Search Results (417)

Canadian sawmills commonly use chipper-canters to process softwood logs into squared lumber and wood chips for pulp mills. However, the declining demand for newsprint and print paper has led to an oversupply of wood chips, resulting in economic losses and environmental concerns. To address this issue, a strander-canter capable of producing both softwood cants and strands for oriented strand board (OSB) presents a promising alternative. This study evaluates the feasibility of using jack pine strands generated by a novel strander-canter equipped with a cutterhead for OSB strand production. Strands were generated from frozen and unfrozen logs under varying cutting parameters and incorporated in the core layer of the panels. Industrial aspen strands were used for the surface layers. OSB panels were assessed for mechanical and physical properties following the CSA O325:21 standard. Strand size distribution and vertical density profiles were also analyzed. The results indicated that panels made from jack pine strands demonstrated bending and internal bond properties that were either comparable to or superior to those of the control panels. However, including jack pine strands in the core layer increased the thickness swelling of the panels. Full article

This study proposes a novel LK-BP-AFPSO model for the nondestructive evaluation of wood mechanical properties, combining a backpropagation neural network (BP) with adaptive fractional-order particle swarm optimization (AFPSO) and Liang–Kleeman (LK) information flow theory. The model accurately predicts four key mechanical properties—longitudinal tensile strength (SPG), modulus of elasticity (MOE), bending strength (MOR), and longitudinal compressive strength (CSP)—using only nondestructive physical features. Tested across diverse wood types (fast-growing YKS, red-heart CSH/XXH, and iron-heart XXT), the framework demonstrates strong generalizability, achieving an average prediction accuracy (R²) of 0.986 and reducing mean absolute error (MAE) by 23.7% compared to conventional methods. A critical innovation is the integration of LK causal analysis, which quantifies feature–target relationships via information flow metrics, effectively eliminating 29.5% of spurious correlations inherent in traditional feature selection (e.g., PCA). Experimental results confirm the model’s robustness, particularly for heartwood variants, while its adaptive fractional-order optimization accelerates convergence by 2.1× relative to standard PSO. This work provides a reliable, interpretable tool for wood quality assessment, with direct implications for grading systems and processing optimization in the forestry industry. Full article

Fabric veneer panels were prepared using ethylene-vinyl acetate copolymer film (EVA) as the intermediate layer and poplar plywood as the substrate. Eight fabrics with different compositions were selected for evaluation to screen out fabric materials suitable for poplar plywood veneer. The fabrics were objectively analyzed by bending and draping, compression, and surface roughness, and subjectively evaluated by establishing seven levels of semantic differences. ESEM, surface adhesive properties, and peel resistance tests were used to characterize the microstructure and physical–mechanical properties of the composites. The results show that cotton and linen fabrics and corduroy fabrics are superior to other fabrics in performance, and they are suitable for decorative materials. Because the fibers of the doupioni silk fabric are too thin, and the fibers of felt fabric are randomly staggered, they are not suitable for the surface decoration materials of man-made panels. The acetate veneer surface gluing performance was 1.31 MPa, and the longitudinal peel resistance was 20.98 N, significantly exceeding that of other fabric veneers. Through the subjective and objective analysis of fabrics and gluing performance tests, it was concluded that, compared with fabrics made of natural fibers, man-made fiber fabrics are more suitable for use as surface finishing materials for wood-based panels. The results of this study provide a theoretical basis and process reference for the development of environmentally friendly decorative panels, which can be expanded and applied to furniture, interior decoration, and other fields. Full article

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

Bamboo, as a forest product material with good mechanical properties, is considered to be a future timber alternative due to its fast growth and accelerated reforestation potential. The use of OSB panels has significantly increased in the market and OSB has replaced traditional panels. Three different OSB panels coded Type 1, Type 2, and Type 3 were produced using bamboo and some mechanical properties were evaluated. Based on the results, Type 2 OSB panels yielded statistically higher bending strength values than Type 1 and Type 3 panels. There were no significant differences between the Type 1 and the Type 3 OSB panels. When the internal bonding (IB) values of the panels were examined, Type 3 yielded the highest values, followed by Type 2 and Type 1. However, it was observed that these resistance differences were not statistically significant. The only type of failure mode observed was brush-shaped separation from the center of the panels. The load–displacement graph of the OSB bamboo panels under bending load indicated a similar load-displacement curve of typical wood under bending load. Full article

