Abstract: A finite element model of the double-wall acoustic insulation structure with a air layer and an acoustic absorbent layer made of the poroelastic materials is set up, the responses of this acoustic-vibration system are calculated by using of the direct finite element method when having a diffuse incident acoustic field acting on the incident surface, the radiant acoustic power from the another surface are achieved, then the Transmission Loss(TL) are formulated using the incident acoustic power and the radiant acoustic power. The effects of the thicknesses, elastic modulus, flow resistivity and viscous lengths of the poroelastic materials on TL are analyzed. The results show that the thicknesses and elastic modulus have a significant effects on TL, TL are enhanced with the thicknesses increasing of the poroelastic materials layers, a 4.9dB addition of TL is achieved when thickness is added from 2cm to 3cm; TL are enhanced with the reduction of the elastic modulus in considered frequency range, and TL are reduced with the declining of viscous lengths and with the addition of the flow resistivity when the frequencies are higher than 600Hz.
Abstract: The main objective of this study was to prepare bead milled-silica nanoparticles (SiO2) as reinforcing materials for transparent hard coating films. SiO2 dispersed in Dowanol PM without any stabilizer was used as a main component in the nanocomposite hard coating films to improve hardness of Poly methyl methacrylate (PMMA) sheets. However, the major challenge in hard coating formulation is the dispersion of nanoscale SiO2 particles. Bead milling machine (MiniCer, NETZSCH, Germany) equipped with different sizes of zirconia (ZrO2) beads (0.1, 0.5, and 1.0 mm) was used for dispersing 40wt% SiO2 in Dowanol PM to achieve target sizes of 200, 500, and 800 nm. The dispersed nanoparticles were characterized by UV-visible spectroscopy for their optical transmission, transmission electron microscopy (TEM) for particle morphologies, and dynamic light scattering technique (DLS) for the particles sizes. The milled-SiO2 nanoparticles were stable in Dowanol PM as suspensions with their particles sizes closed to the target sizes. The 200-nm suspension showed the longest storage time without any aggregate formation. Whereas, the dispersed nanoparticles suspensions with the particles size >500 nm formed agglomerates during storage. The SiO2/MTMS nanocomposite coating film was then prepared coated milled-SiO2 suspension in Dowanol PM on PMMA sheets. The film with 200 nm SiO2 showed the highest transparency (92% at 550 nm) which was like the uncoated PMMA sheets. At thickness of 3-microns, SiO2/MTMS nanocomposite films could improve pencil hardness of PMMA sheets from <H to 3H.
Abstract: Particleboard is an engineered wood product, factory-made from wood particles e.g. sawmill shavings, wood chips and saw dust and they are bonded into a solid board by appropriate binder. The scope of this paper is aimed to study the performance of particleboard made from sugarcane bagasse with the sodium silicate as the binder. The particleboards were produced by hot pressed at 150°C, 170°C and 190°C with the holding times of 20, 25 and 30 minutes respectively, at 10MPa. Different ratios of sodium silicate with reference to the bagasse by weigh i.e. 20%, 15% and 10% were added before the hot press process. The results obtained from the study shown that, the properties of the particleboard produced at the heating temperature of 170°C in 30 minutes with the addition of 20% of sodium silicate was the most promising. The densities, thickness swelling, flexural/bending strength and internal bond of the particleboards were tested based on the Japanese Industrial Standard (JIS), JIS A 5908:2003.
Abstract: Achieving energy efficiency of building in north part of Kazakhstan is very critical due to the large temperature difference during long harsh and severe winter and short hot summer seasons. Energy efficient building shows significant savings to homeowners including costs reduction from energy, water, waste, and lower operations and maintenance costs. In terms of building materials, lightweight aggregate concrete (LWAC) due to its thermal properties is often used to maintain thermal comfort levels in buildings and to reduce building energy consumption. In this paper, the potential of LWAC to improve the energy performance of building was assessed for LWAC with three different mixture proportions and a normal weight concrete (NWC) for comparison purpose. The energy saving effect of LWAC was simulated using OpenStudio software tools with an EnergyPlus engine. Moreover, annual heat loss and amount of heat transfer of construction wall of building were calculated. Results showed that LWAC can improve the energy efficiency of building and thus the use of LWAC can be a good alternative to the traditional NWC.
Abstract: Polyether ether ketone (PEEK), a thermoplastic polymer with remarkable mechanical properties apart from being bio-inert and approved by Food and Drug Administration-U S (FDA), is a promising bio-material at load bearing sites such as bone implants. The major challenge in PEEK associated bio composites is its process ability. Several ways have been attempted in past and finally resolved the issue by inkjet binder customized technique and Selective Laser Sintering for PEEK composite. An alternate method is presented in this work with ingenious process ability of PEEK, a polymer replacement for bone Collagen and Hydroxyapatites, the bone reinforcement prepared from egg shells. The alternate way suggested in this work is economically attractive without significant compromise in quality of the composite prepared.
