Aluminum Board Research Articles

Application of Damage Detection of Metal Structure Lamb Wave Modal Superposition Imaging Based on Scanning Laser Vibration Measurement

Metal structural plates are extensively used in various engineering structures due to their high strength, high-temperature resistance, toughness, and plasticity. However, they are susceptible to damage from external loads and impacts over time. The current Lamb wave detection methods suffer from dispersion and multimodal effects, leading to ineffective identification of damage information. In this paper, we investigate Lamb wave propagation in steel structure plates with flat-bottomed holes using a sinusoidal modulation five-peak wave signal. Finite element numerical models are developed, and an experimental platform is constructed using steel and aluminum boards. Experimental data is collected using a Scanning Laser Doppler Vibrometer (SLDV, PSV-500, Polytec Inc., Baden-Württemberg, German). The results demonstrate that, under the same frequency, the damage reflection energy for different modes is distinct. By fusing the data from the two modes, more accurate damage imaging results are obtained in the frequency-wavenumber (f-k) domain compared to single-mode imaging. Furthermore, experiments are conducted to locate damage in a steel board with a through hole and an aluminum plate with double flat-bottomed holes, confirming the feasibility of the proposed algorithm in isotropic plates.

Field Measurements for Traffic Noise Reduction in Highway Tunnels Using Closed-Cell Aluminum Foam Board

In order to explore the sound absorption and noise reduction performance of closed-cell aluminum foam in the tunnel, the field test of the sound absorption performance of aluminum foam board was carried out based on the installation of aluminum foam board in the whole line of Haoshanyu Tunnel on Qinglan Expressway. Combined with the existing loudspeaker test and typical tunnel measurements, a new field test method for the noise reduction performance of closed-cell aluminum foam board was proposed for two different working conditions including fixed-point pure tone sound source condition and mobile vehicle sound source condition. The testing results of the new methods were analyzed, and it showed that the closed-cell aluminum foam has good sound absorption property at the frequency spectra between 250 Hz and 1000 Hz, and the farther away from the sound source, the better the sound absorption effect. In the research on the noise reduction effect of actual vehicle, it was found that the insertion loss of the closed-cell foam aluminum board is about 4 dB(A), which indicated that the closed-cell aluminum foam can play a certain noise reduction effect in the tunnel.

Study on Combustion Characteristics of Ceiling Materials Using Cone Calorimeter

Urban living spaces with piloti structures are at high risk for deregulation of building protocols. Recent fire case investigation results have shown the path of the fire from the initial ignition point to the exterior material via combustible ceiling materials; thus, preventing the spread of the fire through the ceiling material is a priority. Accordingly, investigations were conducted on the ceiling materials used in piloti structures, and it was confirmed that SMC, aluminum, DMC, and gypsum board were the main components, with the SMC ceiling materials accounting for more than 70% of the composition. Cone calorimeter tests were performed on these ceiling materials, and the heat fluxes of SMC, aluminum, DMC, and gypsum board were determined to be 217.10, 15.07, 1.78, and 41.92 kW/m<sup>2</sup>, respectively.

MnO2/Al foil decorated air cleaner with self-driven property for the abatement of indoor formaldehyde

In this work, a self-driven indoor formaldehyde cleaner is designed by integrating α-MnO2 with exposed (3 1 0) crystal facet onto an electrothermal carbon membrane. The integrated device features bi-functions (air cleaning, and heating) and consists of four parts: painted board, the carbon membrane, the aluminum (Al) board, and the MnO2 decorated Al (Mn/Al) foil. The electrothermal carbon membrane can convert electrical energy into heat energy. At the maximum power of 846 W, the saturated temperature can be up to 97.1 °C and the heated MnO2 catalysts inhibit the accumulation of intermediates (formate and bicarbonate species) during formaldehyde abatement process. Furthermore, due to the temperature difference, the generated gradient force drives the movement of the gas and leads to the formation of four large recirculation zones in a simulated room, which facilitates the air disturbance. As a result, the concentration of formaldehyde in a chamber reduced from 1.24 to 0.13 mg/m3 in 90 min at operating temperature of 97.1 °C. More importantly, the contribution of temperature to mass transfer was comparable (only 11.9% less) to that of the fan disturbance reinforcement, which makes it possible to operate without additional fan assistance. This type of air cleaner by integrating MnO2 catalysts with heating equipment not only utilizes the residual heat to prolong the life span of active components but also provides a novel idea for the design of indoor formaldehyde cleaner.

