oil is used as some of additives in rubber compounding to provide function of softener or stabiliser thus, improve properties of rubber compounding performance. Rubber that is used in this study is styrene butadiene rubber (SBR); a synthetic rubber copolymer consisting of styrene and butadiene. SBR also has good abrasion resistance and good aging stability when protected by additives. Compared to natural rubber, SBR has better processability, heat aging and abrasion resistance but inferior elongation, hot tear strength, hysteresis, resilience and tensile strength. This study is focusing on the effect of EPO without the addition of carbon black into the compound via tensile and density test. This is very important as to study the physical and mechanical interaction between SBR and EPO without the influence of other fillers. Different loading of oil were used at 25 pphr, 30 pphr. 35 pphr, 40 pphr and 45 pphr in the compounding process as processing aid. EPO35 which contain 35 pphr of EPO shows the highest value of tensile strength which is 2.2 MPa. The vulcanizate that contain 30 pphr of EPO shows the highest value for Youngs modulus which is 0.22 MPa while the elongation at break increased as the oil loading increased. The highest value for density is 0.979 g/cm3for the vulcanizate contain 25 pphr of EPO. The results indicates that EPO is potential to replace other processing oils as renewable resource and safe to human.
Influence of Thermal Treatment on the Molecular Weights of Polyhydroxyalkanoate Containing 3-Hydroxyhexanoate
Authors: Salim Yoga Sugama , Chan Chin Han , Sudesh Kumar , Gan Seng Neon
Published: September 2013

With blooming interests in the research of biodegradable polyesters produced from microorganisms as well as polymer processing and technology, this study is intended to reveal the influence of thermal treatment on the molecular weight of poly (3-hydroxybutyrate-co-3 mol% 3-hydroxyhexanoate)/P(3HB-co-3 mol% 3HHx), a copolymer of polyhydroxyalkanoates (PHA). P(3HB-co-3 mol% 3HHx) was thermally treated using Differential Scanning Calorimeter and analyzed using Gel Permeation Chromatography and Attenuated Total Reflectance-Fourier transform infrared (ATR-FTIR) spectrometer. Results from gel permeation chromatography suggest a major reduction of molecular weight up to 50 % when P(3HB-co-3 mol% 3HHx) is exposed to 180 °C for 30 mins. The half-time degradation of P(3HB-co-3 mol% 3HHx) treated at 170 °C and 180 °C is 14.1 and 9.9 mins, respectively. FTIR spectroscopy shows an increase absorbance intensity of P(3HB-co-3 mol% 3HHx) after thermal treatment, indicating a formation of more alkenyl and carboxylic end-group in polymer chains due to random chain scissions.
Antistatic Tire Tread Made from Epoxidized Natural Rubber Based Compound
Authors: Yong Kok Chong , Che Aziz Ahmad Kifli
Published: September 2013

A vulcanized epoxidized natural rubber (ENR) based electrically conductive compound was successfully prepared by using the combination of internal mechanical mixing and open milling devices. This compound was developed based on a formula with at least 73.0 wt % of petro-chemical free ingredients. The vulcanizate of this compound showed good physical properties, high electrical conductivities and also complied with Malaysia Standard 1097 [. As a result, this newly formulated compound can be targeted for making antistatic tire tread of commercial vehicles.
Thermal and Physical Properties; and Surface Morphology of Waterborne Maleinized Epoxidized Soybean Oil Films for Coatings Application
Authors: Mohd Ahmad Faiza , Firdaus Yhaya , Nur Safwah Basri , Kamarun Dzaraini , Mona Rita Othman , Azlan Zakaria , Raden Siti Amirah Hambali
Published: September 2013

In this study, waterborne maleinized epoxidized soybean oil (WMESO) films were prepared and characterized in order to investigate their thermal properties, mechanical properties and surface morphology. A series of coating films were cured onto glass substrate. Differential Scanning Calorimetry (DSC) analysis showed that the coating films have glass transition temperature (Tg) ranging between 36-38 °C. Thermogravimetric analysis (TGA) revealed that waterborne films couls stand very high temperature up to 600 °C. W-2.0 was the best sample in terms of hardness. Film adhesion test showed that the adhesion between film and substrate was good. Higher initial water content gave films with better physical properties but poorer adhesion to substrate. Scanning Electron Microscopy (SEM) was used to visualize the surface morphology of film as well as the formation of resin. It was observed that, the particles were well dispersed and were crosslinked to each other.
Study on Cure Characteristics and Mechanical Behaviours of Kenaf Fibre Reinforced Natural Rubber Composites
Authors: Nurul Aizan Mohd Zaini , Zainathul Akhmar Salim Abdul Salim , Mohd Muhiddin Ahmad , Nor Hazwani Zainudin , Siti Sarah Jamil
Published: September 2013