This study utilizes waste wheat straw fibers and discarded tea bags as novel raw materials for developing new thermal insulation and sound absorption composites. Wood adhesive (WA) is used to bind the polymer raw materials. Loose polymers and different composites are experimentally developed in different concentrations. Sound absorption and thermal conductivity coefficients are obtained for the developed boards. Bending moment analysis and the moisture content of the boards are reported in addition to a microstructure analysis of the straw fibers from wheat. The results indicate that as the wheat straw fiber’s percentage increases in the composite, the thermal conductivity coefficient decreases, the flexure modulus decreases, the sound absorption coefficient increases at some frequencies, and the moisture content increases. The range of thermal conductivity and the noise reduction coefficient are 0.042–0.073 W/m K and 0.35–0.6 at 24 °C for the polymer raw materials, respectively. The corresponding values for the composites are 0.054 and 0.0575 W/m K and 0.45–0.5, respectively. The maximum moisture content percentages for the polymers and composites are 6.5 and 1.15, respectively. The composite flexure modulus reaches maximum and minimum values of 4.59 MPa and 2.22 MPa, respectively. These promising results promote these polymer and composite sample boards as more convenient insulation materials for green buildings and could replace the conventional petrochemical thermal insulation ones. Full article

Sustainability and the circular economy are increasingly recognized as global priorities, particularly in industrial waste management. This study explores the development of a sustainable composite material using wood waste and natural fibers, contributing to circular economy practices. Sandwich panels were manufactured with a green epoxy resin matrix, incorporating wood waste in the core and flax fibers in the outer layers. Mechanical tests on the sandwich panel revealed a facing bending stress of 92.79 MPa and a core shear stress of 2.43 MPa. The panel demonstrated good compressive performance, with an edgewise compressive strength of 61.39 MPa and a flatwise compressive strength of 96.66 MPa. The material’s viscoelastic behavior was also characterized. In stress relaxation tests (from an initial 21 MPa), the panel’s stress decreased by 20.2% after three hours. The experimental relaxation data were successfully fitted by the Kohlrausch–Williams–Watts (KWW) model for both short- and long-term predictions. In creep tests, the panel showed a 21.30% increase in displacement after three hours under a 21 MPa load. For creep behavior, the KWW model was preferable for short-term predictions, while the Findley model provided a better fit for long-term predictions. Full article

Engineered bamboo has been considered a viable replacement for traditional wood and steel for structural and architectural purposes due to its renewable nature, high strength, and compatibility with different processing techniques. This systematic review analyzed the literature on the mechanical properties and processing techniques of engineered bamboo products, which include bamboo scrimber and laminated bamboo. The literature included in this systematic review was extracted from the Engineering Village platform. The studies retrieved from this platform were filtered to only have been published in top journals (Q1/Q2) related to engineering materials, materials science, and the construction industry. Using this methodology, from the initial 191 identified records, 51 studies that were the most relevant were chosen. The review revealed that bamboo scrimber has better performance for specific mechanical properties, which include its compressive, tensile, and bending strength. Laminated products had higher variability, which was often caused by the type of adhesive, orientation, and quality of adhesion. This study also identified the details of manufacturing processes, such as the adhesive systems, pre-treatment methods, and pressing conditions used. Moreover, the literature exhibited considerable inconsistencies in testing standards, reporting practices, and long-term durability evaluations. This review highlights these challenges and provides recommendations for future research to resolve these issues. Full article

This article analyses the main effect and interaction of thermal modification, wood moisture content, frequency, and vibration direction on the damping of spruce wood. Samples were thermally modified at three different temperatures (180 °C, 200 °C, and 230 °C) and then equilibrated at four different relative humidities (RHs) (20%, 44%, 76%, and 88%). The specimens were then freely supported and excited with a hammer to vibrate freely. Damping at the frequencies of the first three bending vibration modes for vibrations in the radial (LR plane) and tangential (LT plane) directions was determined using the wavelet transform method, which enables a decoupling of the vibration modes and thus a precise and accurate determination of the damping values. Damping increases with the wood moisture content for different modification levels, whereby the damping in the LR vibration direction plane differs from the damping in the LT vibration direction plane. For an unmodified sample and at frequency at the first vibration mode, damping in the radial plane is greater than in the tangential plane, but the relationships change with RHs, modification levels, and vibration direction planes. The dependence of damping on various factors has a strong influence on the calculation of various acoustic indicators, where damping of the wood is considered for the calculation, since damping for the same sample differs depending on the direction of vibration and the frequencies at different vibration modes. Full article