Controlled TiO2 coating on hollow glass microspheres and their reflective thermal insulation properties

Hollow glass microspheres (HGMs) have great potential in building energy-saving and industrial insulation. Anatase TiO2-modified HGMs were prepared by a sol‒gel method in acetic acid-ethanol solution. Scanning electron microscopy, X-ray diffraction, zeta-potential measurements, nitrogen-sorption measurements, and Fourier-transform infrared and ultraviolet-visible-near-infrared diffuse reflectance spectroscopies showed that the alkali modification of the HGMs greatly influenced the loading and microstructure of the TiO2 film. The TiO2 loading could be accurately controlled by ethanol addition and the TiO2 coating time. A mechanism for the TiO2 coating of the HGM surface is proposed. The synergistic action of hydrogen bonding and electrostatic forces resulted in close contact between the HGMs and TiO2 sol at pH 3.5. The effects of different TiO2 loading rates on the reflective and thermal insulation properties were studied. The near-infrared reflectance of 15.9% TiO2 coated on HGMs was 96.27%, and the inner surface temperature of the composite pigment coated on aluminum board was reduced by 22.4°C. The TiO2/HGM composite pigments exhibited excellent solar reflective and thermal insulation properties, so have potential in the construction of exterior walls and roofs.

Flame retardant properties of oil palm trunk particleboard with addition of epoxy resin as a binder and aluminium hydroxide and magnesium hydroxide as additives

This research aimed at investigating the effect of epoxy resin and flame retardant additives on oil palm trunk particleboard. The oil palm trunk was used as a raw material with epoxy resin as a binder, which was synthesized by a reaction of epichlorohydrin and phenolphthalein, while aluminium hydroxide and magnesium hydroxide were used as flame retardant additives to manufacture particleboards. Four different types of particleboards were produced, control board, board with 10% epoxy resin, board with 10% epoxy resin and 6% aluminium hydroxide and board with 10% epoxy resin and 6% magnesium hydroxide, based on a target density of \(0.80~\hbox {g}~\hbox {cm}^{-3}\), at a temperature of \(180^{\circ }\hbox {C}\), a pressure of 5 MPa and a pressing time of 20 min. The mechanical, physical, functional group, spectroscopic, morphological and elemental analysis properties were determined in comparison with control particleboard. Thermal degradation and flame retardant analyses were also carried out to analyse the thermal properties of particleboards. The results indicated that particleboard bonded with epoxy resin and flame retardant additives had improved mechanical, physical, thermal and flame retardant properties compared to control oil palm trunk particleboard. Overall results showed that epoxy resin as a binder and aluminium hydroxide and magnesium hydroxide as additives have the potential to be incorporated into the particleboard to improve flame retardant properties.

Proposal of Innovative Flooring Options for Marine Containers

The paper outlines the innovative and progressive flooring options to build and equip marine containers. Several measurements, tests and simulations within this research study have been performed to find out whether it is possible to upgrade the marine container for general purposes with the polypropylene board with aluminum reinforcement. Research has confirmed that the aluminum board has a number of advantages. The main advantages include more than two times longer service lifespan compared to the conventional floors, absolute resistance to biological and chemical agents and simple floor repairs. Due to its durability, the aluminum board has a significant economic benefit for the user as well.