In recent years, natural fibres appear to be as an outstanding material to substitute the conventional reinforcement materials in polymer composites. Kenaf fibre reinforced natural rubber (KFNR) composite was prepared by incorporating of different loadings of kenaf fibre using two roll mill machines. The compound was vulcanised at 150°C according to their respective cure time. The intention of this study is to investigate the influence of kenaf fibre on cure characteristics and mechanical bahaviour of (KFNR) composites.The result showed that the higher fibre content in composites led to shorter optimum cure time, t90. It was also observed that the tensile strength and elongation at break gradually decreased with an increment in fibre loadings. However, the trend was not similar for the hardness where the hardness value was increased by the increment of fibre loadings. The study has exhibited that the optimum fibre loading for the best performance of the composite achieved was 10 phr. The Scanning Electron Microscopy micrograph clarified that fibre dispersion and adhesion were weak thus resulting low in tensile strength and elongation at break.
Synthesis and Characterization of UV-Curable Cross-Linked Carbazole Substituted Poly(Dimethylsiloxane) for Optoelectronic Encapsulant
Authors: Norhuda Hidayah Nordin , Nadras Othman , Zulkifli Ahmad
Published: September 2013

This paper report the synthesis of a crosslink network of Carbazole substituted Poly (dimethylsiloxane). Vinyl Carbazole and Vinyl Trimethoxysilane were introduced into polydimethylsiloxane chain backbone through hydrosilylation reaction. 4-hydroxybutyl acrylate was then grafted into vinyl trimethoxysilane by condensation followed by UV curing to afford an elastomeric crosslink network. FTIR and 1H NMR spectroscopy were used to confirm the structure of the product as well as monitoring the progress of the reactions. The visual observation shows the changing appearance of the samples with increasing curing time and distance from UV exposure. The materials displayed refractive index between 1.407 1.452 which is within an acceptable range of application as electronic encapsulant. The crosslink network improved material hardness compared to that without. These properties were examined and thoroughly discussed within the scope of Lorentz-Lorenz model.
Processing Optimization of Optical Lens in the Injection Molding
Authors: Lin Chao Ming , Wang Chih Kun
Published: September 2013

The processing conditions during the manufacturing have critical effects on the optical performances of the molded lenses including the refractive index, isochromatic fringe order, and the fringed pattern. The objective of this work is to investigate numerically some effects of the molding conditions on the residual stresses of injection molded lenses, and then to optimal the processing parameters for reducing the residual stresses using the Taguchi method. The results show the optimal method is able to improve the residual stress and to produce a good fringed pattern.
Experimental Study on Geometries Energy Absorption of Fiber Metal Laminated Mild Steel under Axial Compression
Authors: Sahak Muhammad Izani , Mohamad Ahmad Kamely , Ariffin Abdullah Atiq
Published: September 2013

Crashworthiness is the ability of a structure to protect its occupants during an impact. Depending on the nature of the impact and the vehicle involved, different criteria are used to determine the crashworthiness of the structure. The combination of metal and composite layers is known to displays plastics deformation and failure mode composite layered. The capable of structures to absorb large amount of energy are great interest in an effort to reduce the impact of collision. In this experimental study, an investigation will be carried out on geometries behavior of fiber metal laminated mild steel under axial compression. For structures subjected to compression, energy absorption is highly desirable and will depend on its physical shape. The efficiency is measured in term of the absorption performance that is higher in hybrid composites than in metallic and composite structures. Much of the working assessing the energy absorbing capability of composite materials and structures under compressive loading has been to a greater extent restricted to axis metric tubes. Therefore, it will contribute knowledge on how to design hybrid composite material tubes to develop a stable or controlled compression response under sustained axial loading.
Research on Task Sequencing of Mixed Model Assembly Workshop Based on Improved AHP
Authors: Wang Zhe , Song Yan Fang , Cui Geng Yan
Published: September 2013

The influence factors of task sequencing in mixed model assembly workshop is analyzed, and the production reasonable degree comprehensive evaluation index system is established with research of the evaluation index quantifying method\. The objective and subjective influence factors of task sequencing are analyzed, and the shortage of using AHP to sequence tasks alone has been pointed out. The improvement of AHP on the basis of entropy weight method has been researched, and task sequencing method of mixed model assembly workshop based on improved AHP has been proposed. The method has been verified in aero-engine assembly workshop, and the results show that it is feasible.
A Copper Oxide Ore Treatment by Flotation
Authors: Ge Bao Liang , Fu Yan Xiong , Li Qing
Published: September 2013

