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Dielectrophoresis (DEP) has been verified to be an efficient means of assembling carbon nanotubes (CNTs) for various applications. This paper simulates the electric field distribution of the quadruple electrode structure when the external AC voltage is applied between a pair of opposite electrodes. There exist induced electric potentials between high voltage electrodes and floating electrodes and thus floating electrodes seriously change the field distribution. For a pair of wide parallel electrodes, the deposition of one CNT bridging the electrode pair will greatly alter the local electric field and repel the further deposition of CNTs in the vicinity. The screening distance is relevant with the width of the electrode gap, which provides a way to estimate the density of assembled CNTs between the electrode pair.

Displacement is traditionally deemed to be equivalent to deformation. However, displacement is not exactly deformation, for example, the tip of a workpiece illustrates big displacement, but, it caused by the deformation of main body. In this paper, theory of active and passive deformation is proposed for the evaluation of the deformation of workpiece during heat treatment process and the corresponding algorithm was established. The deformation consists of active and passive deformation; the former is the actual deformation, while the latter is caused by the deformation of other areas. This algorithm was applied to the deformation analysis of a hydraulic turbine blade which is a large thin-walled workpiece. And the real deformation area of the blade is found.

In this paper, the keyhole of YAG laser welding 5A90 Al-Li alloy was observed and measured through the high speed camera. The characteristics of the keyhole and the effects of welding parameters were studied. The characteristics of the absorption of laser energy and the susceptivity for heat input in welding 5A90 were given. The results show that in this welding condition, the keyhole of laser welding 5A90 is nearly a taper and the highest temperature area is in the bottom. There are clear effects of heat input on the characteristics, especially the surface radius of keyhole and plasma/vapor in keyhole. Another phenomena is observed that sometime plasma/vapor could disappear in 0.3ms welding time, and this feature will be more remarkable as decrease of heat input. It shows that the absorption of energy is unsteady. It is known that when this instability reaches a certain value, an unsteady weld will be formed.

This paper presents the results of dilatometry and DTA analyses performed on a Ni base super alloy sample on which a ZrO2/20%Y2O3 coating was deposited. The tests were done at similar temperatures as those present in a gas turbine engine at the inlet of the turbine. The purpose is to assess how a turbine blade with a ZrO2/20%Y2O3 coating would behave to changes in volume due to temperature and structural changes. The differential thermal analyses and thermo gravimetric analyses were performed on the DTA PT 1600 Linseis installation. The thermal dilatometry was performed on the L75HX XXXX installation.

The use of aluminium alloys rose in the last decade, as its specific mechanical properties allow a reduction of mass as for example in automotive. Moreover aluminium, due to its high corrosion resistance, is a very important material class in plant construction, where it is used for pipes or container till 250 °C. Aluminium can be welded with different technologies. Nowadays TIG and MIG are mainly used for example in plant construction or in mechanical engineering. Laser beam welding is a widely established technology in automotive. The advantage is the high energy concentration, which leads to a high welding speed and a narrow heat affected zone. Plasma welding is applied when joining aluminium with alternating current, as an easy removal of the oxide layer in the surface of the weld pool is possible. Plasma-Powder-Arc-Welding (PPAW) method has been developed from Plasma Transferred Arc (PTA) weld surfacing and Plasma Arc Welding (PAW) methods by combining a small PAW torch (PAW is traditionally performed with wire as filler material) with powder filler material feeding as used in PTA-equipment. The coupling leads to a better mechanisation of the welding process as the consumable is fed directly through the welding torch. In this paper investigations on aluminium sheets (£ 2 mm) AA5xxx and AA6xxx using different powder materials are reported. The influence of the processing parameters and conditions on the process reliability, when welding with industrial robots butt and corner welds is investigated. Conventional PPAW of aluminium is performed with AlSi12 filler material. A post processing of the joint, as for example anodising in order to improve corrosion resistance, leads to a very different optical aspect, as the colouration of the weld seam after anodising differs from the base material. Thanks to a correct choice of filler material it is possible to reduce the colour differences between base materials/heat affected zone and bead, so that the weldment can be set for high quality optical applications, too.

This paper briefly reports on the improved properties and bettered applications of some piezoelectric ceramics (i. e. S-PZT, etc.) of ferro/piezoelectric community by means of bettering their technological process links, especial superfine grinding of powder of raw materials, and sintering technique of piezoelectric ceramics in them. These piezoelectric ceramic materials have obtained the better effect in their newly and widely applied aspects, such as, acoustoelectric transducing; electrical to mechanical to electrical transducing; acoustooptic effect; electrooptic technique, and, piezoelectric ceramics for high voltage generators, ignition and detonation purposes, and some original applications (e.g., combining the electrorheological fluids) etc.. As far as appropriate measure of the improving sintering and other technique processes in present work is concerned, they also have reference value to electronic ceramics of having similar manufacturing technological process, such as capacitor ceramics, resistance ceramics, magnetic ceramics, and oxide ceramic superconducting materials, etc..