いくつかの建築材料の各種環境下での10 年間の暴露試験と結果

Wood, steel, aluminum, stainless steel, PVC board and cement mortar were exposed to outdoor, indoor and underground for 10 years to provide the relative comprehension for some building materials degradation. It was obtained that the progression degree of degradation differs depending on exposure place. For example, in the case of wood and steel, degradation in the underground is the most progress, and in the case of aluminum and PVC board, degradation at outdoor is the most progress. It is useful to understand intercomparison of building materials degradation.

ELEKTROKOAGULASI YELLOW-CGN DENGAN MENGGUNAKAN BAHAN YANG MUDAH DIDAPATKAN: PENGARUH WAKTU

The aim of this research to find the effect of time in electrocoagulation of yellow gcn. Electrocoagulation process use material that eazy to find and simple. Electrode in this research use aluminium from the waste of aluminium board industry around Sasirangan Industri and use carbon from battery. Current in Electrocoagulation processes use handphone. Result shown that effective time is used in electrocoagulation is 4 hours and 4 hours to wait yellow gcn coagulate.

Novel Bioreactor-System for <i>In Situ</i>-Cultivation of Artificial Tissue

A bioreactor is a device simulating physiological environments for different biotechnological applications. In highly promising research fields like tissue engineering micro-sized bioreactors were utilized successfully promoting mammalian cells to grow and build 3D cell structures similar to in vivo environments. For any practical application and even for improved R&D it is necessary to generate and maintain a physiological environment over the whole cultivation period (hours, days or weeks, in case of artificial organs even up to months). Depending on the field of application physiological environments can comprise different parameters. In case of mammalian cell lines these parameters require a complex supply and monitoring system. Thus, we developed a semi-automated bioreactor-system for long-term cultivation of different mammalian cell types imitating physiological conditions. The system included detection and control of the following parameters: temperature, pH-value, gas concentration and the continuous supply with nutrients. A micro fluidic network was established enabling a high through-put cultivating system as bioreactor-system. The bioreactor-system consists of several micro-sized chambers in a microliter scale (the related article discussing the micro-sized chambers “Miniaturized Flow-Through Bioreactor for Processing and Testing in Pharmacology” by Boehme et al is published within this issue). The chambers were placed in a polymeric slide each with an individual medium supply and disposal. Every single chamber thus was connected to an individual syringe-based micro-pump setup and supplied by nutrients solution with a velocity of 100μl/h. The pH-value was observed optically and controlled via CO2 supply. All gas interchanges into every single chamber were realized via semi permeable membranes. The required temperature was adjusted via an appropriate custom-fit heating system utilizing MOSFETs allocated on an aluminum board along the slides. Two slides each were housed in a PMMA case. This bioreactor-system is a first prototype for larger systems aiming for the parallel operation of up to 100 micro-sized reaction chambers.

大容量コンデンサを用いた電磁力インパルス音源の開発

The electromagnetic-force-powered impulsive sound source using large volumes of capacitors was developed. This source is composed of capacitors (44000μF), a coil and an aluminum vibration board (0.5 m x 0.5 m). Large magnetic power between the coil and the aluminum board is generated by discharging an electrical current from capacitors in a moment. This power moves the aluminum board in moment, and then, an impulsive sound is generated. This source could generate impulsive sounds with sound pressure over 60 Pa (= 130 dB) at a distance of 1 m from the source. The time width of generated sound was about 3 ms and the frequency range was from 5 to 500 Hz. This paper reports the overview of this device.

アルミニウムとポリイミド混在基板への選択めっき

回路基板上に実装する方法として電極パッドと基板を電気的に接続するワイヤボンディング法が利用されている。しかし近年の小型，軽量化を進める上でワイヤーのスペースが障害となっている。そこで新たな実装方法としてワイヤーを使わずに直接接続するフリップチップ法が注目されている。電極材料の多くはアルミニウムが使われており，一般的にアルミニウム上へのめっきにはジンケート法が用いられている。しかし，亜鉛置換浴は強アルカリ性，強酸性であるため，電極のエッチングロスやポリイミドへのダメージが懸念される。そこで，電極上へ無電解NiBめっきによりニッケルの微粒子を析出させ，続けて無電解NiPめっきで厚付けを行うことでジンケート処理を行わずにめっきを成膜した。その後，選択的なUV改質処理を行うことでポリイミド絶縁膜に対して配線を形成することが可能であった。

