Aluminum Block Research Articles

Assessment of Areal (Three-Dimensional) Roughness Parameters of Milled Surface Using Charge-Coupled Device Flatbed Scanner and Image Processing

A new application of the charge-coupled device (CCD) flatbed scanner for the noncontact assessment of areal three-dimensional (3D) roughness parameters of milled surfaces is proposed in this work. The surfaces were prepared by milling a block of aluminum at five different feed rates using a CNC milling cutter. The specimen was placed on the flatbed scanner with the milled surface facing the scanner array. The scanned images were analyzed using image processing to extract the average pixel intensity, root-mean-square pixel intensity, variance, black-to-white ratio, and bright region average area intensity within a region-of-interest. These parameters were correlated with the 3D areal parameters obtained using a state-of-the-art focus variation 3D metrology system. The highest correlation of 0.9931 was obtained between the average pixel intensity from the scanned image and average areal roughness Sa at a scanning height of 7.2 mm from the scanner surface. Compared with the costly 3D metrology system, the flatbed scanner combined with the proposed image processing algorithm has significant potential for roughness assessment due to the high correlation between the image parameters and roughness parameters.

Strength analysis of aluminium foil parts made by composite metal foil manufacturing

A number of different parts for mechanical testing were produced using composite metal foil manufacturing (CMFM). This process is a combination of laminated object manufacturing and brazing technology. Aluminium is one of the toughest metals to join and CMFM can achieve this task with ease. By using aluminium 1050 foils of 0.1 mm thickness, various parts were made according to British and International Standards, including lap joints, peel specimens, dog-bone specimens and tested for their mechanical properties. A special, 80 % zinc and 20 % aluminium by weight, brazing paste was utilized for joining the foils together. The test of the single lap joints show that none of the specimens failed at the bonded area and the failure was always due to fracture of the parent metal. Cohesive failure was also observed for the single lap joints by using 10 mm thick aluminium metal plates. It helped in calculating the lap shear strength which is a useful design parameter. The peel test showed good bond consistency in all the specimens with an average peel strength of 20 MPa. Comparative tensile test was conducted with a dog-bone specimen machined from a solid block of aluminium 1050 and specimens made with CMFM. The results showed that the specimens made by CMFM fracture at force values that are higher than that of the parent metal. This demonstrates that CMFM has the capability to produce high quality and stronger parts as compared to conventional machining methods employed for the production of metal parts. The effect of using different number of layers for the same cross-sectional area has also been investigated.

A Comparison of the Efficacy of a Primerless Orthodontic Bonding Adhesive as Compared to Conventional Materials: an Invitro Study

Abstract Introduction: Light cured composite resins have become the method of choice in orthodontic bonding procedures worldwide. In recent years, a new primerless orthodontic bonding composite, Heloisit with good bond strength, fluoride release and an advantage of not requiring use of a primer has been introduced. Aims: To compare the bonding characteristics of commonly available self and light cured adhesives with primerless system. Materials and Methods: One hundred twenty extracted human premolar teeth were mounted on similar sized aluminium blocks and were divided into four groups of thirty teeth each. All teeth were bonded with four different bonding systems Group i) Light Cured Primerless orthodontic Composite (Heliosit®, Ivoclar Vivadent, Schaan, Liechtenstein), Group ii) Light Cured Composite Resin (Transbond XT®, 3M Unitek), Group iii) Light Cured GIC (GC Fuji Ortho LC®, GC Corp.), Group iv) Self Cured Composite Resin (Rely-A-Bond®, Reliance, Inc., Illinois, USA) using metallic premolar first premolar brackets (0.022” Ortho Organizers). These were evaluated for shear bond strength using an Instron testing machine. Surface characteristics after debonding were studied under scanning electron microscopy (SEM) and evaluated using the adhesive remnant index (AR Index). Results: Shear bond strength (SBS) of primerless orthodontic light cured Heliosit® composite was clinically significant and adequate for clinical use. It lies intermediate to Transbond XT light-cured composite and Light Cured GIC. The least bond strength was shown by Rely-a-Bond® self-cured composite resin. Conclusions: Heliosit® light cured primerless orthodontic composite can be used for everyday clinical use due to its ideal characteristics of sufficient bond strength and reduced chances of enamel damage at debonding. Additionally, it is primerless and saves valuable clinical time.