Evaluated with the yield of litsea cubeba essential oil, water extraction technology of essential oil from the seed of Litsea Cubeba (Lour.) Pers. assisted by microwave and ultrasonic is studied for the first time in this paper. The optimal water extraction technology of litsea cubeba essential oil assisted by pure microwave is as follows: extracting time 40 minutes, microwave power 650 W, solid-liquid ratio 1:4 (g/mL). Average yield of litsea cubeba essential oil is up to 10.287% (g/g) under the above optimal technology. The optimal water extraction technology of litsea cubeba essential oil assisted by microwave together with ultrasonic is as follows: extracting time 8 minutes, microwave power 600 W, solid-liquid ratio 1:7 (g/mL), extracting temperature 85 . Average yield of litsea cubeba essential oil is up to 14.188% under the above optimal technology. Microwave and ultrasonic can effectively enhance the extraction process of litsea cubeba essential oil.

This paper mainlyintroduces the basic optical principles of light. Using He-Ne laser and pinhole configure collimated illumination, measuring the index of refraction by minimum deviation method, and measuring the birefringence use of wedge method by transmission optical microscope. In addition, give the results and discussion of the whole experiments.

Zinc coated steels are nowadays used for different applications as for example for household appliances, automotive or offtakes. Due to the boiling temperature of zinc (907°C), which is lower than the steel melting point, the welding of zinc coated steel sheets presents many difficulties. As a result of the violent evaporation of zinc, pores in the weld seam are present after solidification and the zinc coating near the weld is damaged. Brazing of zinc coated steels with CuSi-alloys offers some advantages, as the joining temperature is about 950-1000°C. Nevertheless the high melting point of these filler materials requires very restricted process strategies and damaging of the zinc coating near the brazing seam can’t be avoided. Although laser-, plasma- and MIG-joining with CuSi and CuAl are performed nowadays. ZnAl-alloys are characterized through low melting temperature, which are comparable to the melting point of zinc, so that the damaging of the zinc coating can be reduced. In this paper investigations carried out with ZnAl-materials for joining zinc coated steel sheets as DC04ZE75/75 and DX56Z (thickness 0,9 mm) are reported. First investigations were performed by resistance spot soldering and show that using low temperature melting materials leads to a lower damaging of the zinc coating. Further the process reliability of laser soldering with ZnAl-alloys and a Nd:YAG as well as a diode laser is reported and confirms the suitability of these alloys for a damaging free joining zinc coated steels. The low surface tension leads to a wide bearing section, so that advantageous properties are expected. The mechanical properties of edge welds are evaluated in this paper through tensile tests as well.

Compared to welding, laser brazing offers a suitable possibility to lower the working temperature and to join unweldable material combinations, while maintaining the numerous advantages of the laser joining process. Beside an acceptable joint strength, the brazed joints are characterised by a smooth surface and seams with almost no pores. As a result of this laser brazing combines the advantages of conventional brazing and laser welding. Within the scope of this paper the laser brazing process and its characteristics are explained in detail. In particular the interrelation of temperature progress, available processing time for brazing/diffusion and the thickness of the diffusion layer is discussed. Subsequently the material specific particularities of laser brazing aluminium alloys are described and discussed with respect to recently gained results.

Against the background of the required weight reduction in transportation through lightweight construction, the application of hybrid structures, where dissimilar materials are joined together, has a high technical and economical potential. In the field of sheet machining, combinations of steel and aluminium are especially interesting. In comparison to conventional steels, the application of aluminium alloys as supporting materials makes a distinct weight reduction possible. On the other hand, steels have advantages in the fields forming and welding. The application of modern high-strength steels with reduced sheet thicknesses allows weight reduction, too. But joining of material combinations of steel and aluminium is problematic. On the one hand brittle intermetallic compounds are formed between steel and aluminium. On the other hand the aluminium melt has a bad wetting behaviour. Different physical properties of both materials have to be considered, too. To achieve sufficient mechanical properties of such joinings it is necessary to limit growth of intermetallic compounds between steel and aluminium. This can be actualized by an exact energy supply. With the electron beam on atmosphere a precise and easily controllable energy supply is possible. The publication demonstrates successful investigations, which were performed with the 175 kVNVEBW (Non Vacuum Electron Beam Welding) installation at Institut of Materials Science, University of Hanover. With NVEB joining hybrid structures between zinc coated steels and 5.xxx and 6.xxx aluminium alloys were produced. In a welding-brazing process (the steel remained in the solid phase whereas the aluminium was molten) combinations with acceptable mechanical properties could be joined. By use of optimized joining parameters as well as a surface activating flux, both, a good wetting and a thin intermetallic compound < 10 µm were attained. Another possible strategy is a pure brazing process, for which an example is also given in the paper. The paper shows metallurgical and mechanical investigations, among other things results of element distribution analysis and tensile tests.

