Perpendicular Grain Research Articles

Experimental investigation and analytical model of traditional Kath-Kuni Wooden joints

ABSTRACT The traditional Kath-Kuni construction system is considered an earthquake-resistant construction system. Its major earthquake-resistant features are its wooden connections, such as Maanwi (dovetail), Kadil (dowel), and friction capacity between layers. Hence, in the present research, experiments have been done to understand the behaviour and failure mechanism of these wooden joints, and their moment-carrying capacities have been calculated. In experimental studies, varying sizes of members and connection keys for Maanwi, Kadil, and different materials for friction coefficient have been considered. Analytical equations for various failure mechanisms have been proposed to understand the behaviour, failure mechanism and capacities, analytically, and the results are compared with the experimental data. Brittle failure was observed for both the Maanwi and Kadil connections. The capacity of the Maanwi connection was governed by the area available to resist the rotation and wood tensile capacity in the perpendicular grain direction. The Kadil connection capacity depends upon the Kadil key's size and the wood's capacity in tension and torsion-induced shear in the perpendicular grain direction. The friction coefficient was found to vary from 0.45 to 0.80 between different surfaces under constant overburden.

Mechanical properties and failure mechanisms of engineering bamboo scrimber

This study aims to systematically investigate the mechanical properties of bamboo scrimber (BS) along three main loading directions. Through tensile, compression, and shear tests, the mechanical properties of BS were obtained and compared with those of other engineering timber or bamboo products. The results illustrated that the mechanical properties of the BS were affected by the loading direction, and the mechanical properties of the BS along the parallel grain direction were better than those of the BS along the other two perpendicular grain directions. In addition, the results from the comparison between the BS and other engineering timber and bamboo products show that the BS has better mechanical properties. Finally, based on a comparison between various proposed compressive stress–strain relationship molds, this study modified the existing compressive strain–stress relationship model of the BS along the parallel grain direction. The modified multiorder function model has better prediction accuracy, providing a reference for theoretical analysis and related engineering applications of the BS.

Experimental Bond Behaviour of Glued-In Rod Connection for Mengkulang Glulam under Pull-Out Loading

Mechanical joint and adhesive joint are the two most common types of timber connections. In the case of timber construction, bonded-in rods offer a long-term, aesthetically acceptable alternative to some of the more conventional steel moment connections. Bonded-in rod connections in timber need many desirable attributes inefficiency, manufacture, performance, aesthetics and cost. This paper presents pull-out experimental testing for glued-in rod made of Mengkulang (tarrietia javanica) glulam joints. Hundred and seven (107) specimens were prepared, each with a single glued-in rod parallel and perpendicular to the grain. The steel treaded rod with a diameter of 12 mm, 16 mm and 20 mm with three numbers of adhesive (Sikadur-30) thicknesses of 2 mm, 3 mm and 4 mm were used in this experiment. The pull-out tests observations were on the effects of adhesive thickness, parallel and perpendicular grain directions and modes of failure of the specimens. The result obtained that 4 mm adhesive thickness was the strongest and parallel specimens showed better results than the perpendicular specimens. The pull-out failure modes are affected by the selected factors, i.e. the adhesive thickness, rod diameter and grain directions. Most of the specimens show failures in the timber besides the adhesive to timber interface.

Effects of core grain orientation on the mechanical properties of wood sandwich composite

Utilization of sandwich composite during recent year has been driven by the fact that compositematerial has ultimately high strength and stiffness by weight than any other materials. The skins ofsandwich composites technically bear most of the applied loads, however, the core materials alsoplay an important role as it functions in providing continuous support to resist the shear stress.Hence, proper selection of core materials is required to establish a sturdy sandwich compositestructure. This paper presents an experimental investigation on the sandwich structure consists offibreglass/epoxy face skins and a mahang wood core. Sandwich composite with core grain orientedin parallel and perpendicular to the flat plane direction were tested for mechanical performance intension, compression and flexure. The results indicate that sandwich composite with grain orientedin parallel direction performed better in tensile properties with strength of 201.98 MPa whereassandwich composite with perpendicular core grain produced a higher value of compressionproperties with strength of 70.11 MPa. However, no significant effect of grain orientation wasobserved in flexural strength. The strength of sandwich composite is dependent on the grainalignment of the wood core as it functions exclusively as mechanical supporting cells to supportthe wood structure.