The ore containing 0.77%copper, the main metal minerals in the ore are hemesite, pyrite bornite, covellite, malachite, the main gangue minerals in the ore are quartzite, dolomite, plagioclase, Chlorite, calcite. And the copper oxidation ratio of the ore is 45.5%, According several flotation tests, finally found that the optimum reagents dosage are: butyl xanthate 90g/t as collector, pine oil 35g/t as foaming, sodium sulphide1000g/t, lime3000g/t, and the flow-sheet is one stage of roughing, three stage of cleaning and two stage of scavenging operationg in the close circuit under the grinding fineness is 85% -0.074mm.Satisfactory results had been obtained as the grade of is 18.06% with recovery 80.01%.
The Study on the Mineral Phase Transformations and Thermodynamics of Laterite Ores Calcination
Authors: Xu Yu Ling , Chen Song , Gui Shu Qiang , Bian Yu Yang , Ding Wei Zhong , Tan Ding Sheng
Published: September 2013

In this paper, mineralogical phase transformations of Indonesia nickel laterite ores are studied during calcinations, the thermodynamics of process are also investigated. Different factors that affect the reduction of the laterite ores are tested and analyzed by Differential Scanning Calorimeter (DSC), X-ray Diffraction (XRD), Brunauer Emmett Teller (BET) and Scanning Electron Microscope (SEM). The results show that during calcination process, goethite is dehydrolyzed by removing structural water at about 300°C, which then transforms to hematite, and serpentine decomposes at around 600~700°C, leading to formulate olivine if agglomerating at higher temperature. By thermodynamics calculation, the goethite dehydration temperature is under 100°C, and about 200°C for serpentine decomposition. It might be the inclusions in ore which make laterite become hard to decompose.
The Application of High Strength Anchor about Compound Roof Support about in Guantun Coal Mine
Authors: Li Chun Ge , Duan Hong Min , Wang De Quan
Published: September 2013

50101 working face roof is typical compound roof in Guantun coal mine. Gateway design uses anchor-net + anchor rope supporting method. Sinking large roof abscission layer,the maximum abscission reached 450 ~ 500 mm Within one month after the construction .Anchor cable faults is frequently. In order to solve the above problem, We proposed to anchor cable φ15.24 mm changed toφ21.60 cable and Mining steel i-beam changed to W steel band . We can improve the support strength of anchor cable. With new support mode, We successfully make the roof abscission layer of subsidence and anchor cable fracture rate decline .
Studies of Mineralogical Characteristics on Vanadium Titanium Magnetite in Hongge Area, Panzhihua, Sichuan, China
Authors: Luo Jin Hua , Qiu Ke Hui , Qiu Yu Chong , Zhang Pei Cong
Published: September 2013

The composition, the texture and structure, the mineralogical characteristics of major minerals, the main occurrences of major elements and the distribution rules of vanadium titanium magnetite of Hongge area, Panzhihua, Sichuan Province of China, were studied in details by the methods of chemical multi-elements analysis, optical microscope, scanning electron microscope (SEM), electron probe micro-analysis (EPMA), X-ray diffraction (XRD) and X-ray fluorescence (XRF). The study results provide references to the vanadium titanium magnetite beneficiation process of this mining area.
Investigation of Temperature-Driven Ferroelectric Phase Transition via Modified Heisenberg Model: The Monte Carlo Simulation
Authors: Srinoi Sittidet , Laosiritaworn Yongyut
Published: September 2013

This work studies the temperature-driven ferroelectric phase transition of ferroelectric polarization under the absence of electric field. The modified Heisenberg model in three dimensions was considered and simulated via Monte Carlo simulation. The Metropolis algorithm and the periodic boundary condition were employed. The dependence of electric polarization on temperature was investigated to define the ferroelectric phases and their structural phase transitions. From the results, with well-defined set of relevant temperature parameters, the phase dependent polarization-behavior was found with a sudden change in its behaviors at the transition points. The structure factors were also considered and supported these phase changes. This conclusively pinpointed the important of temperature-dependent parameters in modeling ferroelectric materials.
Dependence of Neel Temperature on Ultrathin Film Thickness
Authors: Afremov Leonid L. , Petrov Aleksandr
Published: September 2013

Within the frame of average spin model the calculation of dependence of critical phase transition temperature in antiferromagnetic ultrathin films of different crystalline structure on their thickness has been carried out. I has been shown, that relative change of Neel temperature is subject to power law with exponent close to the experimental values.
Influence of NaOH Quantity upon the Size and Luminescent Property of Core-Shell Gd2O3:Tb3+ /SiOx Nanoparticles
Authors: Ou Mei Gui , Yang Chun Lin , Cai Shao Han , Perriat Pascal
Published: September 2013