The customers’ demand for high quality and low cost products with rising functionality forces the enterprises to cost savings. In production these cost savings can be accomplished by simplification or omission of handling operations in the process chain. In laser beam welding of stamped sheet metals a previous cleaning of the sheets is usually necessary to guarantee a sufficient seam quality at a lap joint. Due to the recent trend towards low use of lubricants in forming operations the question arises, whether this process could be avoided in order to lower the production costs. The disadvantage of this measure would be a degradation of the seam quality. This reduction shows up in a falling strength of the weld due to inclusions and pore formation. This paper deals with the impact of different types of contaminations on the quality of laser welding. Therefore several liquid (oils) and solid (metallic and non-metallic) contaminants are examined. Zinc coated sheets are investigated too, because a zinc contamination arises with these sheets in the welding operation. The zinc coating evaporates because of the high temperature and this leads to a high porosity in the welding seam. In both cases also the height of the gap between the two sheets is varied in order to investigate its influence on the weld. To reduce the effort of the investigations, but not the accuracy of the results, the laboratory trials were supported by the methods of design of experiments. After the welding operation, the quality of the welding seam is evaluated by means of its mechanical properties and tightness. The results of the investigations are discussed and the developed solution strategies are presented.

During the joining process of complex body components in the automobile industry, dimensional accuracy is essential. In order to predict the behavior and to improve the geometrical quality of joined sheet metal parts during the welding and cooling process, a simulation method by means of finite elements is applied. This should be done in the early stage of the product’s life cycle to reduce process adjustments, which are time and money consuming. In recent years the simulation of welding was basically feasible by models consisting of volume elements. This way the metallurgical phase transformation, which is responsible for the behavior of the treated parts during the cooling process, can be established for a specific material. The use of volumes has a negative influence on the calculation time and it is not applicable for sheet metals. Especially, if effects from previous forming processes are to be considered. Additionally, the application of shells can meet the requirements of an analysis of the effects of welding when the metallurgical material properties are taken into account. In this paper an example of a sheet metal (DC04, former St 14) will be examined with the aid of a finite element analysis. Firstly, a transient temperature field is calculated in a thermal simulation by applying a certain method. In this calculation only the thermal properties of the material are used. Secondly, the transient temperature field is used as the initial load for the thermo-mechanical analysis. The distortion and the residual stresses of the work piece can be calculated using thermo-mechanical properties and material phase transformations.

A new process technology for stretch-forming of thin sheet metals is presented within this paper. This new technology is based on shock waves as a source for the forming energy, which are created through laser pulses. The results of some preliminary experiments show, that stretchforming with laser pulses is possible. The influence of parameters like defocussing, power density, pulse energy, number of pulses and material are worked out with excimer-laser pulses. The results show, that uniform shaped domes with a dome height over 250 µm with diameters of 1.4 mm could be produced. More recent studies show that even better results can be reached through the use of TEA-CO2-Lasers, since no confinement is needed and ablation at the surface is avoided. The absence of ablation at the surface makes this new technology even more interesting, since not only the surface remains accurate, but also since several pulses can be applied at one point and thus higher forming degrees can be reached without increasing the power density.

In the paper the thermal characterization of friction stir welding processes (FSW) of aluminium alloys is presented. In particular both embedded thermocouples and a thermography analysis were utilized in order to acquire the temperature vs. time curves in point of interests of the joints and the temperature distributions, respectively. Such kind of results are very important in order to investigate the material conditions during the FSW process.

In the paper the results of a wide experimental activity on friction stir welding (FSW) of aluminum alloys are reported. In particular the butt joints of two different materials, namely AA1050-O and AA6082-T6 were considered. Grains dimensions and precipitates density were investigated both in the parent materials and after the welding processes. Furthermore post-welding heat treatments effects on the joint strength were studied.

The multifarious applications of aluminum alloys in different industrial domains are based on the mechanical properties as well as the light weight characteristics, which allow energy saving for the products in use. Nevertheless aluminum alloys are considered to be difficult to weld by conventional welding processes. This paper deals with cost-effective friction stir welding of thin sheet aluminum alloys in thicknesses of about 1 mm to widen the possible range of applications. Based on former studies results will be shown how an optimized tool geometry increases the mechanical properties of friction stir welded parts. The characteristics of these friction stir welded thin sheets will be analysed in a statistical evaluation in order to detect the interactions and dependencies of the process parameters. By highlighting the main process parameters and their significances a process window for friction stir welded blanks of AA5182 and AA6016 is presented.

