Search Results (88)

This paper presents an analysis of the ultimate strength of wooden joints of the structures of ancient wooden ships. The aim is to contribute to the discussion about how joining technology and types of joints contributed to the transition from ‘shell-first’ to ‘frame-first’ construction, of which the latter is still traditional Mediterranean wooden shipbuilding technology. Historically, ship construction has consisted of two main structural types of elements: planking and stiffening. Therefore, two characteristic carvel planking joints and two longitudinal keel joints were selected for analysis. For planking, the joint details of the ship Uluburun (14th c. BC) and the ship Kyrenia (4th c. BC) were chosen, while two different types of scarf joints belonging to the ship Jules-Verne 9 (6th c. BC) and the ship Toulon 2 (1st c. AD) were selected. The capacity, i.e., the ultimate strength of the joint, is compared to the strength of the structure as if there was no joint. The analysis simulates the independent joint loading of each of the six numerical models in bending, tension, and compression until collapse. The results are presented as load-end-shortening curves, and the calculation was performed as a nonlinear FE analysis on solid elements using the LSDYNA explicit solver. Since wood is an anisotropic material, a large number of parameters are needed to describe the wood’s behaviour as realistically as possible. To determine all the necessary mechanical properties of two types of wood structural material, pine and oak, a physical experiment was used where results were compared with numerical calculations. This way, the material models were calibrated and used on the presented joints’ ultimate strength analysis. Full article

Fast-growing hardwoods like poplar often lack natural durability in outdoor use and require homogeneous impregnation with protective agents, though achieving homogeneity remains a known challenge. Various anatomical structures influence fluid transport in wood. This study compares characteristics of pits in libriform fibres, between ray–vessel interfaces, and between vessel-to-vessel connections in normal wood and tension wood of a hybrid poplar genotype (Populus × canadensis, ‘Gelrica’), including both impregnated (with an aqueous, dye-containing solution) and non-impregnated regions, to identify anatomical barriers to impregnation. Light and scanning electron microscopy revealed significant differences in pit morphology and frequency in libriform fibres between normal wood and tension wood. In non-impregnated regions, pits were often encrusted. Vessel–ray pits did not differ between normal wood and tension wood but showed distinct differences between impregnated and non-impregnated regions: in the latter, pits were occluded by tylose-forming layers. Intervessel pits differed in border and aperture size between earlywood and latewood in both normal wood and tension wood. Hence, fluid transport is strongly impeded by occluded vessel–ray pits and, to a lesser extent, by encrusted fibre pits. Full article

Torrefaction is a thermochemical pretreatment in which biomass is heated at 200–300 °C for 30–60 min in an inert atmosphere. Torrefaction has been previously used to improve the fuel properties of lignocellulosic biomass; however, the use of torrefaction for bioenergy generation represents a low-value final product as well as the dead end of the biomass value chain. Herein, we demonstrate the proof-of-concept for the utilisation of torrefaction as a pretreatment to convert low-value wood waste into biosurfactants, a high-value specialty biochemical. Wood waste was torrefied at 225 °C, 250 °C, 275 °C, and 300 °C and physicochemically characterised using proximate and ultimate analyses, FTIR, XRD, TGA–DTG, and SEM–EDX to assess its suitability as fermentation feedstock. Aspen waste torrefied at temperatures less than 250 °C was directly utilised by Burkholderia thailandensis DSM 13276 via semi-solid-state fermentation to yield biosurfactants, and 225 °C was selected for further experiments as it resulted in the production of biosurfactants which reduced the surface tension of the production medium to 36.8 mN/m and had an emulsification index of 64.1%. Tension and emulsification activities decreased with the increase in torrefaction temperature. The biosurfactant derived from torrefaction at 225 °C formed highly stable emulsions with diesel oil (lasting >40 days), in addition to low interfacial tension, suggesting potential applications in diesel bioremediation. This integrated, chemical-free strategy offers an alternative application for torrefied wood waste as well as a feasible solution for the cost-effective chemical-free production of biosurfactants, incorporating circular economy principles. Full article