Nanostuctured Tb3+-doped Gd203particles were synthesized from chloride precursors GdCl3and TbCl3by NaOH addition in a polyol medium. Then, Gd203: Tb3+particles were encapsulated in a polysioxane shell by being immersed in a mixed solution of APTES and TEOS. Effect of NaOH quantity on size and luminescent property of obtained core-shell nanoparticles was studied. The result shows that the size of nanoparticles increased with the increase of NaOH quantity from 30% to100% of stoichiometry. The emission intensity of core-shell nanoparticles increased with the size of particles due to the enhancement of energy transfer between core and shell.
Characteristics Study of Radio Frequency Sputtered TiO2 Films on ZnO Nanorods Grown by Hydrothermal Method
Authors: Chen Wei Ren , Lin Yang Sheng , Chen Huai Yi
Published: September 2013

In this study, we aimed at exploring a layer of radio frequency (RF) sputtered titanium dioxide (TiO2) film on a sputtered ZnO film treated by hydrothermal reaction and then conducted characterization of the film. The main objective was to discuss characteristics of the fabricated TiO2 films under conditions of different annealing temperature, film thickness, and oxygen flow rate. After measurement of four-point probe for the fabricated TiO2 films under the same film thickness or oxygen flow rate, their sheet resistance all became smaller through high-temperature annealing at 500°C, and the thicker the TiO2 film was, the higher the sheet resistance was. Under conditions of fixed TiO2 film thickness and annealing temperature, with increasing oxygen flow rate, the sheet resistances of sample thin films increased initially and then decreased. The sheet resistances became highest at oxygen flow rate of 4 sccm. Results, measured from field emission scanning electron microscope (FE-SEM), showed that the structure arrangement of TiO2 nanorods was affected by TiO2 film thickness, oxygen flow rate and annealing temperature. The stacking and blending situations between nanorods became severer for higher oxygen flow rate and annealing temperature above 400°C. In addition, grains formed on film surface apparently spread more outwards as the film became thicker.
Investigation on Recovery and Recrystallization of Al-Si-Al2O3 Composites
Authors: Wang Xiong Wei , Jiang Xiao Song , Zhu De Gui , Zhang Luo
Published: September 2013

Al-Si-Al2O3 composites were prepared by powder metallurgy with in-situ synthesis technology. The recovery and recrystallization behavior of Al-Si-Al2O3 composites which underwent compression and then heat-treatment under different temperature were studied using micro-hardness tester, optical microscope (OM) and scanning electron microscopy (SEM) . The results showed that the hardness of composites increased dramatically after compression, and the sample containing 5wt% Si was increasing more evidently than the sample including 10wt%Si. Heat treatment gradually eliminated work hardening; meanwhile the fact that the hardness of composites trended to decline greatly when subjected to annealing suggested occurrence of recovery and recrystallization inside the composites. Recrystallization nucleation preferentially took place in the region near the particle, while the growth of recrystallized grains can also be hindered owning to the pining effect of particles. Depending on the analysis of microstructure and microhardness, it can be concluded that the recrystallization temperature of Al-wt.5%Si-Al2O3 composites was 500°C and the Al-wt.10%Si-Al2O3 composites was 525°C.
The Study of Rheological and Mechanical Properties of the Antarctic Krill Protein/Sodium Alginate Fibers
Authors: Guo Jing , Li Xue Cai , Zhang Yu Yan , Zhang Li , Yu Chun Fang , Guan Fu Cheng , Wang Zhi Chao
Published: September 2013

protein was extracted from Antarctic krill (AK), then blended with sodium alginate (SA) , prepare the spinning solution, the rheological properties of spinning solution were studied by Brookfield DV-C digital viscosimeter. AKP/SA fibers were prepared via wet spinning with CaCl2 and PEG as coagulator .The morphology, tensile strength and thermal property of AKP/SA fibers were characterized by polarized light microscopy, monofilament strength tester and thermal gravimetric analysis (TGA) instrument. The result shows that the shear viscosities of spinning solution decrease with the increasing of shear rate and decreasing of concentration. the optimal Preparation Process of AKP/SA fibers were 5% concentration of SA, proportion of 1: 9 for AKP solution to SA solution, and proportion of 5:1 for CaCl2 to PEG. The cross-section of AKP/SA fiber is a jagged shape. Thermal property of AKP/SA fibers is similar to SA fibers.
A New Fast Multipole Boundary Element Method for Solving 3-D Elastic Problem
Authors: Gui Hai Lian , Li Qiang , Li Yu Gui , Yang Xia , Huang Qing Xue
Published: September 2013