밀폐된 공간 내 공랭식 PEMFC의 자연대류 열전달에 대한 실험적 연구

This study presents an experiment investigation on natural convection heat transfer of air-cooling Proton exchange membrane fuel cells (PEMFCs) in a enclosure system for unmanned aerial vehicles (UAVs). Considered are replacing fuel cell stack with Aluminum block for heat generating inside a enclosure chamber. The volume ratio of fuel cell stack and chamber for simulation to the actual size of aerial vehicle is 1 to 15. The parameters considered for experimental study are the environmental temperature range from <TEX>$25^{\circ}C$</TEX> to <TEX>$-60^{\circ}C$</TEX> and the block heat input of 10 W, 20 W and 30 W. Effect of the thermal conductivity of the block and power level on heat transfer in the chamber are investigated. Experimental results illustrate the temperature rise at various locations inside the chamber as dependent upon heat input of fuel cell stack and environmental temperature. From the results, dimensionless correlation in natural convection was proposed with Nusselt number and Rayleigh number for designing air-cooling PEMFC powered high altitude long endurance (HALE) UAV.

SMA를 이용한 공구홀더의 자동공구교환장치 개발

Micromanufacturing is a useful system for reducing energy consumption. For micromanufacturing, tool clamping and workpiece clamping are important components to realize the machining process. Therefore, a shape memory alloy (SMA) ring type tool holder is developed. In addition, this holder needs cooling and heating processes to execute the tool clamping process. This study suggests a cooling/heating device based on peltier elements. The device will be applied to the heating/cooling process of an automatic tool changer (ATC) for the SMA tool holder. This study introduces the configuration and operating principle of the proposed ATC system. The description and prototype evaluation of this system were given. Plastic bolt and aluminum block were selected to enhance the cooling performance, and the installed tool was changed in 17 s during the experiments.

Neutronic analysis of a U–Mo–Al fuel and europium as burnable poison

This work presents the neutronic analysis of the U–Mo–Al dispersion fuel concerning uranium density increase and shows comparisons relatively to the U3Si2–Al fuel. The U3Si2–Al uranium density varied from 3.0 to 5.5gU/cm3 while that of U–Mo–Al fuel varied from 4.0 to 7.5gU/cm3. The molybdenum mass content in the former case varies from 7% to 10% in mass. Here, it is also proposed the utilization of burnable poison nuclides in the U–Mo–Al fuel meat. Since the fuel is metallic, gadolinium and europium were chosen as candidates to cope with this task. A recently developed cell code at IPEN (HRC) composed of the coupling of the codes HAMMER-TECHNION for the cell analysis, ROLAIDS for the actinide self-shielding calculations and CINDER-2 for the actinide and fission transmutation was employed for the neutronic analyses of U–Mo–Al. The simulated reactor core was similar to the one of RMB (Brazilian Multipurpose Reactor) composed of an array of 5×5 positions with 23 fuel elements and 2 aluminum blocks. A second analysis of the europium case employed the SERPENT code in an explicit core modeling. The burnup calculations were performed considering a power of 30MW during three cycles of RMB and 30days. The analyses revealed that the molybdenum content has a great impact in the core reactivity due to its high absorption cross section. A value of 7% was found adequate for the molybdenum mass content. The analyses also reveal that europium is a better burnable poison than gadolinium for the core cycle length and power level under consideration. However, for the U–Mo–Al case, k∞ increases up to a maximum value and decreases afterwards. This is a striking result since the reactivity for the U–Mo–Al fuel does not increase steadily as verified for the U3Si2–Al case. Beyond a certain uranium density, the reactivity will decrease making useless the addition of more uranium.

Preparation of Nano Aluminium Powder (NAP) using a Thermal Plasma: Process Development and Characterization

A bottom up approach for the preparation of Nano Aluminium Powder (NAP) using a Transferred Arc Thermal Plasma Reactor (TAPR) is described. The aluminium block is subjected to evaporation by the application of a thermal plasma. The aluminium vapour produced is rapidly quenched to room temperature resulting in crystallization of the aluminium vapour in nano-particulate form. Various process parameters, such as the plasma torch power, reactor pressure and plasma gas composition were optimized. This paper also describes the characterization of NAP by analytical methods, for the estimation of the Active Aluminium Content (AAC), Total Aluminium Content (TAC), XRD, bulk density, BET surface area, HR-TEM etc. The results are compared with those for samples prepared in other thermal plasma reactors, such as the DC Arc Plasma Reactor (DCAPR) and the RF Induction Thermal Plasma Reactor (RFITPR), and for commercially available NAP samples (ALEX, prepared by the EEW technique).