Recent developments in infrared camera technology, testing methods and data processing algorithms have brought significant progress for high resolution spatial and temporal analysis of thermal radiation. Together with industry standard automation technology and specific infrared image data processing it became possible to non destructively inspect laser welded seams and other types of joints using heat flux analysis subsequent to thermal stimulation. High thermal diffusion coefficients of the usually metallic samples under test make the availability of high-speed infrared cameras as a key hardware component indispensable. Since high-speed infrared cameras with frame rates of at least 500 Hz have become available for commercial applications, non-destructive testing systems with a new class of performance were designed, manufactured, and implemented at industrial sites. Heat flux analysis as a new and robust method of non-destructive testing has been implemented for various types of equipment, ranging from off-line tools for laboratory use to automated robot based systems enabling fast and operator-free in-line inspection. Depending on environment, implementation surroundings, and geometry of objects to be inspected, different types of pulsed or continuous operating heat sources (e.g. flash light, laser, … ) are selected. Due to its outstanding industrial relevance non-destructive testing of laser welded seams in automobile manufacturing is shown in detail in this paper.

This paper renders research into the fundamentals governing the melt pool dynamics of a hybrid bifocal laser welding system consisting of an Nd:YAG and a high power diode laser (HPDL). The resulting superposition of keyhole by heat conduction mode welding is assayed for extruded aluminum. In particular the diffusion of the surface oxygen layer is considered. By comparing the results attainable by bifocal laser hybrid welding to the constituent laser processes synergetic effects of the laser hybrid can be demonstrated. These are namely the doubling of the welding speed from 2.0 min-1 to 4.0 m min-1, the reduction of the roughness of the weld surface from 60 om to approximately 10 om and an increase in energy transfer efficiency. The experimental investigations verifying these synergies are outlined and discussed.

A novel fibre optic sensor system has been developed for detection of acoustic emission. The sensor design was based on a 2×2 fused tapered optical fibre coupler configuration. Given the intended use of this sensor for the detection of acoustic emission in smart materials and structures, its lightweight, compatibility with composite material and immunity from electromagnetic interference are great advantages. Apart from the performance specification and reliability, the overall cost of the sensor system is a major factor in their adoption by end-users. The manufacturing of this sensor is low-cost and the signal output from the sensor system developed can be directly fed to the commercial AE acquisition system. The demonstration of acoustic emission detection was conducted using fibre coupler-based AE sensors in different materials and structures. The AE sources are various and depend on the different applications. In the current paper, we report on the use of the fibre optic AE sensor system for concrete damage monitoring. An experiment on damage detection on a composite plate with this fibre optical AE sensor is also reported in the paper.

This paper describes the analysis of thermal and mechanical effects during welding and the following cooling-phase on a welded structure. An off-the-shelf aluminum-profile, as used in other simulation sub-projects of the research center, was chosen as a sample part for the simulation tests. Taking up an important production scenario of lightweight-production, the frontal closing of two profiles is modeled. The development of residual stresses and the distortion is investigated by a thermo-mechanical FE-simulation. The virtually examined process is provided by a hybrid, bifocal laser system consisting of both an Nd:YAG-laser and a high power diode laser (HPDL). For comparison, a single Nd:YAG-process was simulated, too. The theoretically different generation of residual stresses can be verified within the simulation.

It is known that the basic mechanism of fatigue crack growth in ductile pressure vessel steels, which is repetitive blunting and re-sharpening of the crack tip, is a weak acoustic emission (AE) source. On the other hand, a large number of AE events occur during cyclic crack growth. Most AE events are caused by repetitive friction at the fracture surfaces, but these AE events show relatively weak correlation with the crack growth velocity. In the paper it is shown, based on examples – fatigue crack growth starting from an artificial weld defect, cycling of a natural crack defect, crack initiation and growth in gas cylinders - which information can be gained by relatively simple analyses of the AE data from cyclic pressure tests.

We research the new thin film transformer equivalent circuit modeling, simulate and modify the traditional estimate formula of the transformer equivalent circuit parameters, in order to attain the automatic extraction of thin film transformer parameters. This paper used MATLAB and Agilent ADS on the thin film transformers for the S parameter simulation. The simulation results show the estimation has better accurate and universal, it also shows the effect of different number of turns and thin film materials on the properties of thin film transformer.

A moisture-measuring device for the determination of percentage moisture content of cassava particulate on dry basis during drying process was developed used to investigate the effect of pressure on the resistance of the cassava particulate sample. A thermo-gravimetric sample analysis was used for the calibration of the moisture measuring device. The device had four electrode cups, two of which were used as dummies to give a ½ Wheatstone bridge circuit used to measure the resistance. The resistance of the cassava samples increases with decrease in the %moisture content and decreases with increase in pressure.

This study presents the experimental results of using admixture of used engine oil and kerosene as an alternative fuel in foundry shops. In this experiment, several proportions of used engine oil (well filtered) and kerosene were measured to make 1000ml per mixture using a calibrated beaker. Each mixture was fired in a furnacensuring atomization, ignition and combustion in a timed set up. Results of the experiment showed that admixtures of 100%, 95% and 90% volume of used engine oil gave low pour point hence were incombustible. 85%, 80% and 75% volume of used engine oil admixtures gave carburized flame. While 55% and below of used engine oil volume of admixtures gave oxygenated flame. 57% - 70% volume of used engine oil admixtures produced neutral flame which is ideal for melting. Of the latter proportions, 70% of used engine oil admixture had the highest heat content 70,780 kj/kg and the lowest cost. Hence this admixture is recommended as an effective admixture for fuel substitution in the foundry shop.