In this paper, a new fast multipole boundary element method is presented. By using Taylor series expansion and a new mapping in boundary cell, the efficiency of calculation about influence coefficients has been improved. Compare with the old fast multipole boundary element method, this new method is easier to be suitable for the large-scale numerical calculus request.
The Influence of Modification Conditions on Activation of Coal Fly Ash
Authors: Song Hui Ping , Xue Fang Bin , Cheng Fang Qin , Guo Yan Xia , Cheng Huai Gang
Published: September 2013

The sodium hydroxide calcination-hydrothermal treatment was used to modify the fly ash in this paper. The mount of alkali, the ratio of solid and liquid and the temperature of calcination were respectively studied in the process of modification. The best modified condition is that the ratio of sodium hydroxide and fly ash was 0.4:1, the ratio of solid and liquid was 1:1, and the temperature of calcination was 400°C. The zeolite-like structure was generated after modification. The modified fly ash in this paper was cheap and effective, providing a theoretical basis for wastewater treatment.
Research Advances on Application Status and Non-Thermal Efficiency of Microwave Pyrolysis
Authors: Zhao Xi Cheng , Li Zhao , Jiang Yuan Ru , Xu Ke , Zhao Ya Juan
Published: September 2013

The progress of the application of microwave pyrolysis in China and oversea is reviewed. Introduce the methods and mechanism of produce high value-added chemicals through microwave heating of biomass, sludge and fossil fuel. And there should non-thermal effect existing in the microwave pyrolysis, and is worth to explore a way for the efficient fast pyrolysis of resources utilization of validity.
Study of Used Rolls Profile Influence on the Quality of Hot Rolled Metal
Authors: Krivtsova Olga , Viventsev Alexandr , Talmazan Vitaly , Musin Dinislyam , Arbuz Alexandr
Published: September 2013

The influence of used work rolls profiling on the quality of hot rolled metal was studied. The defect non-flatness is the main reason for hot rolled metal rejection to second grade at the continuous hot rolling mill 1700 of ArcelorMittal Temirtau JSC. The most optimal among studied profiling is concave profiling with average cumulative value ΣΔ=1.71mm. This is evidenced by the least volume of hot rolled metal, rejected to the second grade due to non-flatness.There were mathematical models developed, forecasting the volume of metal, rolled with the defect non-flatness with definite cumulative profiling of work rolls.
A Potential Biodegradable Metallic Material with Shape Memory Effect Based on Iron
Authors: Rațoi Mihaela , Stanciu Sergiu , Cimpoeşu Nicanor , Cimpoeşu Iulian , Constantin Boris , Paraschiv Ciprian
Published: September 2013

FeMnSi alloys are promising shape memory alloys which have been used for pipe joints but no previous work pays any attention to their biomedical application. Following the outline of the aforementioned development of biodegradable Fe-based alloys, we believe that it is worthwhile to investigate the feasibility of FeMnSi alloy as biodegradable metal candidate, since element Si is widely used in biomedical metallic materials as an alloying element. A shape memory metallic material based on FeMnSi was obtained through classical melting method. The material was analyzed as cast and plastic deformed through rolling concerning materials microstructure (scanning electrons microscopy - SEM), chemical analyses (X-ray analyze by EDAX) and corrosion resistance (or biodegradation rate) in an artificial saliva electrolytic solutions (Fusayama) artificial aerated by linear and cyclic curves determination (potentiometry - VoltaLab).
Determination of some Mechanical Characteristics by Vibration Testing of Welded Structures with Tubular Wire
Authors: Bereteu Liviu , Moisa Raul , Popescu Mihaela , Drăgănescu Gheorghe , Rosu Radu Alexandru , Burca Mircea
Published: September 2013

Applicability of the welded structures in different operating conditions requires experimental research developed in conditions previously imposed for each punctual application. There are analyzed in this case, in terms of vibration testing, some welded joints made with usual tubular steel wire. This is the case of the type carbon steel plates S235 JR according to EN 10025, with a thickness of 3 mm welded with MIG/MAG welding process with R713 tubular wire with a diameter of 1.2 mm, using SelcoNeoMig 3500 equipment. By processing the received signal based on the vibrations response to determine the elastic modulus of the welded structure, which will then be compared both with the modulus value obtained by tensile tests, and with the theoretical value obtained. The results thus obtained will be the basis of design, in optimal conditions of the welded structures regarding the appropriate behavior to the demands imposed.
Quality Requirements for the Design, Fabrication and Repair of Welded Vessels
Authors: Verbiţchi Victor , Dascau Horia
Published: September 2013