Fibrous Tectonics: A Rethinking of Composite Production through Innovation and Exploration of Molding Techniques and Methodologies

The inherent possibilities of composites present an exciting frontier in architecture that has remained largely untapped. In light of the current computational capacities and new digital tools in manufacturing, composites are just beginning to re-situate themselves in the field of architecture. Efficiency and durability coupled with a load bearing capacity make a strong case for the use of composites as a primary building material.We now possess the computational and digital manufacturing tools that make the development of a composite building viable. On a holistic level, the research has concerned itself with an overarching focus on developing a composite building which minimizes the required costs and labor while simultaneously creating the potential for customized forms. Based on the concepts of mass customization, when the workflow from digital conception to digital production is seamless, a variety of composite structures can be produced at no greater expense. This potential for an efficient “one off” composite architecture empowered by digital manufacturing and computation, is where the research is positioned.At present, the research has been focused on exploring surface composite structures through a reinvention of the ‘mold’. This approach has involved using inflated bladders, rather than traditional molds of milled foam or aluminum in order to produce composite structures. In doing so, the benefits of inflatables are all encompassing. Not only do they allow for inexpensive transportation and rapid deployment, but they also lend themselves to the production of large scale structures through the simple use of air and pressure, thus minimizing both material and effort. This lies in stark contrast to traditional composite manufacturing techniques which require molds to be milled out of solid aluminum blocks or high density foam volumes, whereas inflatable molds are easily heat sealed and inflated. When considering issues of scalability, traditional molding techniques demand significantly more labor, material, and with that, overarching costs. Inflatable molds however, require only more air.Coupled with the rethinking of molding techniques is a consideration in the technological methodologies in order to produce such composite structures. The research looks to the new developments in the composite industry, such as Resin Transfer Molding (RTM) and Vacuum Assisted Resin Transfer Molding (VARTM). These processes greatly simplify the manufacturing of composites and eliminate much of the manual labor traditionally associated with composite structures. By taking advantage of the existing vacuum bag used for compaction while producing composites, the VARTM process pulls resin through the bag under vacuum pressure, thus wetting out the fibers and eliminating typical layup deficiencies while producing a nearly weightless composite structure.

放電焼結法により作製したTiB&lt;sub&gt;2&lt;/sub&gt;／アルミニウム複合材料の熱的、機械的特性

By optimize the mixing conditions of powders and the conditions of the spark plasma sintering, dense 20 vol % TiB2 particle aluminum composites with uniform distribution of particles were obtained. The thermal conductivity and the mechanical properties were estimated. The experimental results were good agreement with the theoretical value based on the rule of mixture which is considering the uniform distribution of particles and without pores. The strength of the composites at room temperature is lower than that of pure aluminum block, but the strength of the composites was improved at higher temperature such as at 100°C compared with the monolithic aluminum.

Interaction between Macrophages and Fibroblasts during Wound Healing of Burn Injuries in Rats.

Analysis of the structural changes and cell-to-cell interactions occurring during wound healing of burn injuries is essential to elucidate the morphological characteristics of the reconstitution of tissue architecture. However, conventional approaches do not provide sufficient information with respect to cell-to-cell interactions during wound healing. The aim of this study was to evaluate the interaction between bone marrow-derived cells and resident stromal cells throughout the wound healing of burn injuries, using immunohistochemistry and focused ion beam/scanning electron microscope tomography. We induced third-degree burn injuries on the backs of Wistar rats with a heated cylindrical aluminum block (2.0 cm in diameter). At 7 and 14 days after the burn injuries, the burned skin was immunostained with anti-Iba1 and anti-HSP47 antibodies for visualization of bone marrow-derived cells/macrophages and resident stromal cells/fibroblasts, respectively. Normal skin tissue was used as a control. Double-staining immunohistochemistry revealed frequent contacts between macrophages and fibroblasts and a higher contact ratio in the 3 normal skin compared with burned skin, particularly in the areas of granuloma. Three-dimensional ultrastructural analysis with focused ion beam/scanning electron microscope tomography revealed that macrophages and fibroblasts were located closer together in the normal skin than in the burned skin, confirming the analysis by light microscopic observations and ultrastructural analysis from single sections. These results highlight the importance of contact between macrophages and fibroblasts in the maintenance of skin tissue structure and during wound healing.