This paper presents the processing flow and results of optical fabrication for an optical correcting lens with a free-form surface, namely a free-form lens. Because a correcting lens has no rotation axes of symmetry and its surface cannot be expressed by a continuity equation, its processing technology is different with that of general aspheric lenses. The correcting lens was firstly formed from a glass workblank with flat face using diamond abrasion wheel with spherical shape, and then loose abrasive lapped and polished with oblique axis spherical tools to decrease the surface roughness and increase the surface accuracy based on the measuring result after forming. At the lapping and polishing stages, two processing methods are employed. One is to control the processing pressure, and the other is based on dwell time. Since high precision fabrication is closely related with high precision measuring, this paper also presents a high precision non-contact optical measuring method based on image transforming for correcting lenses. The effectiveness of the processing flow and technology is confirmed by an experiment in which a workblank is processed into a satisfying correcting lens.

Laser surface texturing (LST) technology that is firstly used in rollers, is a specialized surface engineering process capable of enhancing the surface material properties, wear resistance, fretting fatigue life and reducing friction. This practical technology of the LST process is based on a pulsating laser beam that, by material ablation, generates the optimum topographical surface. In order to exploit the full potential of the process, a great amount of research has explored from the material removal mechanics to the development of the LST process. This paper reports on the LST research involving the LST technology surveying process optimization, LST equipment and its industrial applications. The paper also highlights the forming theory describing the skin-pass process of transferring the textured roller’s surface structure onto the steel sheet, and the laser-matter interaction that occurs when and intense laser beam is tightly focused in the workpiece surface. It presents the influence of various factors affecting the textured workpiece performance together with the investigations into tribology of textured components. The paper also discusses these developments and some fundamental on future LST research.

The functional crystal material Potassium dihydrogen phosphate KH2PO4 (KDP for short) is widely used in navigate, spaceflight, national defenses, energy sources and information technology fields because of its excellent non-linear optical property. However, KDP crystal has some disadvantages such as soft, fragile, hygroscopic, anisotropy, thermally sensitive and low rigidity, which make it a most difficult processing material. In this paper, KDP crystal was machined by the wheel grinding. Some equipment, such as Optic microscope, SEM, ZYGO and Raman spectroscope were used to observe and analysis the KDP crystal surface which was damaged during grinding. The results shows that serious nicks, crashes and the press stress appeared on the surface of the KDP crystal after grinding.

In this paper is revealed the structural transformations and diffusion processes that take place as a result of the local thermo-mechanical treatment regimes specific to friction welding of nitrided and not nitrided quenched and tempered steels. To obtain welded joints with good mechanical properties it is necessary to remove the nitrided layer from the contact surfaces.

The paper presents the experimental results regarding the influence of the multiple thermal cycles on the structural and mechanical characteristics of the weldable C-Mn steel used in energetic. Macro- and microscopic examinations, and mechanical testing made on the intersection welds show that the structural and mechanical characteristics are within the reference range of CMn (type S355JR) steel. So, the hardness of the pearlitic – ferritic structures in the welded joints characteristic zones is less than 216 HB; the tensile strength of the welded joints is more than 430 [N /mm2], imposed value for the C-Mn steel. Also, the weld toughness is between 38 [J] and 52 [J] (at 20 °C), more than 27 [J], value what must be assured for the investigated steel. So, the tendency to brittle fracture of the welded joints is diminished. The presence of some imperfections within the intersection welds imposes a carefully monitoring of all these welded joints by adequate nondestructive examinations.

Laser welding process is widely used in the industrial field due to its numerous advantages: a small heat affected zone(HAZ), deep penetration, high welding speed, ease of automation, single-pass thick section capability, enhanced design flexibility, and small distortion after welding. In this paper, the laser weldability of Austenite stainless steel and INCONEL600 at dissimilar metal welds using a continuous wave Nd:YAG laser are experimentally investigated. INCONEL600 is being used in a steam generator tubing of pressurized water reactor(PWR) exposed to some corrosion. Therefore stress corrosion cracking can occur on this material. A research work is conducted to determine effects of welding parameters, on eliminating or reducing the extent welding zone formation at dissimilar metal welds and to optimize those parameters that have the most influence parameters such as focus length, laser power and welding speed were tested.