The Eurocode standards provide common structural design rules. The design is based on selecting minimum weight members to satisfy given conditions.
The standard applicable to the design of various tanks, vessels, containers and bottles for gas and liquid is: EN 1993-4-2; Eurocode 3; Design of steel structures; Part 4.2: Tanks.
For the verification of certain mechanical characteristics of such vessels, the applied standard is EN 1993-1-6; Supplementary rules for the strength and stability of shell structures.
Verification of the specific actions on structures, that imply dead and live loads, must be also applied for the tanks and vessels, according to EN 1991 and related standards.
Construction of welded vessels must be performed with qualified welding procedures. WPS/PQR and welder approvals (EN 287 and EN ISO 15614) are required. The longitudinal and circumferential joints must be butt-welded, both with full penetration. Tolerances, heat treatment and marking are indicated. Some examples of own realized welded vessels are presented.
Manufacturing inspection, by visual examination, must cover most aspects: bending, groove preparation, alignment before and after welding, welding process, penetration, tolerances for circumference, straightness and circularity, double-sided welds, heat treatment, small diameter welds around the nozzles, detecting of undercut, excessive convexity, distortions, etc. Defect acceptance criteria are presented, depending on the weld types and quality level, according to EN ISO 5817.
Macrographic examination according to EN 1321 of a transverse section of the welds, tensile test according to EN ISO 4136 and radiography testing of welds in accordance with EN 1435 class B are required. For pressure vessels, according to the ISCIR Technical Prescriptions, active in Romania, C 4-2010 „Static metal pressure vessels”, respective C12-2010 „Technical requirements for metal tank, container and barrel recipients for compressed, liquefied and solved gases, under pressure”, tightness and hydrostatic tests are performed at the maximal design pressure for 60 min.
For the stability verification, the ultimate limit state of local shell buckling should be applied, according to EN 1993-1-6, by the conventional method, stress design concept or global second order beam theory. The fatigue strength of the structural shell must be verified by the methods given in EN 1993-1-6.
Weld repairs are allowed, with no limit on the number and extent of defects. The repairs by welding are carried out according to ASME Code, Sections IX and VIII. According to the ISCIR Technical Prescriptions, a technology for repair welding must be elaborated by the manufacturer and approved by ISCIR.
The design, fabrication and repairs of vessels must be performed according to the mentioned standards, depending on the class of the vessel.
Crashing Behaviour Analysis of TWB Tubular Structures with Different Cross-Sections
Authors: Ciubotariu Vlad Andrei
Published: September 2013

The present paper investigates the crashing behavior and energy absorption characteristics of thin-walled (tubular) structures with different cross-sections made from tailor welded blanks (TWB) which were subject of axial quasistatic loadings. Resulted data were obtained by using explicit nonlinear finite element code LS_Dyna V971. Implementing the TWB into the auto industry was an efficient method to decrease the general weight of different structures. By far, these kind of bimetallic structures are largely utilized in auto and naval industries because it led to important decrease of scarp quantities and general manufacturing costs, improved material use and probably the most important, great fuel efficiency. After reviewing the literature it was concluded that proper combination between mechanical characteristics of sheet metals, different thicknesses and cross-section shapes into the same thin-walled structure is far too little researched and understood. The aims of this study are better understandings of the crashing behavior regarding thin-walled structure with various cross-sections made from TWB blanks subject to quasistatic loadings. The non-linear finite element platform LS_Dyna V971 was used for the numerical analysis of the crushing behavior regarding the thin-walled structures. Having two materials constituting the thin-walled structures, the crashing behavior changed during the quasistatic loading. Thus, the crashing inertia of the structure is somehow limited and controlled. It is noted that material ratio should not be randomly chosen due to the unexpected crashing mode which could aggravate the prediction and control of the crashing behavior of the thin-walled structure.
The Improvement of the Physical and Mechanical Properties of Steel Deposits Obtained by Thermal Spraying in Electric Arc
Authors: Toma Stefan Lucian , Bejinariu Costică , Gheorghiu Diana Antonia , Baciu Constantin
Published: September 2013