Evaluation of Linear Dimensional changes of Investment Material when Various Combinations of Dental Plaster and Dental Stone are used as an Investment Material

ABSTRACT Aims To evaluate dimensional stability when various combinations of dental plaster and dental stone are used as an investment material. Context Dental plaster is routinely used as an investing material to acrylize dentures with some acceptable linear dimensional changes in the finished acrylic denture. This study aimed to evaluate which combination of dental plaster and dental stone, when used as an investment, will produce fewer linear dimensional changes in acrylic dentures. Materials and methods An aluminum block is prepared with sharp margins. The block is invested with various combinations of dental plaster and dental stone. The linear dimensional changes are measured using a digital caliper. Statistical analysis The results obtained were subjected to statistical analysis using analysis of variance test. Results Investing with 100% dental stone and a combination of 70% dental stone and 30% dental plaster showed fewer dimensional changes. Conclusion A combination containing higher percentage of dental stone may be used for investing to produce a finished denture with fewer linear dimensional changes. How to cite this article Kumararama SS, Chowdhary R. Evaluation of Linear Dimensional changes of Investment Material when Various Combinations of Dental Plaster and Dental Stone are used as an Investment Material. Int J Prosthodont Restor Dent 2016;6(1):1-5.

Establishment of Shaped Charge Optimum Parameters for Small Scale Hydrodynamic Penetration

An investigation is intended to establish suitable parameters for a simple shaped charge mechanism (SCM) assembly that can be utilized for small scale hydrodynamics penetration test. Some basic features of the SCM parameters were based on previous researchers’ findings. Three sets of tests were conducted to verify parameters such as cone liner angle and thickness, material of charge (explosive) casing and standoff distance (SoD). Single and welded stacks of mild steel plates and Aluminium blocks were used as targets. Two type of explosive were used, military grade plastic explosive (PE) or C4 and a commercial grade explosive, Emulex 700. A simple but effective compressing mechanism was developed to eliminate air pockets and maximised the explosive density. The SCM parameters were improved through series of tests and results have shown that hydrodynamic penetrations have taken place in every test conducted. Suitable small scale SCM parameters were successfully established which can be utilized for future study on hydrodynamics penetration.

Multiphysics modeling and characterization of explosively loaded aluminum blocks

A coupled Eulerian–Lagrangian finite element simulation is made of an aluminum block of dimensions 4 × 2 × 1/2 in (101.6 × 50.8 × 12.7 mm) subjected to an intensive shock load at its top. The shock load was introduced by the detonation of plastic explosives which were attached to the top of the block. The objective is to determine the effect of the shock on the deformation history of the metallic block accounting for strain rate effects. The dynamic response of the block to the high-pressure pulse was simulated by taking into account the resulting elasto-plastic deformation, the solid–fluid interaction and the adiabatic temperature rise. The dynamics of the transient stresses below the loaded surface was captured by our model. Three aspects of the explosive shock load were accordingly examined: (i) the explosive thickness and (ii) the explosive overhang length and thickness upon the resulting deformation pattern. Upon the complete dissipation of the shock, we were able to determine the distribution of the residual stress in the principal directions. Compressive residual stresses were observed in the region at and below the surface of the loaded end. The above predictions were experimentally validated using explosively loaded aluminum blocks. The experimental findings revealed general agreement with the finite element predictions of both the deformation pattern and the residual stresses.