ガラス面結露対策のシミュレーション検討

Recently, there are a lot of buildings which have glass curtain walls from the design point of view. However, condensation often occurs on the spandrels of glass curtain walls in winter. The aim of this study is to establish measures to prevent condensation on the spandrels of glass curtain walls in commercial buildings. The authors' previous study shows the basic concepts to prevent condensation by conducting full-scale experiments for glass curtain walls (T. Gondo, 2011). However, in some cases there are differences between experiments and actual conditions in real buildings for example because of the influences of moisture evaporated from the calcium silicate board with high water content in the construction phase and the pressure difference between interior and exterior that occurs due to the temperature difference in winter. In this study, case studies are conducted using simulations to clarity the countermeasures to prevent condensation on the spandrels of glass curtain walls both in the construction and operational phases. The results of the study are summarized as follows. The conclusions from 1) to 4) are related to the operational phase and those from 5) to 9) are related to the construction phase. 1) In the standard condition, condensation occurs on the spandrels of glass curtain walls regardless of orientation and floor height. Especially, the amount of condensation is a lot for the cases for the north and with middle and high floor heights. 2) It is possible to reduce the amount of condensation by increasing the airtightness of the board, e.g., by installing joint gaskets and sealing tapes in the spandrels. However, condensation occurs on the glass of the spandrels due to the influence of moisture desorbed from and transmitted through the calcium silicate board. 3) It is possible to prevent condensation on the spandrel glass by increasing the airtightness by gaskets and exhausting the moisture from the calcium silicate board by the installation of 4 ventilation openings of 6mm x 60mm at both the upper and lower parts. 4) The installation of double glazing for the spandrel glass almost prevents condensation. However, condensation can still occur for the cases for the north and with high floor height. 5) In the cases under construction where the gaskets are installed for the board of the spandrel, condensation temporarily occurs due to the influence of moisture desorbed from the calcium silicate board regardless of orientation and floor height. 6) The amount of condensation tends to be large for the orientations where sunlight hits the board because the amount of desorbed moisture increases due to the heat of sunlight. In contrast, the amount of condensation is small for the north although condensation is generated for a long period. 7) It is possible to prevent condensation on the spandrel glass by exhausting the moisture from the calcium silicate board by the installation of 4 ventilation openings at both the upper and lower parts. The installation of the aluminum board, the calcium silicate board with low water content and double glazing are also effective. 8) The amount of condensation of the spandrel glasses is related to the insulation material behind the calcium silicate board and the paint color of the board. 9) Since condensation on the spandrel glass under construction is often temporary, it can be a countermeasure to wait until condensation disappears.

Measurement of internal defects in aluminum using a nano-granular in-gap magnetic sensor

Techniques for identifying defects in metals are very important in a wide variety of manufacturing areas. The present paper reports an eddy current testing method that employs a nano-granular in-gap magnetic sensor (GIGS) to detect internal defects in aluminum boards. The GIGS consists of a tunnel magnetoresistive film with nanometer sized grains and two yokes. In the presence of an external magnetic field, the nano-granular film exhibits only a small change in resistance due to the tunnel magnetoresistive effect. However, by placing it between two yokes, the magnetic flux can be greatly concentrated, thus increasing the change in resistance. The GIGS is a magnetic-field sensor that exploits this principle to achieve enhanced sensitivity. Moreover, because it has a cross-sectional yolk area of just 80 μm × 0.5 μm, it achieves outstanding spatial resolution. In the present study, it is used in combination with an eddy-current method in order to detect internal defects in aluminum. In this method, an excitation coil is used to apply an AC magnetic field perpendicular to the aluminum surface. This induces eddy currents in the metal, which in turn give rise to an AC magnetic field, which is then measured by the GIGS. The presence of defects in the aluminum distorts the eddy current flow, causing a change in the magnitude and distribution of the magnetic field. Such changes can be detected using the GIGS. In the present study, the proposed method was used to successfully detect indentations with diameters of 5 mm on the rear surface of an aluminum plate.