Steel depositsobtained by thermal spray arc have physical-chemical and mechanical properties dependent on operational parameters of the spraying process. Thus, the electric current intensity, the spray distance, the velocity, respectively the driving gas pressure are the parameters that influence the mechanical properties of the steel deposits obtained by thermal spraying. The interaction between particles- gas drive seen in the classic arc spray has the effect the lowering of particles temperature and implicitly of the physical and mechanical properties of the deposit. Using a new device, combined, in which over the thermal field, created by the electric arc, would overlap a second thermal field, created by a gaseous fuel burning, would determine the maintaining of high temperature of the particles and implicitly changes of the physical, chemical and mechanical properties of the deposit. Such a combined spraying device would be called device for spraying in electric arc-thermally activated. The paper aims to present a comparative study of the physic chemical and mechanical properties of steel deposits obtained with two spraying processes: the classical process and the combined spraying process - in electric arc thermally activated.Investigations carried out on the structure of deposits by electron microscopy SEM, XRD analysis and image analysis performed at zone level Layer-Substrate as well the deposits adherence assessment in accordance with EN 582-allows the highlighting properties, the arguing of differences between the properties of the deposits made by the two methods as well as the establishing advantages and disadvantages using those processes.
Peculiarities in Partial Melted Zone in Cast Alloys
Authors: Gheorghiu Diana Antonia , Toma Stefan Lucian , Mihordea Traian
Published: September 2013

The present work focuses on the microstructural changes that occur in the partial melted zone in welds made on some cast designated alloys. The aim of the work is to improve the available data related to PMZ morphology, properties and possible mechanism involved in the final metal response. It demonstrates that for binary alloys little changes occur in PMZ; in case of a complex alloy the changes are more consistent affecting both primary and eutectic structure when interstitials are involved. It proves also that the morphology of PMZ depends on the filler metal properties.
Composite Dowels in Bridges - Efficient Solution
Authors: Seidl Günter , Petzek Edward , Băncilă Radu
Published: September 2013

The bridges are vital structures for the transport infrastructure; it is a fact that, in the last decades, composite bridges became a well-liked solution in many European countries as a cost-effective and aesthetic alternative to concrete bridges. Their competitiveness depends on several circumstances such as site conditions, local costs of material and staff and the contractors experience. Beside the classical solution, the new ones with efficient design and construction improve and consolidate the market position of the steel construction and steel producing industry. These bridge solutions combine many important aspects: reduced costs, fast and simple erection, durability and robustness, low maintenance costs and an appealing aesthetical aspect. Another feature is the robustness of composite bridges. The robustness of a structure has to be defined as being the capacity of the system to keep its structural integrity for any kind of action that may occur during its service life. The present tendency in composite bridges consists in simplifying the structure as much as possible. Continuous shear connection using a cut steel strip is a solution for composite beams. With the introduction of the composite dowel the possibility is given to develop new construction methods for bridges. The paper will include interesting aspects regarding the dimensioning of the structure and technological features and also aspects related to the efficiency, robustness and fatigue behavior of the joints with composite dowels in bridges. The behavior of the dowels has a theoretical background based on laboratory investigations. The Romanian railway and highway infrastructure is presently involved in a large operation of renewal and modernization. The solution was recently introduced in Romania for three highway bridges of medium spans.
Pulsed Laser Welding of Automotive Advanced High Strength Steels Thin Sheets
Authors: Bîrdeanu Aurel Valentin , Ciucă Cristian , Joni Alexandru
Published: September 2013

The need of cost and weight reduction trend present in the automotive industry lead to the implementation into automotive sector of new materials categorized as Advanced High Strength Steels (AHSS). The use of these materials requires the development of appropriate joining technologies, e.g. pulsed laser welding.
The paper presents the results of the development of overlap joints realized by pulsed laser welding technologies of Zn coated AHSS. The statistical influence of the main process parameters was investigated by means of factorial experiment design weighted towards the shear strength results. The influence of laser pulse peak power, the joint gap, the travel speed and the position of the focal point were investigated for three types of AHSS with different thicknesses. The results reveled that the base material thickness influences the importance of the investigated process parameters with impact onto the maximum obtainable shear strength values.
Thus, with the thinnest plates, the travel speed is the most important process parameters then the joint gap starts to have also an important role, and for the thicker plates the joint gap becomes the most important influence factor – a phenomena which can be related to the Zn vapour expulsion.
Deconstruction of Existing Railway and Highway Bridges
Authors: Petzek Edward , Toma Luiza , Meteş Elena
Published: September 2013