Advances in Ultrasonic Imaging for Internal Flaws in Structures

&#x0D; &#x0D; &#x0D; In the field of non-destructive testing of structures, 3D imag- ing of internal flaws is a critical task. Defect imaging allows the engineer to make informed follow-up decisions based on the morphology of the flaw.&#x0D; This paper will present advances in ultrasonic tomography for the 3D visualization of internal flaws in solids. In particular, improvements to the conventional tomographic imaging algorithms have been made by utilizing a mode-selective im- age reconstruction scheme that exploits the specific displacement field, respectively, of the longitudinal wave modes and the shear wave modes, both propagating simultaneously in the test volume. The specific mode structure is exploited by an adaptive weight assignment to the ultrasonic tomographic array. Such adaptive weighting forces the imaging array to look at a specific scan direction and better focus the imaging onto the actual flaw (ultrasound reflector).&#x0D; This study shows that the adaptive weighing based on mode structure improves image contrast and resolution compared to a conventional ultrasonic imaging technique based on delay- and-sum. Results will be shown from simulations and imaging experiments of simulated flaws in an aluminum block.&#x0D; &#x0D; &#x0D;

Influence of Orientation and Radiative Heat Transfer on Aluminum Foams in Buoyancy-Induced Convection.

Two differently-produced open-cell aluminum foams were compared to a commercially available finned heat sink. Further, an aluminum plate and block were tested as a reference. All heat sinks have the same base plate dimensions of four by six inches. The first foam was made by investment casting of a polyurethane preform and has a porosity of 0.946 and a pore density of 10 pores per linear inch. The second foam is manufactured by casting over a solvable core and has a porosity of 0.85 and a pore density of 2.5 pores per linear inch. The effects of orientation and radiative heat transfer are experimentally investigated. The heat sinks are tested in a vertical and horizontal orientation. The effect of radiative heat transfer is investigated by comparing a painted/anodized heat sink with an untreated one. The heat flux through the heat sink for a certain temperature difference between the environment and the heat sink’s base plate is used as the performance indicator. For temperature differences larger than 30 C, the finned heat sink outperforms the in-house-made aluminum foam heat sink on average by 17%. Furthermore, the in-house-made aluminum foam dissipates on average 12% less heat than the other aluminum foam for a temperature difference larger than 40 C. By painting/anodizing the heat sinks, the heat transfer rate increased on average by 10% to 50%. Finally, the thermal performance of the horizontal in-house-made aluminum foam heat sink is up to 18% larger than the one of the vertical aluminum foam heat sink.

ICONVERT: an integrated device for the UV-assisted determination of H2S via mid-infrared gas sensors.

In this technical note, we describe an integrated device platform for performing in-flow gaseous conversion reactions based on ultraviolet (UV) irradiation. The system combines, using the same footprint, an integrated UV-conversion device (iCONVERT), a preconcentrator unit (iPRECON), and a new generation of mid-infrared (MIR) gas cell simultaneously serving as a photon conduit, i.e., so-called substrate-integrated hollow waveguide (iHWG) optically coupled to a compact Fourier transform-infrared (FT-IR) spectrometer. The iCONVERT is assembled from two blocks of aluminum (dimensions, 75 mm × 50 mm × 40 mm; L × W × D) containing 4 miniaturized UV-lamps (47mm × 6 mm × 47 mm each). For the present study, the iPRECON-iCONVERT-iHWG sensing platform has specifically been tailored to the determination of H2S in gaseous samples. Thereby, the quantitative UV-assisted conversion of the rather weak IR-absorber H2S into the more pronouncedly responding SO2 is used for hydrogen sulfide detection. A linear calibration model was established in the range of 7.5 to 100 ppmv achieving a limit of detection at 1.5 ppmv using 10 min of sample preconcentration (onto Molecular Sieve 5A) at a flow rate of 200 mL min(-1). When compared to a conventional UV-conversion system, the iCONVERT revealed similar performance. Considering the potential for system miniaturization using, e.g., dedicated quantum cascade lasers (QCL) in lieu of the FT-IR spectrometer, the developed sensing platform may be further evolved into a hand-held device.

Multicomponent reduced scale seismic modelling: upgrade of the MUSC laboratory with application to polarization observations