We designed detachable steel sleeves to reinforce wooden joints and improve their integrity under earthquake action and investigated their mechanical properties. Monotonic bending tests were performed on a half-tenon pure wooden joint and a joint strengthened by a detachable steel sleeve. More obvious tenon pulling-out failure was observed in the pure wood joint; in comparison, only slight extrusion fracture of wooden beams and extrusion deformation of steel sleeves occurred in the wood joint reinforced by a detachable steel sleeve. Our test results showed that the initial rotational stiffness of the strengthened joint, JG1, was increased by 495.4% compared with that of the unstrengthened joint, JG0. The yield bending moment increased by 425.9%, and the ultimate bending moment increased by 627.5%, which indicated that the mechanical performance was significantly improved when the joint was reinforced by a detachable steel sleeve. Numerical simulations of different components were performed with finite element analysis software to analyze the mechanical performance of the reinforced joint. It was found that the stiffness and ultimate flexural performance of the joint could be increased by setting stiffeners on the steel sleeve and connecting the wooden column with self-tapping screws. The results of the tests were compared with those obtained through finite element analysis, and a high degree of accuracy was achieved, which could provide a theoretical basis for the reinforcement of timber structural buildings. Full article

Lightweight, layered wood-based panels are gaining attention due to favorable mechanical and physical properties. This study examined numerical modeling as a method to predict the strength of innovative three-layer sandwich panels with thermoplastic cores containing wood particles as the filler. Two core geometries (F and S) and two material formulations (60% HDPE + 40% sawdust, and 40% HDPE + 60% sawdust) were tested. The panels were produced without additional adhesives; bonding with high-density fiberboard (HDF) facings was achieved through the thermoplastic properties of the core. Mechanical properties such as bending strength (MOR), modulus of elasticity (MOE), and compressive strength perpendicular to the surface were measured. Results showed that both core geometry and material composition significantly influenced structural performance. Panels with the F profile showed better bending strength and stiffness (MOR—13.2 N/mm², MOE—2017 N/mm²), while the S profile had higher compressive strength (0.62 N/mm²). Numerical simulations using SolidWorks Simulation confirmed the experimental data, with stress and displacement distributions matching laboratory results. These findings demonstrate the potential of thermoplastically formed cores for creating lightweight, recyclable wood-based composites with tailored mechanical properties. Full article

The natural variability and moisture sensitivity of bamboo limit its widespread use in construction applications. To address these challenges, densification and delignification processes have emerged as promising modification techniques. Densification and delignification processes can lead to significant improvements in the physical, mechanical, and chemical properties of solid wood. In this study, a two-step process of delignification and densification was carried out on Dendrocalamus asper bamboo specimens. The objective was to assess whether the optimized parameters of densification for natural bamboo on an open pressing system can be transferred for delignified bamboo. Delignification was achieved using an alkali solution (NaOH and Na₂SO₃) with two different temperature settings (25 °C or 100 °C). The pre-treated samples were dried in one of the two different conditions, either at 100 °C for 24 h or 25 °C for 30 days, resulting in four different groups with an average moisture content ranging from 7 to 10%. The samples were densified to 50% of their original thickness through an open thermo-mechanical press system at 160 °C with a compression rate of 6.7 mm/min and compared to densified bamboo without delignification (reference). The compression stress required to achieve a 50% degree of densification was evaluated, with untreated samples exhibiting an average value close to 17 MPa. Following treatment, the compression stress ranged from 7 to 13.4 MPa, indicating that the exposure to a high pH solution facilitates the densification process. However, a reduction in flexural properties (MOR, LOP, and MOE) was observed on the alkali-treated samples after a three-point bending test. Physical properties (water absorption and thickness swelling) were not altered after delignification. These findings demonstrate that the direct application of a densification process optimized for natural bamboo is not fully effective for chemically modified bamboo, highlighting the need for adjustments. Delignified bamboo showed an increase in free space after chemical treatment, which should be further densified under higher degrees. Full article