Drying constitutes an essential step in aerogel fabrication, where the drying method directly determines the pore structure and consequently influences the material’s functionality. This study employed various drying techniques to prepare balsa-wood-derived aerogels, systematically investigating their effects on microstructure, density, and performance characteristics. The results demonstrate that different drying methods regulate aerogels through distinct pore structure modifications. Supercritical CO₂ drying optimally preserves the native wood microstructure, yielding aerogels with superior thermal insulation performance. Freeze-drying induces the formation of ice crystals, which reconstructs the microstructure, resulting in aerogels with minimal density, significantly enhanced permeability, and exceptional cyclic water absorption capacity. Vacuum drying, oven drying, and natural drying all lead to significant deformation of the aerogel pore structure. Among them, oven drying increases the pore quantity of aerogels through volumetric contraction, thereby achieving the highest specific surface area. However, aerogels prepared by air drying have the highest density and the poorest thermal insulation performance. This study demonstrates that precise control of liquid surface tension during drying can effectively regulate both the pore architecture and functional performance of wood-derived aerogels. The findings offer fundamental insights into tailoring aerogel properties through optimized drying processes, providing valuable guidance for material design and application development. Full article

Various pretreatment methods, often employed in wood biorefineries, aim to disrupt the wood architecture, thereby enhancing the efficiency of hemicellulose extraction for increasing the production of bio-ethanol, bio-gas, and bio-oil, as well as improving the pulping process. Pretreatment for the pulping process has advantages such as enhanced yield in biorefined products and reducing chemicals and energy consumption. This study examined the effect of an alkaline hydrolysis of birch sawdust on the chemical composition, aggregation ability, and surface activity of soda lignin obtained by soda pulping. The alkaline hydrolysis of birch sawdust led to a remarkable removal of hemicellulose and reduced its mechanical strength. The resorption of lignin fragments on the lignocellulosic matrix during the hydrolysis was observed. The soda pulping of the original and the treated sawdust was carried out under laboratory conditions at 165 °C for 90 min, using 4.5% sodium hydroxide. A higher yield of soda lignin and pulp was obtained from the treated sawdust. The reduced content of acidic and methoxyl groups in the chemical composition of the soda lignin from the hydrolyzed sawdust was explained by the predominance of polycondensation reactions in forming its primary structure. The changes in size and zeta potential values of the formed lignin particles, as well as in the modality of the size distribution with decreasing pH, were studied. The early-proposed suggestion about the existence of structural complementarity in the formation of the ordered lignin supermolecular structures has been testified. The higher surface activity at the air–water interface for the soda lignin extracted from the hydrolyzed sawdust, compared to the lignin from the original residue, was mainly attributed to a lower content of the acidic groups in its chemical composition, shifting the hydrophilic–hydrophobic balance of its structure toward hydrophobicity. Full article

The aim of this study was to determine the influence of initial chain tension, feed force, and wood hardness on the variability of the cutter’s deflection angle during petrol chainsaw operation. Cutting wood with a chainsaw is a complex process that has not been fully elucidated to date. During operation, the position of cutters with respect to the workpiece may vary. The situation is additionally complicated by the fact that chainsaws are powered by one-cylinder gasoline engines characterized by highly variable instantaneous rotational speeds. The experiments involved two types of wood (pine and oak), two initial tension values (tight vs. slack chain), and two feed forces (20 N and 80 N). The cutting process was recorded with a high-speed camera at 12,000 fps to determine cutter deflection angles, instantaneous speeds, and accelerations for all the aforementioned cases. It was found that at the lower feed force the cutter deflection differed depending on the initial chain tension, and a greater cutter deflection angle was observed in pine wood processing. It was also found that speed and acceleration in the Y axis were much lower than in the X axis. Additionally, the rear part of the cutter revealed greater speed variation in the X axis. Full article