Computer simulation on temperature-dependent internal charging of complex dielectric structure

Some dielectric structures on satellites would experience temperature variation in a relatively large range, giving rise to a considerable change in its conductivity and consequently resulting in a significant influence on the dielectric internal charging. However, due to the limitation to the model of conductivity versus temperature and the tool for three-dimensional (3D) simulation of internal charging, this temperature dependence has not attracted much attention. Therefore, the conductivity of a satellite used modified polyimide is measured in a temperature changeable vacuum environment under high electric field (in MV/m). Keithley 6517 B is used to capture the mild electrical current in a relatively long measuring time (several hundred seconds). According to the Arrhenius temperature dependence and considering the conductivity enhancement due to high electric field, good agreement is obtained between fitted data and measured results by setting the activation energy to be 0.40 eV. In addition, the radiation induced conductivity (RIC) is taken into account by using the Fowler model. The conductivity at room temperature is found to be comparable to the RIC from the condition with 2 mm aluminum shielding. Using the derived results, the internal charging simulation in three dimensions is carried out for a selected part of a structure in this material, where Geant4 is used to derive the distribution of charge deposition and radiation dose in three dimensions. The incident energetic electrons are assumed to follow the exponential distribution under geosynchronous orbit severe radiation condition where the flux of electrons with energy larger than 2 MeV is assumed to be 1.0×109 m-2·-1·sr-1. It is found that the internal charging will become more serious as the temperature decreases. The charging time is about 1 h at temperature 330 K, whereas this time is increased to 10 h for temperature below 250 K. The most serious charging domain appears around the boundary line of the grounding surface close to the radiation source, where the electric field strength exceeds 107 V/m under the condition of 2 mm aluminum board with temperature 250 K. So the dielectric breakdown discharge is most likely to occur within this domain. Above all, under the condition of the material intrinsic conductivity (mainly depending on temperature) comparable to the radiation induced conductivity, temperature will play an important role in internal charging. This model for temperature-dependent conductivity and the method of 3D simulation of internal charging have great significance in both further evaluating spacecraft internal charging and implementing well protective designs.

광범위 시야 정보를 위한 UAV와 UGV의 협업 연구

본 논문은 기존의 UGV(Unmanned Ground Vehicle)에서 얻을 수 없었던 광범위한 시야를 얻기 위하여 UGV와 UAV(Unmanned Aerial Vehicle)를 함께 운용하는 플랫폼을 제안한다. UAV는 사용자 조종 없이 UGV 상단의 마커를 인식 한 후 UGV를 추적하며 광범위한 시야를 UGV 사용자에게 전달해 준다. UGV는 사용자가 직접 조정하며, 상단에 마커가 붙어 있는 넓은 알루미늄 판위에 UAV는 자동 이륙, 착륙 한다. UAV에는 2개의 카메라가 설치되어 있고, 하나는 마커인식을 위해 다른 하나는 전방의 광범위한 시야를 위하여 사용된다. UAV가 UGV를 추적하는데 있어 인식의 정확도를 높이기 위하여 마커 인식을 사용하였고, 전체 시스템의 통신은 WiFi 통신을 사용하였다. 실험의 결과를 통해 제안된 방법이 광범위 시야 정보를 얻기 위하여 UAV/UGV의 협업 연구에 효과적으로 적용될 수 있음을 보여준다. In this study, a cooperative UAV and UGV platform is proposed to obtain a wide range of visual information. The UAV recognizes a pattern marker on UGV and tracks the UGV without user control. It can provide wide range of visual information for a user in the UGV. The UGV by a user is controled equipped with an aluminum board. And the UAV can take off and land on the UGV. The UAV uses two cameras; one camera is used to recognize a pattern marker and another is used to provide a wide range of visual information to the UGV's user. It is guaranteed that the proposed visual-based approach detects and tracks the target marker on the UGV, and then lands well. The experimental results show that the proposed approach can effectively construct a cooperative UAV/UGV platform for obtaining a wide range of vision information.