This study aims to improve the performance of wood–plastic composites (WPCs) composed of cotton stalk powder and residual film particles. Additionally, it aims to promote the efficient utilization of cotton stalk biochar. The composites were prepared using modified cotton stalk biochar and xylem powder as the matrix, maleic anhydride grafted high-density polyethylene (MA-HDPE) as the coupling agent, and polyethylene (PE) residual film particles as the filler. The WPCs were fabricated through melt blending using a twin-screw extruder. Mechanical properties were evaluated using a universal testing machine and texture analyzer, Shore D hardness was measured using a durometer, and microstructure was analyzed using a high-resolution digital optical microscope. A systematic investigation was conducted on the effect of biochar content on material properties. The results indicated that modified biochar significantly enhanced the mechanical and thermal properties of the WPCs. At a biochar content of 80%, the material achieved optimal performance, with a hardness of 57.625 HD, a bending strength of 463.159 MPa, and a tensile strength of 13.288 MPa. Additionally, thermal conductivity and thermal diffusivity decreased to 0.174 W/(m·K) and 0.220 mm²/s, respectively, indicating improved thermal insulation properties. This research provides a novel approach for the high-value utilization of cotton stalks and residual films, offering a potential solution to reduce agricultural waste pollution in Xinjiang and contributing to the development of low-cost and high-performance WPCs with wide-ranging applications. Full article

Wood, as a natural and renewable resource, plays a crucial role in industrial production and daily life. Lignin, as one of the three major components of the plant cell secondary wall, plays a key role in conferring mechanical strength and enhancing stress resistance. The caffeic acid-O-methyltransferase (COMT) family of oxygen-methyltransferases is a core regulatory node in the downstream pathway of lignin biosynthesis. Here, our report shows that caffeic acid-O-methyltransferase 2 (COMT2) exhibits high conservation across several species. Tissue expression analysis reveals that COMT2 is specifically highly expressed in the secondary xylem of Populus tomentosa stems. We demonstrated that the specific overexpression of COMT2 in fiber cells of Populus tomentosa led to a significant increase in plant height, stem diameter, internode number, and stem dry weight. Furthermore, we found that the specific overexpression of COMT2 in fiber cells promotes xylem differentiation, lignin accumulation, and the thickening of the secondary cell wall (SCW) in fiber cells. Our results indicate that key downstream lignin biosynthesis enzyme genes are upregulated in transgenic plants. Additionally, mechanical properties of stem bending resistance, puncture resistance, and compressive strength in the transgenic lines are significantly improved. Moreover, we further created the DUFpro:COMT2 transgenic lines of Populus deltoides × Populus. euramericana cv ‘Nanlin895’ to verify the functional conservation of COMT2 in closely related poplar species. The DUFpro:COMT2 Populus deltoides × Populus. euramericana cv ‘Nanlin895’ transgenic lines exhibited phenotypes similar to those observed in the P. tomentosa transgenic plants, which showed enhanced growth, increased lignin accumulation, and greater wood strength. Overall, the specific overexpression of the caffeic acid O-methyltransferase gene COMT2 in poplar stem fiber cells has enhanced the wood biomass, wood properties, and mechanical strength of poplar stems. Full article

The corrosion-induced strength degradation of steel nails poses a critical challenge to the structural integrity of timber connection joints, particularly in hygrothermal environments. Compressed wood nails exhibit hygroscopic expansion characteristics, demonstrating their potential as a sustainable alternative to steel nails in structural connections. However, systematic investigations on their shear performance under cyclic hygrothermal conditions remain limited. This study comparatively analyzed the shear behavior evolution of compressed wood nail and galvanized steel nail connections under wet-dry cycles. Distinct failure mechanisms were observed: wood nail connections exhibited characteristic brittle fracture patterns, whereas steel nail connections demonstrated ductile failure through pull-out deformation with nail bending. Notably, compressed wood nails displayed superior environmental stability, with significantly lower degradation rates in terms of load-bearing capacity (2.8% vs. 22.3%) and stiffness (16.3% vs. 38.0%) than their steel counterparts under identical hygrothermal exposure. These findings provide critical design references and data support for implementing wood-based fasteners in moisture-prone engineering applications. Full article