Factorial Analysis of Tensile Properties of Areca Leaf Sheath (ALS) Subjected to Flattening

Areca leaf sheath (ALS) is a common agricultural waste produced in Southeast Asia countries, which is widely utilized over the decades to make biodegradable disposable dining wares. The workable surface of ALS for heat pressing is limited due to the concavity in the middle and folding at the edges of ALS. This study proposes that the ALS is flattened using a padding mangle prior to the forming process. The aim is to investigate the effect of ALS thickness and flattening pressure on the ultimate tensile strength and strain at break of ALS. A range of factors influencing the flattening process were investigated using design of experiment (DOE) approach based on analysis of variance (ANOVA). As the applied pressure increases, the thickness reduction of the ALS also increases. The tensile test was carried out in accordance to ASTM D3039 standard. It is found that ALS thickness and flattening pressure affect the results differently. The highest ultimate tensile strength (23.25 MPa) is obtained from 3-4 mm thick grain direction samples flattened at 5 bar; whereas the highest strain is 58.28% from perpendicular grain direction samples flattened at 1 bar, with thickness range of 3-4 mm. The results suggest that flattening process does not influence the tensile strength of ALS significantly when it is fed in parallel direction; but decreases the strain slightly.

Static Bending Performance of Mengkulang and Kasai LVL Beam in Structural Size

The scarcity of good quality timber initiates the timber industry shift to engineered timber products. Laminated veneer lumber (LVL) promising high strength and more dimensionally stable as well as flexible compared to conventional timber components. However, most of the previous studies focus on softwood timber, and limited species utilized tropical timber. Thus, this study assessed the static bending performance of LVL produced from Malaysian tropical hardwoods, namely Mengkulang (Heritiera spp.) and Kasai (Pometia spp.) in structural size. A four-point bending test was conducted in accordance with BS EN 408:2010+A1:2012. The effect of loading direction in edgewise to the bending test sample are performed and evaluated in parallel and perpendicular to the timber grain. In this study, Kasai samples displayed higher bending strength in MOR and MOE values than Mengkulang samples. By grain directions, samples with grain parallel to span performed better in MOR and MOE values as compared to the perpendicular grain samples for both timber species.

Características físicas de grãos de feijão-fava rajada (Phaseolus lunatus L.)

O conhecimento das propriedades físicas dos produtos agrícolas apresenta um relevante papel no estudo dos processos industriais de colheita e pós-colheita, visando obter melhores condições de dimensionamento de equipamentos e armazenamento. Assim, o presente trabalho tem como objetivo avaliar os efeitos da secagem e de diferentes cultivares nas propriedades físicas dos grãos de feijão-fava rajada. Foram avaliados 4 tratamentos, nos quais as amostras de grãos in natura produzidos no estado da Paraíba e Pernambuco foram submetidas ao processo de secagem por 30 h a 45 °C e umidade relativa do ar de 62%. Os tratamentos foram avaliados quanto aos parâmetros teor de água, atividade de água, massa individual do grão, massa específica real e aparente, ângulo de repouso dinâmico e dimensões do grão (a, b, c), além de terem sido obtidos os dados de porosidade e volume do grão. Observou-se que o processo de secagem influencia as propriedades físicas do material, proporcionando um aumento das massas específicas aparente e real. Os valores de atividade de água, massa individual, volume, porosidade, ângulo de repouso dinâmico e dimensões mutuamente perpendiculares dos grãos decresceram após a redução do teor de água. A esfericidade foi influenciada de forma distinta entre os tratamentos devido ao encolhimento desuniforme nas dimensões características durante o processo de secagem.

Impact properties of half stress-relieved and hot isostatic pressed Ti–6Al–4V components fabricated by laser powder bed fusion

This study focuses on the impact properties of Ti–6Al–4V produced by LPBF using un-notched Charpy impact testing. The effects of the build orientation, impact orientation, and half stress-relief and hot isostatic press (HIP) heat treatments on the impact resistance were investigated. The impact properties of HIPed samples were significantly greater than those of stress-relieved ones. Microstructural analysis and fractography revealed that process defects such as porosity, and columnar grain boundaries play an important role in crack initiation and propagation in the stress-relieved samples. In the HIPed samples the orientation of prior-β grain boundaries with respect to the impact loading, and impact energy absorption by microstructural modification from the high strains promoting formation of globular α were the main contributors in the impact resistance of the samples. Consequently, the vertically-built HIPed samples demonstrated the greatest impact energy from the combination of the perpendicular prior-β grain boundaries to the impact and highest observed α globularization.