The practical uses of soft magnetic composite(SMC) for an electrical motor is presented in this paper. SMC allows obtaining improved stator and core shapes as well as totally new design concepts such as claw pole motor. However, a major disadvantage of soft magnetic composites was their weak strength. In this study, spark plasma sintering (SPS) was utilized to improve the strength of SMC. Advantages of the SPS process over other conventional sintering process are the faster heating and cooling rates ensured and higher pressure applied during the sintering procedure. This allows obtaining high strength products in short periods of time to meet with industrial application without insulation destruction. This paper introduces the development of high strength soft magnetic composite motor core and examples of practical application for industries. The result showed that the SPS process increased the fracture strength, about 1.3 to 1.7 times, of SMC compare to the conventional compaction. Also we derive method to reduce the iron loss in the SPS sintering process using control forming temperature. As the forming temperature decreased from 500°C to 300°C, reduction of iron-loss was obtained from 192W/kg to 21W/kg by using SPS sintering process. Moreover, with increased the SPS sintering process pressure value from 250MPa to 800MPa which is the conventional compaction condition and decreased forming temperature to 200°C, iron-loss was measured. The results showed that iron-loss was obtained 11.42W/kg and it was similar value of conventional compaction results.

In this paper we report the preparation of carbon nanotubes (CNTs) by ethanol catalytic combustion (ECC) technique. We employed cobalt salt as catalyst precursors, copper plate as substrate and ethanol as carbon source. In order to have a better understanding of the growth mechanisms, we employed cobalt chloride, cobalt nitrite and cobalt sulfate as catalyst precursor to study the influence of catalysts on CNTs growth respectively. Entangled and nonseparated CNTs were aggregated together when the catalyst precursor was cobalt chloride, while straight and uniform CNTs were obtained when the catalyst precursor was cobalt sulfate. In the case of using cobalt nitrite as catalyst precursor, the CNTs tend to form helical and disordered structure. We have examined the morphology and microstructure of the obtained CNTs and discussed the growth mechanism.

This paper presents experimental and numerical simulation for deformation and fatigue life prediction of various cables, such as electrical, optical and network cables. The cable damage is produced by the tensile, bending and torsional action under moving and fixing condition, and by direct external impact. To obtain material responses of the cable, uniaxial tensile tests and drop-weight impact tests were adopted, and the nonlinear constitutive equations based on various strain energy potentials or material models were employed to analyze deformation of polymer sheath and metallic armor layer of the cable. Finite element results were compared with experimental data for deformation and impact absorption energy of the cable during direct external impact. Also, fatigue strength of the cable was predicted from variation of calculated stress level under tensile conditions. Fractured surface of the cable were analyzed by scanning electron microscopy (SEM).

Aluminum foam is lightweight structures, energy absorption and thermal management. In this reason, there is a lot of attention on the aluminum foam as a structural material. The present papers showed various conventional joining techniques can be applied for foam-sheet structures, i.e., riveting, screwing, welding, gluing and soldering. This research presents new joining technique of Aluminum foam/Aluminum metal using spark plasma sintering (SPS) process. The Aluminum foam/Aluminum metals were fabricated by changing of various SPS holding temperature and holding time conditions. With increasing holding temperature and holding time, the tensile stress increased. The specimen sintered at 550°C for 20 min shows σts = 1.47 MPa. Also, it was found that the SPS holding time is dominant factor than the holding temperature for sound joining of two joint materials.

In this paper, we present the theoretical investigation of index-coupled distributed feedback (DFB) laser with tilted single mode ridge waveguides. By tilting part of the ridge waveguide in various degrees, DFB laser with manifold effective grating periods can be realized. The structure is analyzed using couple mode theory in matrix form based on threshold analysis. Important parameters of DFB laser like resonant frequency and threshold gains are obtained by solving the eigen-equation. The results indicate not only that the lasing frequency is modulated by the waveguide titling angle, but also large Gain Margin (GM) can be achieved at the threshold condition which enhance the stable single mode operation in index-coupled DFB laser.

In this study, we found out the new fabrication process condition for Photonic crystals(PCs). PCs were fabricated by holographic lithography(HL), instead of commonly used electron beam lithography(EBL). HL process enable periodic large area fabrication of PCs. Also this method can easily control the pitch of periodic patterns. We set up holographic lithography system by laser and some optical components. The source of light used laser of 442 nm wavelength. Photo-resist(PR) used DMI-150 model. The viscosity of PR is diluted with propylene glycol monomethyl ether acetate(PGMEA) which is solvent for DMI-150. This experiment is holographic lithography of rotated double exposure method for PCs pattern. The method use only one beam. Result data is shown by atomic force microscope(AFM), scanning electron microscope(SEM) and 3D contour image. At the this study, we conclude conditions which we need periodic structure for PCs. It is some factor. For example, incident angle, exposure time, rotation angle, etc. And we show incident angle calculation recipe for needed size of periodic patterns. We already manufacture PCs structure design and simulation tool. Nano structure of this paper’s result is applied to designed PCs patterns.