The bending test is a good indicator of wood characterization, including compression, tension, and shear stresses. Therefore, many studies have been published on bending tests for wood. Its heterogeneous structure, anisotropic behavior during the physical and mechanical tests, and anatomical and chemical differences due to species and growing area make the characterization difficult. Accordingly, research has focused on mathematical models and simulation programs for predicting material characteristics. More data on using many wood species in such models or programs still need to be collected. This study aimed to eliminate these deficiencies for two softwood species grown in Türkiye. In this context, three- and four-point bending tests were performed on 5656 samples from fir (Abies spp.) and black pine (Pinus nigra) species that were collected from 13 regions. A nonlinear material model was generated from the load-deformation data for both species, and the results were found in agreement regarding the bending features of both softwood species. The results show that nonlinear numerical modeling could predict the bending results with significant rates (min. 94%). Additionally, bending characteristics such as limits of proportionality (LOP), and elastic potential were found and compared between and within the species, regions, and test methods. Load-deformation curves showed that the LOP ranged between 40% and 60% of the maximum load, which was higher than the theoretical approach in the standards. Full article

The study addresses the underutilisation of wood in construction in Chile, particularly given the country’s robust forestry sector. The research investigates perceptions, tensions, and contradictions among end-users regarding timber construction in Valdivia, a city with a mixed forestry industry. Methods included a comprehensive survey of 96 households across various socioeconomic clusters, utilising descriptive and exploratory statistical analyses. Key findings reveal persistent negative perceptions about wood’s durability, fire resistance, and maintenance costs. However, positive aspects, such as lower construction costs and adequate thermal comfort, were also noted. Surprisingly, concerns were raised about wood’s environmental impact, including deforestation and its role in combating climate change, contrasting with the material’s known ecological benefits. The study concludes that these perceptions are deeply influenced by ideological and sociopolitical factors, suggesting that mere marketing strategies may not suffice to alter public opinion. Instead, a collaborative effort involving public policy, industry advancements, and transparent scientific communication is essential to promote the benefits of timber construction and address the entrenched biases. Full article

This paper describes an innovative method developed by the authors to support basic decisions concerning the structural restoration of a large historical panel painting which had been damaged by inappropriate attachment to a wall and ongoing exposure to severe changes in environmental humidity. The Lapidazione di Santo Stefano is a large panel (2.78 × 3.92 m²) painted by Giorgio Vasari in 1571 and has been housed since then in the Church of Santo Stefano dei Cavalieri in Pisa (Italy). Its wooden support is made of large horizontal planks glued together along their edges and stiffened by vertical, dovetailed crossbeams. The panel was tightly fastened to a church wall with several rigid bolts; due to the moisture cycling produced by rainwater leakage and a subsequent “compression set”, it had developed severe tension stresses perpendicular to the grain, resulting in cracks affecting both the wood and the paint layers. To decide how to carry out the structural restoration of the panel, it was necessary to know whether slippage could occur between the panel and crossbeams during seasonal variations in environmental humidity. Without slippage, tensile stresses would be generated in the wood and could produce further cracks and damage the paint layers. An in situ monitoring method for assessing the possibility of slippage was developed and implemented. An analysis of data collected over a period of 6 months before the structural restoration confirmed that adequate slippage was possible; hence, the decision to fully repair the cracks was taken. Monitoring continued for a year after restoration and confirmed the previous findings. This paper describes the monitoring method, the equipment used, the results of its implementation and its value as a preventive conservation tool. Full article

Trembling aspen (Populus tremuloides) is one of the major species within Populus, a predominant genus of hardwoods in North America. However, its utilization has been limited to pulp and paper or wood-based composite boards. This study aimed at evaluating the major physical and mechanical properties of trembling aspen lumber, with an ultimate objective of using this species to produce engineered wood products (EWPs). The testing materials consisted of 2 × 4 (38 mm × 89 mm) trembling aspen lumber pieces in lengths of 8, 10, and 12 feet (2.44, 3.05, and 3.66 m) with two visual grades, select structural (SS) and No. 2. Machine Stress-Rated (MSR), and longitudinal stress wave (LSW), edgewise third-point bending (EWB), and axial tension tests were conducted on the lumber. It was found that, (1) by increasing the maximum knot size by a half-inch from one-quarter inch, the minimum modulus of elasticity (MOE) measured using the MSR, the mean, and the fifth-percentile ultimate tensile strength (UTS) decreased by about 8.8%, 20.1%, and 29.8%, respectively. (2) Approximately 44% of the trembling aspen lumber met the 1450f-1.3E grade for MSR lumber, and 62% qualified for the 1200f-1.2E grade. (3) There was a great potential for manufacturing cross-laminated timber (CLT) of grade E3, with a rejection rate of about 29%. (4) The mean UTS and MOE values of the SS-grade trembling aspen lumber were 22.88 MPa and 9519 MPa, respectively, being 25.5% and 11.3% lower than that of Spruce–Pine–Fir (S-P-F) lumber. The fifth-percentile UTS and MOE values were 11.57 MPa and 7404 MPa, respectively, marking a decrease of 13.3% and 1.5% compared to the S-P-F lumber. (5) The oven-dried specific gravity (SG) of the trembling aspen wood was 0.40, which was about 3.5% larger than the value provided in the Wood Handbook. Full article