Electrochemical analysis of high-performance protonic ceramic fuel cells based on a columnar-structured thin electrolyte

High-performance and cost-effective fabrications should be simultaneously achieved for practical applications of fuel cells. Unfortunately, protonic ceramic fuel cells, which are considered next-generation solid oxide fuel cells operating at lower temperatures (≤600 °C), do not satisfy the requirements. While thin electrolyte and rapid reactions at electrode/electrolyte interfaces are crucial for cell performance, the thickness of the electrolyte via cost-effective ceramic processes is still not satisfactory (currently capable of >10 μm) and the electrode reaction(s) are yet to be clarified. Here we demonstrate the fabrication of a columnar-structured thin electrolyte (∼2.5 μm) of BaCe0.55Zr0.3Y0.15O3-δ, in which no perpendicular grain boundaries exist against the current direction, through a low-cost screen printing method. A high open-cell voltage of 1.10 V ensures that the thin electrolyte is sufficiently dense for gas-tightness, thereby achieving an extraordinary maximum power density of 350 mW/cm2 at 500 °C. The electrode reactions are investigated by distribution of relaxation time method based on electrochemical impedance spectroscopy as a function of oxygen partial pressure and hydrogen partial pressure at 500 °C, suggesting that the reaction step corresponding to the surface diffusion of an adsorbed oxygen to the triple phase boundaries at the cathode is most probably the main contributor to the overall polarization resistances.

High-Performance Recessed-Channel Germanium Thin-Film Transistors via Excimer Laser Crystallization

This letter demonstrates the excimer laser crystallization (ELC) of germanium (Ge) thin films with the recessed-channel (RC) structure for high-performance p-channel Ge thin-film transistors (TFTs). Using ELC, large longitudinal grains with a single perpendicular grain boundary (GB) in the center of the recessed region were formed. This can be attributed to the lateral grain growth from un-melted Ge solid seeds in the thick region toward the complete melting recessed region during ELC. Consequently, the proposed p-channel RC-ELC Ge TFTs possessing large longitudinal grains without the perpendicular GB in the channel region exhibited a superior field-effect hole mobility of 447 cm2V−1s−1 with minor performance deviation.

(Invited) Ion-Transport in Polymer-in-Ceramic Electrolytes

Solid electrolytes could revolutionize battery and supercapacitor technology because of their nontoxicity, stability during operation and enhanced safety. The major limitation of solid electrolytes is their low ionic conductivity at room temperature, and intricate ion transport complicated by grain-boundary phenomena. We have developed, and present here, novel polymer-in-ceramic composite electrolytes with high ion-conduction properties, prepared by electrophoretic deposition. Nanoparticles of LiAlO2, Li10SnP2S12, and some ion-conducting glasses were used as ceramic matrices. Polyethyleneimine (PEI) and polyethylene oxide (PEO) were tested as binders and lithium-ion-conducting media. Our recently developed simplified Poisson-Boltzmann model reveals that the adsorption of PEI on the surface of ceramic particles increases zeta potential, repulsion forces between the particles and their deposition rate. The electrophoretic deposition of PEO and nanoceramic powders occurs from the individual entities. We have succeeded in depositing films containing 5 to 40% PEO which are homogeneous in composition and uniform in thickness. XRD and DSC tests showed that the crystallinity of the polymer confined in the pores of ceramics, is suppressed. This was expected to improve the ionic conductivity of composite electrolytes saturated with LiI salt. However, on the basis of AC-impedance, NMR and high-resolution X-ray tomography data, we suggest that the high ionic conductivity (0.5mS/cm) at room temperature and low activation energy (2.3kJ/mole) are brought about by the grain-boundaries current path between the excess of LiI and ceramic nanoparticles, and not by the confined-in-ceramic polymer. The nanoarchitecturing of ordered, fast-ion-conduction paths and the elimination of perpendicular blocking grain boundaries is expected to reduce the effect of high-resistant grains.