Nowadays, die attach film (DAF) gaining popularity in microelectronic packaging as integral part in facilitating the growth of wafer level packaging and stacked die packaging. DAF applied to the backside of wafers prior to saw have many advantages, such as the elimination of the epoxy dispensed process step and the reduction of epoxy related failure mode. However, the dicing process for DAF wafer usually associated with sidewall chipping, DAF whiskering and crack that will affect reliability of Quad Flat Non-Leaded (QFN) stacked die. Blade properties and characteristics are the crucial factor in analyzing the DAF dicing results. In this paper, we evaluate the blade characteristics before and after DAF wafer dicing process for our stacked die packaging. The qualitative measure by means of the Scanning Electron Microscope (SEM) and Energy Dispersive X-Ray (EDX) analysis were performed in order to understand the lamination and dulling effect on blade surface. The obtained results showed that sawing polymeric material such as wafer laminated with DAF induces lamination of polymeric material onto the blade surface and reduce blade cutting edge. As a result, reduce the quality of DAF dicing process.

In this paper, Saint-Venant end effects for plane deformations of transversely isotropic piezoelectric materials are investigated. The stress decay rates in linear piezoelectric strips that are traction free with two kinds of electrical boundary conditions are considered. The characteristic equations for decay rate are obtained for symmetric and antisymmetric deformations. Numerical values are given for the roots with the smallest positive real part, which are associated with the slowest decay. Saint-Venant end effects of piezoelectric materials of crystal class 6mm penetrate much further into strip than those of elastic isotropic materials.

In the paper, taking the particles suspension for filtered object, the effect of the long fiber bundles bulk density on filtration efficiency was studied through the filtration experiments with the designed experimental equipment. And combining with the filtering model of long fiber bundle filter to do fluid analysis, the result show that, for the filtering velocity is 72m / h, in the filtration efficiency, filtration cycle, backwashing and other aspects of comprehensive performance of long fiber high efficient filter are best when the packed density is 73kg/m3.

This paper aims to provide an understanding of the intrinsic frictional behaviour of CNTs under contact sliding by eliminating the possible effects of CNT rolling and slipping. Two critical steps towards the mechanism exploration were carried out: (1) the development of a new deposition method for CNT film fabrication, which allows the manufacture of densely packed, highly entangled CNT films to be firmly bonded on solid substrates for contact sliding testing; and (2) the theoretical understanding of the frictional behaviour of CNTs using the molecular dynamics analysis. The investigation clarified the controversial arguments in the literature and concluded that CNT films can be used as a superior solid lubricant with an ultra-low coefficient of friction of around 0.01.

This paper presents the effects of incorporating carbon nanotubes (CNT) into nylon 6 on thermal properties and fire performance of woven glass reinforced CNT/nylon 6 nanocomposite laminates. Incorporation of CNT in nylon 6 improved the thermal stabilities, thermal conductivity and fire performance of laminates without compromising their mechanical properties. The thermal conductivity of laminates with 2 wt% CNT increased up to 42% compared to that without CNT. The ignition time and peak HRR time was delayed approx. 31% and 118%, respectively, in laminates with 4 wt% CNT in nylon 6 over that without CNT.

This paper shows how the number of lap of spot welded joints in automotive steel sheets changes the life -cycle transform of itself. There has been significant developments in the life extension of automotive steel sheets, as well as in passenger safety. We verified the validity of the S-N curve of materials by QSTS test. Moreover, we used EZNCEN and HS40R, which are commonly used as automotive steel sheets because of their excellence in increasing fuel efficiency. The purpose of research was to compare the fatigue life of multi - lap of spot welded joints to there. In addition s, we used the two different kinds of sheets together in the same welding under the same condition. Through this whole process, the hypothesis on the life cycle of lethargy coefficients was found to be in good agreement with the result of the experiment. That is, when using sheets of the same materials in one welding, the fatigue life of two laps of a spot welded joint was found to be much superior by EZNCEN 5~14%, HS40R 17~30%,and when using each sheet of different materials, we found the decrease in fatigue life by 6~16%. Finally, the best value from the data was chosen based on the experiment for the analysis of the fatigue life of each layer.

In structural welded joints after long-term service under elevated temperature, fracture occurred mainly in the heat affected zone (HAZ). Recently, the nucleation and growth of creep voids in the fine-grained HAZ of weldments, recognized as Type IV fracture, has become an important problem for ferritic heat resisting steel. In this paper, a new computational model was presented to analyse the void growth induced creep damage development in HAZ. The new constitutive model based on continuum damage mechanics (CDM) equations is combined with a micromechanism-based model in order to account for the void growth process, which is different from the previous studies of creep damage. Material properties used for the creep damage computations are fitted from actual creep test data. Basic benchmark tests were performed to verify the new computational model. Then the model was used to study the creep damage development in the welded joints where four different material properties, base material, coarse-grained HAZ, fine-grained HAZ, and weld material, are taken into account. The numerical simulation results for creep lifetimes agreed well with the experimental results.