As civilization and technology have developed, there have been multiple energy transitions that have pushed various resources like coal, wood, oil, and gas to the forefront of the energy mix. Due to a variety of geopolitical initiatives, there have been progressively more restrictions on the energy sector in recent years. One of the main concerns of researchers is the widespread use of renewable energy and the replacement of fossil resources. The utilization of non-renewable energy sources results in a detrimental increase in greenhouse gas emissions. One of the most crucial strategies for lowering energy consumption and enhancing the energy system’s sustainability is to increase energy efficiency. Numerous studies note that energy transition has become necessary in the modern day. Using the analysis of the main components as an extraction method, hierarchical cluster analysis, this study focuses on the situation of the states of the European Union in their race for energy transition, taking into account the main challenges generated by geopolitical tensions and the energy poverty spectrum for the population. The conclusions of the study call for a reconfiguration of the energy mix based on renewable energy. Increasing the share of renewable energy is a goal pursued by EU countries, but energy policies must be considered in a broader context that includes the social aspects of the energy transition. So, just transition is a new concept that reshapes the actions of public authorities on the path to a low-carbon economy. Just transition is a necessity that puts the consumer at the center of attention so that the negative externalities generated by the move away from fossil fuels are minimized in terms of social impact. Full article

With a rising interest in smart windows and optical displays, the utilization of metal oxides (MOs) has garnered significant attention owing to their high active sites, flexibility, and tunable electronic and optical properties. Despite these advantages, achieving precise tuning of optical properties in MOs-based quantum dots and their mass production remains a challenge. In this study, we present an easily scalable approach to generate WO₃ quantum dots with diverse sizes through sequential insertion/exfoliation processes in solvents with suitable surface tension. Additionally, we utilized the prepared WO₃ quantum dots in the fabrication of luminescent transparent wood via an impregnation process. These quantum dots manifested three distinct emitting colors: red, green, and blue. Through characterizations of the structural and optical properties of the WO₃ quantum dots, we verified that quantum dots with sizes around 30 nm, 50 nm, and 70 nm showcase a monoclinic crystal structure with oxygen-related defect sites. Notably, as the size of the WO₃ quantum dots decreased, the maximum emitting peak underwent a blue shift, with peaks observed at 407 nm (blue), 493 nm (green), and 676 nm (red) under excitation by a He-Cd laser (310 nm), respectively. Transparent woods infused with various WO₃ quantum dots exhibited luminescence in blue/white emitting colors. These results suggest substantial potential in diverse applications, such as building materials and optoelectronics. Full article

Within the search for alternative sustainable materials for future transport applications, wood veneer laminates are promising, cost-effective candidates. Finite element simulations of progressive damage are needed to ensure the safe and reliable use of wood veneers while exploring their full potential. In this study, highly efficient finite element models simulate the mechanical response of quasi-isotropic ${[90/45/0/-45]}_s$ beech veneer laminates subjected to compact tension and a range of open-hole tension tests. Genetic algorithms (GA) were coupled with these simulations to calibrate the optimal input parameters and to account for the inherent uncertainties in the mechanical properties of wooden materials. The results show that the continuum damage mechanistic simulations can efficiently estimate progressive damage both qualitatively and quantitatively with errors of less than 4%. Variability can be assessedthrough the relatively limited number of 400 finite element simulations as compared to more data-intensive algorithms utilised for uncertainty quantification. Full article