Demagnetization dynamics of C-doped FePt film

Magneto-optical information storage has been a hot research subject for several years. FePt exhibits abundant physical properties and has received much attention as a candidate material. Its alloy film with perpendicular anisotropy and small grain size has important applications in magnetic recordings due to the large intrinsic magnetic anisotropy which ensures long-time thermal stability of nanometer sized bits. However, the large coercive field of FePt is a significant factor that hinders its application. As is well known, the magnetic anisotropy in FePt alloy can be precisely modulated by carbon-doping, and as a result, the coercive field of FePt film can be modified effectively with the carbon dopant. On the other hand, the microscopic mechanism of magnetic storage relies on the motion of spin system. Ultrashort femtosecond laser has been demonstrated to be a very effective tool to investigate the dynamical coupling among different degrees of freedom, such as electron, spin and lattice in a ferromagnetic film. The research on spin dynamics has become a new frontier of condensed matter physics, which is crucial for ultrafast magnetic recording materials. In this work, by using the time-resolved magneto-optical Kerr effect spectroscopy, we study the ultrafast spin dynamics of two FePt alloy films with different carbon dopants under the applied magnetic field along the film surface. The FePt alloy films with different carbon dopants are fabricated on silicon substrates by the sputtering method. The main experimental findings in this work are as follows. (i) The transient Kerr signal is linearly proportional to the magnetization with the magnetic field up to 0.8 T, while the transient reflectivity of the film is independent of the applied magnetic field. (ii) For FePt alloy films with different coercive fields, it is found that the demagnetization time of the film with smaller coercive field is significantly faster than that of the larger counterpart: the former shows 0.8 ps demagnetization time, and the latter has a magnitude of 1.2 ps. The demagnetization times for both soft and hard magnetic films are independent of the applied magnetic field. (iii) With ultrafast laser pulse radiation, we observe the propagation of acoustic phonon with a resonance frequency of ～ 49 GHz, and the frequency of the acoustic phonon is independent of the applied magnetic field. From the above, the spin dynamics of the samples shows strong correlation with carbon-doping. Our experimental findings are desired for basic research as well as for the design and development of novel magneto-optical devices.

A thermophysical study on the freeze drying of wooden archaeological artifacts

Abstract The protection of unearthed waterlogged archaeological artifacts is a heavy task when large-scale construction is carried out in today's China. Freeze drying offers an efficient way for preserving wooden artifacts. In order to rationally design the freeze drying process, thermophysical studies were carried out in this paper. The measurements of water vapor diffusion coefficient and thermal conductivity were made. The impacts of cooling velocity and grain orientation on effective diffusion coefficient of water vapor, D, in dried wood were investigated. At low cooling velocity, 0.2 K/min, D was (4.8 ± 0.4) × 10 −4 m 2 /s in parallel grain direction, or (1.9 ± 0.4) × 10 −4 m 2 /s in perpendicular grain direction; at higher cooling velocity, 3.0 K/min, D was (4.3 ± 0.2) × 10 −4 m 2 /s in parallel grain direction, or (1.2 ± 0.1) × 10 −4 m 2 /s in perpendicular grain direction. The thermal conductivity of the dried sample was in the range of 0.78–1.06 W/(m·K). With the values attained, one-dimensional pseudo-steady analysis were made for the primary drying process of a cylinder and a flat slab. It was found that the process was mass-transfer controlled and the difference between surface temperature and sublimation temperature was very limited. Thus only mass transfer equation needed to be solved with assumption of constant sublimation temperature. The primary drying of a two-dimensional object was also simulated to predict the time required. Monitoring the surface temperature of each artifact and handling artifacts with similar drying time in a batch are proposed for the freeze drying of archaeological artifacts. The freeze-dried wooden artifacts by the authors yielded very small deformations.

The Development of Perpendicular Magnetic Recording Tape By Roll-to-Roll In-Line Sputtering

A method was developed that was capable of producing a 1000 m length of sputter-deposited magnetic tape using a roll-to-roll in-line sputtering system. This method produced a magnetic recording structure having perpendicular magnetic orientation and uniform grain size, which was observed over the full length of the sputtered area. The potential read/write performance of 60 Gb/in <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> areal density and good durability were also observed. Therefore, the possibility of utilizing sputter-deposited tape production for high recording density media was evident.

The thermal crack characteristics of rolled tungsten in different orientations

Thermal shock resistance of rolled tungsten with elongated grains aligned parallel and perpendicular to the loading direction was examined. Parallel (type A) or perpendicular (type B) grain orientations influences crack characteristics including threshold, profile, pattern and parameter. Type B samples show a cracking threshold of 0.44–0.66GW/m2, which is much higher than type A samples (<0.22GW/m2). For type A samples, primary cracks appear with linear profiles and dense secondary cracks along grain boundaries. Type B samples exhibit circular primary crack profiles as the homogeneous bending strength on the loaded surface and no secondary cracks are observed. Type A samples exhibit deeper cracking (550–850μm) than type B samples (350–550μm). The maximum crack widths were 2–8μm for type A, again larger than those of type B (0–8μm). Thermal fatigue tests were performed on type B samples, and cracks were detected after 1000cycles.