Abstract: In this study Glass fibre reinforced fly ash -cement roofing tiles were fabricated using three different forms of coal fly ash (CFA) such as CFA as it is, CFA particle sizes below 75μm and below 45μm.The separated CFA was used to replace cement 30% by the weight and those matrices were reinforced by Alkali Resistant (AR) glass fibres adding 1% and 2% by weight.The corrugated roof tiles have dimensions of 490×250×8mm and they were hand cast using ordinary vibration. Physical and mechanical tests were performed after 28 days of aging. The tiles were tested in accordance with SLS 1189. Transverse strength increased with increasing fibre percentage. Further, the transverse strength decreased with decreasing CFA particle size. Highest characteristic transverse strength was observed in the CFA as it is sample which is 1650N and the lowest from CFA below 45µm particle size sample which is 1240N. However, all the samples satisfy the strength requirement which is 230N. High water absorption was observed in all the samples which is around 20%.The dry density was ranged in between 1.62-1.68g/cm3 .The lowest average dry density was observed in CFA as it is samples whereas CFA below 75μm particle size and CFA below 45μm particle size samples showed similar density values. The dry density of tile samples is in comparable with the dry density of asbestos cement sheets (≈1.63g/cm3) and the characteristic transverse strength is in comparable with Calicut clay tiles (1000-2000N) in Sri Lanka. Therefore, glass fibre reinforced fly ash-cement roofing tiles are promising substitute for asbestos roofing sheets.
Abstract: Bamboo fibers as a natural fiber offer numerous advantages such as high specific strength over synthetic fiber when used as reinforcing fiber for polymer composites. Yet the hydrophilic nature of bamboo fibers with high moisture absorption results in incompatibility in between bamboo fibers and unsaturated polyester resin. An experimental study was carried out to investigate the effects of alkali treatment of bamboo fiber on the mechanical properties and water sorption properties of polyester composite. The result revealed that, the bamboo fiber polyester composite with 5% Alkali treated bamboo fiber possesses the highest mechanical properties. Besides, Alkali treated fibers composite showed a significant reduction in moisture uptake compared to untreated fibers, where composite with 7% Alkali treated showed the lowest moisture uptake.
Abstract: Composite systems are materials that due to its characteristics and its achievement of synergistic effects are increasingly applied. The most frequent composites are composites mainly with long fibers. In the interaction with the polymer matrix can be used inorganic fibers, but recently there is a substitution of these fibers with organic fibers. The main advantage of using organic fibers is their low cost, low weight, and availability. The benefits can also cite environmental aspects. The disadvantage is the very nature of the organic material. The paper describes a long-fiber composite system prepared by vacuum infusion and compares the tensile strength of composites with randomly oriented and arranged sisal fibers, depending on the flow direction of the resin during vacuum infusion. Composite systems were cut from boards made by vacuum infusion using a water jet. These boards are widely used by industries such as automotive or building to where the natural fibers can create design function. The use of natural fibers in this process is inexpensive and such materials can be referenced as biocomposites, saving the primary raw material. The paper describes the tensile strength and hardness. Electron microscopy was used to evaluate fracture surfaces and the morphology of the fibers.
Abstract: The effective thermal conductivity (ETC) of the spherical packed-bed porous media in stagnant fluid case is estimated by modifying the color surface of the porous media as black surface. The Alumina-Cordierite (Al-Co) ceramic balls having average diameter (d) of 5.0 cm is constructed as the porous media and, then, a porosity (f) has 0.398. For development of the porous media as black surface, the Al-Co ceramic balls are painted by black color and then it is composed of 600 °C × 8 hr. The experimental procedure to evaluate the ECT is based on ASTM E1225. A higher temperature (TH) is investigated in the range of 400 to 800 K at the constant power of 350 W. The ETC of three surfaces of the Al-Co ceramics ball, i.e., original surface (λorg), combined black-painted and original surface (λcom) and black surface (λblk), are examined. From experiment, it is found that all ETC of three surfaces decrease with increasing TH. The value of three ETCs are in the range of 6.2 to 27.1 W/(m K). The lblk gives highest for the present research and, exactly, the worst case is obtained by λorg. Thus, the ETC of spherical packed-bed porous media with stagnant fluid can be improved by developing the color surface as black color.
Abstract: This study was aimed at finding appropriate levels of machine set up for small-sized rice milling machine in order to improve rice milling effectiveness. Small rice milling machines are used by farmers to reduce the reliance on commercial rice mill. However, they are found to produce greater quantities of broken rice grains than large-sized rice milling machine. This study investigated three factors of machine setup that would lead to smallest percentage of broken rice grains, i.e. size of hopper feed, gap adjuster, and outlet regulator. Each factor had three levels thus 3 x 3 factorial design was used to investigate the factors. It was found that all the three factors had significant impact on the number of broken grains. The optimum parameter settings that led to the smallest percentage of broken rice grains were as follows: size of hopper feed at 12 cm2, gap adjuster at 5 mm, and outlet regulator at 5 cm.