The paper presents the damage under time dependent actions, fatigue, creep, corrosion for a railway bridge and a highway bridge. The first one is situated on the IV Pan-European Corridor, which crosses the Romanian territory. Although recently rebuilt, in the end of 80s, the bridge’s superstructure, made of decks with twin plain web girders, was in an unsatisfactory condition - loss of load bearing capacity and missing structural parts (strong corrosion and cracks). After the stress analysis and the fatigue verifications based on the Wöhler concept which were made in relation with the prescriptions of the Romanian standard SR 1911-1998, Swiss code 161 & SBB Richtlinie 2002 and the German code DS 805-2002, a life prediction analysis based on fracture mechanics principles was performed in order to evaluate the remaining fatigue life for this structure for the new traffic UIC conditions; in conclusion, the superstructure should be replaced. The highway bridge is the only crossing possibility over the Bistriţa River, parish Frânceşti, being an important element for the road infrastructure in the area. The current bridge was meant to be a temporary structure, but due to economic difficulties it wasn’t replaced. It does assure the clearance and safety according to the standards. Based on the technical situation of the existing bridge the replacement of this structure is a necessity. Taking into consideration the need of a simple technology, the limited construction height and a very short erection time, it leads in both cases to the necessity of a modular system with low costs. In this area of application the VFT-WIB® solution with its roots in the classical WIB composite structure was developed.
Modeling of Heat Transfer in Pipeline Steel Joint Performed by Submerged Double-Arc Welding Procedure
Authors: Birsan Dan Catalin , Scutelnicu Elena , Visan Daniel
Published: September 2013

Submerged arc welding is the most applicable and productive procedure when thick sections have to be welded. Nevertheless, the manufacturers of pressure vessels, pipelines, ships and offshore structures keep on looking for new and modern design solutions of equipments and technologies which should lead to increase of welding process productivity. For instance, the longitudinal welds of pipelines are, mostly, performed by submerged arc welding procedure with multiple arcs and/or multi-wires, such as twin, tandem or twin-tandem, in order to increase the process productivity. However, achievement of optimal mechanical properties of the welded joint should remain the most important quality criteria. It is well known that dependence of the mechanical and metallurgical changes on heat transfer plays a major role in obtaining of safe welded structures and preserving of their structural integrity. That is why the investigation of heat transfer induced by the welding process is required. Furthermore, setting of distance between thermal sources and its influence on the overlapping phenomenon of temperature fields should be explored when submerged double-arc welding procedure is applied. Three dimensional finite element model of butt welded joint - used for simulation of heat transfer in pipeline steel joint performed by submerged double-arc welding process - is developed and described in this paper. Numerical results and a comparative analysis related to the temperature distribution, thermal history, and temperature variation in cross section of the welded joint at different time steps are discussed. Finally, important conclusions regarding the influence of distance between thermal sources on thermal effects and temperature fields overlapping are drawn.
Experimental Results on Micrometric Profile of Substrate and Thickness and Roughness of Deposited Layers through Thermal Spraying
Authors: Arghirescu Adriana , Baciu Constantin , Cimpoeşu Nicanor
Published: September 2013

Thermal spraying is composed of a group of processes in order to obtain thin films, where fine powders, metallic or nonmetallic, will be deposited in molten or semi-molten state to form a coating layer with the properties required for use. Few layers of stainless steel on usual steel substrates were deposited through thermal spraying deposition in different conditions. As anchor layer a nickel thin film was used between substrate and external layer. The materials surface was analyzed through scanning electrons technique using a VegaTescan LMH II microscope. Thermal metal spraying in electric arc was performed at different working distances which influenced the surface roughness of the deposited layers. To highlight these issues, the parameter of roughness (Rz) and (Ra) measurements were made of the corresponding obtained surfaces. Due to the fact that macroscopically it was noted an increased roughness, it was necessary that the experimental investigations to be conducted on a Taylor-Hobson equipment, model FormTaly Surf 50 (AMTEK, USA).
The Comparative Analysis of the Concentration of Microparticles during Mechanized MAG Welding Using Cored Wires
Authors: Mihailescu Dănuţ , Frincu Octavian , Gheonea Marius Corneliu
Published: September 2013

Use of cored wire - shielding gas (gas mixture) pair, during mechanized MAG welding, causes the microparticles formation which is harmful for the welder’s health. The paper presents the experimental method for determining the concentration of the microparticles generated during MAG welding when rutile cored wires (standard and low fume emission) and metal powder cored wires (standard and low fume emission) are used. Carbon dioxide and the shielding gas mixture are investigated, too. Four types of cored wires were comparatively analysed, when three wire speed values were applied. The research of the microparticles concentration was conducted after each welding bead deposition, at the upper part of the welding enclosure, using MicroDust Pro particulate monitor. After each weld bead was deposited, the metal frame of the welding enclosure was removed, and, the fumes and gases, produced during the welding process, were eliminated through two fans, positioned inside and outside of the equipment. Using rutile cored wire with low fume emission, a decrease of microparticles concentration up to 30% is noticed in comparison with standard rutile cored wire. Using metal powders cored wire with low fume emission, the microparticles concentration is diminished with 12.5% comparing with standard metal powders cored wire.