The investigation conducted in this study focused on assessing the withdrawal resistance of T-joints and the bending moment capacity in the tension and compression of corner joints. For samples, preparation glued-in loose tenons (Domino dowels) and dismountable connectors were used as connecting elements. The joints were made of European beech wood and a D3-grade PVAc adhesive was utilized for bonding. The effect of the joint type, the shoulders’ bonding, and the load application direction were investigated. The test results revealed that the withdrawal resistance of Domino dowel joints exhibited twice the strength compared to Domino connectors. Moreover, the presence of a bonded area on the shoulders did not significantly impact the strength of the joints. In the case of corner joints, the bending moment capacity in compression was notably influenced by the bond line on the shoulders, although such an effect was not significant in tension. Domino dowel joints provided a robust and reliable permanent connection between wooden elements, surpassing Domino connectors; however, in both cases, the strength values exceeded those of conventional dowels and cam lock connector joints. Full article

The field of nanotechnology has shown promise in addressing major problems and improving drilling effectiveness. An overview of the difficulties encountered during oil and gas well drilling operations and the demand for creative solutions opens the debate. This review explores how nanotechnology is transforming the oil industry and enhancing performance as a whole. The evaluation of the uses of nanotechnology for better oil recovery, real-time monitoring, innovative materials, drilling fluids, and reservoir characterization are extensively discussed in this review. The primary function of additives is to improve the fundamental characteristics of drilling fluids. The variety of fluid additives available is a reflection of the complex drilling–fluid systems that are currently being used to enable drilling in increasingly difficult subsurface conditions. Common additives used in water- and oil-based drilling fluids include lubrication, shale stability, filtration control, rheology control, viscosification, and pH regulation. Drilling fluids frequently contain filtration control additives such as starch, polyanionic cellulose (PAC), carboxymethyl cellulose (CMC), and nanoparticles (NP). Commonly used rheology-modifier additives are xanthan gum, carboxymethyl cellulose, guar gum powder, and, more recently, salt-responsive zwitterionic polymers that were used as viscosifiers to water-based drilling fluids. The three main additives that regulate pH are citric acid monohydrate, potassium hydroxide, and sodium hydroxide. Additives that stabilize shale, such as potassium and sodium salts and asphaltenes, are often used. A wide range of materials are included in the category of lubricating additives, including polymers, asphaltenes, glass beads, oils of various grades, and oil-surfactants. Various fibrous materials, including wood, cotton, fibrous minerals, shredded tires from vehicles, and paper pulp, are used as additives to control circulation. Furthermore, shredded cellophane, bits of plastic laminate, plate-like minerals like mica flakes, granulated inert materials such as nut shells, and nano-polymers are used in wellbores to reduce fluid loss. The incorporation of nanoparticles into drilling fluids has produced upgraded fluids with better features, including improved lubricity, thermal stability, and filtering capacities. These developments aid in lowering friction, enhancing wellbore stability, and enhancing drilling efficiency. This paper also emphasizes how nanotechnology has made enhanced drilling equipment and materials possible. Drilling equipment’s longevity and performance are increased by nanocomposite materials that have been reinforced with nanoparticles due to their improved mechanical strength, wear resistance, and thermal stability. Advanced reservoir characterisation tools, including nanoparticle tracers and nanoscale imaging methods, can help locate the best drilling sites and increase production effectiveness. On the other hand, nanofluids and nanoemulsions can potentially increase oil recovery because they enhance fluid mobility, lower interfacial tension, and alter rock wettability. Although nanotechnology has many advantages, there are also issues that need to be resolved. For an implementation to be effective, factors including nanoparticle stability, dispersion, and potential environmental effects must be carefully taken into account. This review highlights the need for future research to create scalable manufacturing procedures, improve nanoparticle behaviour, and determine nanomaterials’ long-term environmental effects. In conclusion, this in-depth analysis illustrates the use of nanotechnology in transforming the process of drilling oil and gas wells. Full article