Reduced scale physical modelling is a useful intermediate step to fill the gap between field measurements and numerical simulations. In many different areas of seismology, multicomponent measurements are now commonly recorded and processed. However, up to now, laboratory facilities providing flexible and accurate reproduction of large multicomponent seismic experiments have not reached maturity. Within this context, we present an improvement of a measurement facility (MUSC) developed previously to enable the flexible and versatile reproduction of seismic experiments at reduced scale. This new measurement system provides simultaneous measurements of the vertical and the horizontal components of seismic wavefields by taking advantage of recent developments in laser ultrasonic sensing technologies. Reference measurements on an aluminum block are carried out in order to quantitatively evaluate multicomponent measurements. Noise characterization, surface wave ellipticity analysis and waveform comparisons with a semi-analytical model are presented. To enable the simultaneous comparison of phase and polarization attributes, we also introduce a regularized version of the polarization attributes and apply it to synthetic and experimental data. These comparisons demonstrate that high fidelity multicomponent reduced scale physical modelling is possible with this new facility. An illustrative example with a model containing a shallow cavity is presented. In this case, multicomponent measurements help to identify the cavity signature but multiples have a detrimental effect on regularized instantaneous polarization attributes. By assessing the reliability of the MUSC measurement facility in the performance of massive high-quality multicomponent data acquisition at the laboratory scale, this study highlights the interesting potentials of reduced scale modelling of seismic wave propagation for a large variety of applications

Development of an advanced external fixation device for rat femur defect

The Regeneration of bone defect is a major challenge in modern tissue engineering and regenerative medicine and its appropriate animal model is needed to translate research finding into clinical application. Animal long bone defect model requires a special bone fixation device which has verified mechanical stability and reproducibility. This study was more focused on developing a stable external fixator when working with bone defect model in rats. Further studies using larger animal experimental groups are necessary to explore reproducibility. The external fixation devices were composed of one aluminum block and four pins. The pins were made of various types (material: titanium, stainless steel; thickness: 1.2, 1.3, 1.4 mm; pitch: 0.5, 0.3 mm). For the evaluation of mechanical stability difference due to various types of the pins, we did two sets of mechanical measurements (mean axial stiffness) of the external fixators using blocks and excised rat femurs, and in vivo performance over a 6-week period. Under 8 mm offset, 1.2 mm thickness titanium pins were appropriate for rat femur defect model when pitch decreased from 0.5 mm to 0.3 mm. In addition, we can observe the pitch of the pin have a decisive effect on mechanical stability of the external fixator and expect this finding to be contributive to the related future research.

Performance Analysis of a New Water-based Microcooling System

In the electronic industry, dissipating the heat load becomes a critical factor for highly developed designs. These require higher power transfer in a more compact size. In the current study, a new microcooling system was developed and tested. It utilizes the enhancement in heat transfer characteristics associated with implementing a vortex promoter in the evaporator segment of a water-based heat pipe. The test evaporator was a cavity of 4-mm diameter and 23-mm length in an electrically heated aluminum block. A helical coil (of various diameters, namely 500, 300, and 250 μm) was introduced to the evaporator segment to act as a vortex promoter. Configurations of a new microcooling system based on a modified heat pipe technology were built and tested. The presented system proves to work efficiently in situations where a closed-loop thermosyphon encounters film boiling limitation. The most efficient configuration has a flow modifier diameter about one-tenth of the evaporator chamber gap, while the diameter of the return line was three-quarters of the evaporator gap. This configuration shows a stable operation characteristic and possesses high thermal efficiency. The maximum heat flux obtained by such a configuration was 305 W/cm2 when it runs at 103°C saturated temperature and 0.01°C/W thermal resistance. A uniform temperature distribution along the system was noticed.

Energy Transfer During Freeze-Drying in Dual-Chamber Cartridges

Freeze-drying essentially requires knowledge about the heat and mass transfer characteristics to assure product quality. Whereas this understanding has been created for freeze-drying in vials, only limited information is available for state-of-the-art multiple compartment container systems such as dual-chamber cartridges (DCCs). Therefore, the aim of this study was to investigate the heat transfer characteristics of this novel container format. Sublimation tests were carried out using pure water at 60, 100, 150, and 200 mTorr chamber pressure at a shelf temperature of 0°C. Custom-made aluminum blocks were used as holder systems. Two heat transfer coefficients could be identified: the coefficient characterizing heat transfer between shelf and block, KAl , and between block and cartridge, KDCC . KAl was dependent on all three modes of heat transfer: contact conduction, gas conduction, and radiation. For KDCC , contact conduction was negligible. Radiation strongly influenced the overall energy transfer as it is the major mode of heat transfer for KDCC and contributes up to 44% to KAl . A third coefficient, Ktot , was defined as an overall heat transfer coefficient. This knowledge about heat transfer enables a purposeful development and control of optimized lyophilization processes for this novel container system.