Fluxless bonding of Si chips to aluminum boards using electroplated Sn solder

The high thermal conductivity and light weight properties of aluminum (Al) make it a promising material in high power device packaging and automotive electronics. A primary challenge is its high coefficient of thermal expansion (CTE) of 23 ppm/°C. In this research, we investigated the possibility of surmounting this challenge by bonding large Si chips to Al substrates using fluxless tin (Sn) solder. The Si–Al pair probably has the largest CTE mismatch among all bonded structures in electronic packaging. In experiments, 0.1 μm Cr layer and 0.2 μm Cu layer were deposited on Al substrates, followed by an electroplated 25 μm copper (Cu) layer. The Sn solder layer was then electroplated over the Cu, followed immediately by thin (0.1 μm) silver (Ag) layer. The joint thickness was controlled either by bonding pressure or by incorporating Cu spacers. Microstructure and composition of the joints were studied with scanning electron microscopy and energy dispersive X-ray spectroscopy. Despite the large CTE mismatch, the bonded structures did not break. The minimum fracture force measured among six samples by shear test is higher than three times of what specified in MIL-STD-883H, method 2019.8. This preliminary result corroborates potential adaption of Al substrates and boards in electronic packaging where lightweight is essential.

A novel COB structure with integrated multifunction

A novel COB (chip-on-board) structure with integrated multifunction is presented. The structure is prepared by laminating copper plate with FR4 board and then coating with a silver layer to offer high reflectivity and high conductivity. In comparison with MCPCB (aluminum) and ceramics (Al2O3) board, the substrate brings about 10% higher light extracting efficiency than aluminum board and 5% higher flux maintenance ratio than ceramics (Al2O3) board at 3000 h. With integrated multifunction, through an IC component driving high voltage serial LED chips, the COB can be directly connected to AC 110 V or 220 V power supply in lighting application.

Process and Interface Bonding Mechanism of Alumina Reinforced Aluminum Matrix Composite Board by Sandwich Rolling

A new type of composite board containing micro-arc oxidation ceramic particles is successfully prepared by sandwich rolling, opening up a new way for preparing metal-matrix composites. By tearing test, it is shown that the aluminum board pretreatment, rolling temperature and reduction ratio are important effect factors on the bonding strength of the composite board, and a maximum bonding strength appeared within the test temperature range. It is known by temperature factor research that three inferior level mechanisms, the reversion-recrystallization softening, metal atomic energy rising and oxidation layer related to fissure and mosaic mechanisms exist in the present experimental conditions, and their dominant role positions are affected by the temperature factor. During the rolling process, the ceramic particles from the fragmentized micro-arc oxidation layer on aluminum alloy surface led to the formation of a mosaic combination relationship between the double plates.

Experimental Research on the High Speed Drilling of PCB Using Microdrill

Printed circuit board (PCB) composed of glass fiber reinforcement plastic and copper foil is a kind of typical composite material. The cutting process of fiber reinforcement plastic materials such as carbon fiber or glass fiber reinforcement plastic materials have been studied for many years, but the drilling process of printed circuit board using microdrill is more complicated than common carbon fiber reinforcement plastic materials. It is event that the cutting force changed when drill different material. The variation of drilling force may cause some problems such as drill break, board delamination. So it is important to study the drilling force in PCB drilling. The precision dy-namometer was used in experiments and cutting process was analyzed in this paper. The drilling process of PCB experience six stages and the drill will meet aluminum board, glass fiber reinforce-ment plastic (GFRP) and base strip. According to the drilling force in one circle, the peak force ap-peared at the moment of drilling copper foil and another smaller peak force appeared at the moment of drilling aluminum board and base board. The experiment results show that thrust force increased with federate and decreased with rotational speed.