Thermal Conductivity of Akar Bamboo (&lt;i&gt;Dendracalamus pendulus&lt;/i&gt;) and Semantan Bamboo (&lt;i&gt;Gigantochloa scortechinii&lt;/i&gt;)

Bamboo is known as economically and environmental friendly plant. The most common application of bamboos is furniture and traditional handcrafts. Many studies on mechanical and physical properties of bamboo have been conducted. However the thermal insulation property of these abundance species has never been recognized and commercially utilized which results in the reason why thermal properties of bamboo have never been studied. In this experiment, two species of bamboo which are Akar bamboo (Dendracalamus pendulus) and Semantan bamboo (Gigantochloa scortechinii) has been tested to determine their thermal conductivity. The test samples were prepared to conduct this experiment in parallel and perpendicular grain direction towards the heat source. Wood adhesive was used as the binder for cylindrical laminated bamboo. The result shows that thermal conductivity of bamboo is low in perpendicular direction towards the heat source compared to the parallel direction. Different species of bamboo also give significant result on thermal conductivity hence improved the insulation properties of the bamboo.

High-Performance SLS Nanowire TFTs With Dual-Gate Structure

Gate-all-around (GAA) sequential-lateral-solidification (SLS) nanowire (NW) thin-film transistor (TFT) devices with single-gate and dual-gate structures are fabricated and characterized. Compared with planar SLS TFT, owing to only one perpendicular grain boundary in each NW channel, GAA SLS NW TFT with single-gate structure can exhibit better performances when operated at low gate/drain voltage. However, it suffers from an obvious kink effect when operated at high gate/drain voltage because of the local electrical fields located at the sharp corners in GAA structure. Via dual-gate structure design, it clearly improves the performance of TFT device, which thus has a lower leakage current, a higher ON/OFF ratio, and an improved kink effect as compared with single-gate TFTs by avoiding the perpendicular grain boundaries and reducing electrical fields near channel/drain junction regions. In addition, the device reliability, such as the threshold voltage shift, subthreshold swing, and transconductance degradation under dc hot-carrier stress, is apparently improved by the proposed structure.

Deuterium Retention in Tungsten with Different Grain Elongation Direction Irradiated by Plasma in APSEDAS

Deuterium retention after the low energy plasma irradiation was investigated using the polycrystalline tungsten samples of which grain elongation directions are parallel and perpendicular with respect to the surface. Fluence dependence of the retention measured by means of thermal desorption spectroscopy showed that it is 2-5 times larger for the sample with the perpendicular grain elongation. Thermal desorption of trapped deuterium has been modeled under the fast diffusion assumption with the defects trapping energy of about 2 eV. Possible mechanism of the deuterium retention and thermal desorption has been proposed.

A close observation on the deformation behavior of bicrystal copper under tensile loading

Tensile deformation behavior of a copper bicrystal with a perpendicular grain boundary was investigated. The deformation distribution on specimen surface during test was obtained by using digital image correlation (DIC) method. Experimental results show that the specimen deforms in a ‘double-necking’ mode. Both the displacement and strain distributions on specimen surface are inhomogeneous, and strain level at the grain boundary is lower than that within the grains. The specimens always fracture at the interior of the grain with soft orientation. In situ tension tests by scanning electron microscopy (SEM) indicate that slip bands cannot pass through the grain boundary. The above results suggest that the tensile deformation behavior of copper bicrystal is determined by the orientation of each grain as well as the grain boundary property. Grain with soft orientation tends to deform plastically and fracture first. Large-angle grain boundary could impede slip bands and hence strengthen the material.

La0.8Sr0.2Ga0.8Mg0.2O3 − δ thin films for IT-SOFCs: Microstructure and transport properties correlation

Highly textured La0.8Sr0.2Ga0.8Mg0.2O3 (LSGM) films with columnar structure were grown by pulsed laser deposition on (001) NdGaO3 and SrTiO3 buffered (001) MgO substrates. Combined analysis of the films structure and morphology and EIS measurements showed that the transport properties are mainly limited by perpendicular grain boundaries effects. Increasing the film thickness, columnar nanosized grains tend to coalesce leading to a decrease of grain boundary concentration, hence to enhanced conductivity.