In this paper, the mechanical properties, such as the axial and radial Young’s moduli, shear moduli, buckling loads and natural frequencies, of single-walled carbon nanotubes, are estimated by a finite element approach. Each carbon nanotube is simulated as a frame-like structure and the primary bonds between two nearest-neighboring atoms are treated as isotropic beam members with a uniform circular cross-section. In the modeling work, the BEAM4 element in commercial code ANSYS is selected to simulate the carbon bonds and the atoms are nodes. As to the input parameters of the BEAM4 element, they are determined via the concept of energy equivalence between molecular dynamics and structural mechanics, and represented in terms of the force constants of the carbon bonds found in molecular mechanics. Based on this modeling concept, finite element models of both armchair and zigzag types of carbon nanotubes with different sizes are established and the mechanical properties of these tubes are then effectively predicted. Most of the computed results which can be compared with existing results show good agreement. Moreover, the effects of tube diameter, length etc., on the mechanical properties are also investigated.

This paper proposes a method based on vector calculation of flux density to evaluate the specific load capacity (SLC) of radial hybrid magnetic bearing (RHMB). The vector sum of the flux densities generated by the permanent magnet and the control current is calculated in this method, and then the functional expression of the SLC is built up via the flux densities. The influence of outer rotor diameter, fraction of circumferential rotor surface covered by poles and the length of the air gap are analyzed. It turns out that the SLC decreases with the maximum force of the bearing, and increases first and then decreases with the increase of pole area and length of the air gap. The maximum attainable SLC for RHMB of all sizes does not vary substantially from 23:1. The results of the analysis provide basis for the prediction of volume and mass for the RHMB in application.

On a global market, new products are subject to rising requirements regarding strength and quality. Simultaneously, the conservation of the environment and natural resources has become a key priority. One approach to these demands is the weight reduction of mechanical components by lightweight construction. The Transregional Collaborative Research Center (TR 10), funded by the German Research Foundation (DFG), is therefore working on the “Integration of forming, cutting and joining for the flexible production of lightweight space structures”. The use of light metals, like aluminium and composite materials is a main part in the TR10 process chain. This paper deals with the challenges of welding of light weight components made out of EN AW-6060. It shows the use and potentials of two innovative joining processes, particularly suited for welding aluminium. Especially developed for the fusion welding of aluminium components, BHLW (Bifocal Hybrid Laser Beam Welding), combines a Nd:YAG and a high power diode laser. The paper will give insight into the findings of the achieved results so far and line out the further proceedings with regard to critical parameters and their effect on the overall laser welding process. For the welding of aluminium composite materials, which play a big role in the TR10 process chain, Friction Stir Welding (FSW) is evaluated. As a solid state joining process, it can be used for the welding of materials that are hardly weldable with fusion welding techniques. In this paper, results of basic experiment for the joining of reinforced aluminium and the resulting process forces are presented.

In the field of light weight frame structures the assurance of dimensional accuracy and the prediction of structural properties especially during and after welding processes are of great importance. The problem in this regard mostly arises from the used welding technique which is characterised by complex interactions of various parameters. A simulative approach is useful in order to predict the structural behaviour and to improve the geometrical quality of joined light weight components after welding. As such, it contributes to reduce process adjustments in the early stage of the product life cycle, and therefore helps to save time and costs. In this paper an approach for modelling the innovative joining process of composite extruded profiles by friction stir welding is presented.

High-power optical multimode fibers are essential components for materials processing and surgery and can limit the reliability of expensive systems due to breakdown at the end faces. The breakdown threshold of fibers is determined by intrinsic materials properties and parameters of the technology applied. The aim of this paper is the identification of technological parameters that are crucial for the fiber quality. Fibers were drawn from preforms of Heraeus SWU with core material F300 and a low amount of OH-. Both, the cladding (fluorine doped SiO2) to core diameter ratio (CCDR) and the drawing speed were varied. CCDR values between 1.05 and 1.4 were used. Afterwards, the laser-induced damage thresholds (LIDT) of the fibers were determined. For comparison, also samples from preforms, which underwent different thermal treatments above the transition temperature, were tested with respect to their damage resistivity. Single and multi pulse LIDT measurements were done in accordance with the relevant ISO standards. Nd:YAG laser pulses with durations of 15 ns (1064 nm wavelength) and 8.5 ns (532 nm) at a repetition rate of 10 Hz were utilized. For the fibers, LIDT values (1-on-1, 1064 nm and 532 nm) increased with growing CCDR and with decreasing drawing velocities.

Green compacts of ceramics, glass ceramic composites and sinter glass ceramics contain different amounts of organic materials added as pressing aids or binders. Before sintering, these organics have to burn out completely. In oxidising atmospheres, the debindering process is mostly exothermic and therefore difficult to control. This uncontrolled heat production due to locally enhanced debindering and respective gas release may cause damages in the green compact microstructure. Therefore, debindering is usually operated with very low heating rates (< 3 K/min) which requires long processing times of many hours. In this paper, we will show that it is possible to reduce the processing time for debindering dramatically by using the decomposition rate of the organic binder, detected by the weight loss of the sample, as a control factor of the furnace.