European Journal of Wood and Wood Products最新文献

Oriented strand board (OSB) is an important engineered wood product. The physical and mechanical properties of OSB can be adjusted by optimizing its structural characteristics to fulfill the different application fields. Eight types of boards were produced in the lab in terms of different structural characteristics, including the thickness of surface/core layer, strand’s size and strand’s thickness. Large strands are used in the top/bottom layer of all types of boards. Their physical and mechanical properties were investigated. The results show that the density of the core layer increases with decreasing the size of strands. The orientation angle difference between large (length 150 ± 5 mm×width 35 ± 5) mm) and medium (length 75 ± 5 mm × width 20 ± 2 mm) strands is slight. The modulus of elasticity (MOE) and modulus of rupture (MOR) of all types of boards along major axis are higher than 6500 MPa and 45 MPa respectively. Small strands (length 2 ± 1 mm × width 1 ± 0.5 mm) in the core layer significantly decrease the MOR along the major axis. The MOE and MOR along the minor axis decrease because of small strands in the core layer and thin core layer. Small strands in the core layer are conducive to enhancing the internal bond strength (IB), while thin strands in top/bottom layer significantly decrease the IB. Small strands in the core layer significantly decrease the 24 h thickness swelling. A thin core layer indicates to low screw holding capability in the side face of boards. The outputs of this study contribute to optimizing the production and application strategies of OSB.

The timber construction industry mainly uses softwood as structural products, owing to the slenderness of the trees and rather homogeneous nature of the timber, which makes it easier and more cost-effective to process compared to hardwood. By using narrower and shorter components than for softwood, it might be technically and economically possible to produce finger-jointed, edge-glued oak laminations to be used in glued laminated products. This study proposes to explore the impact of the shorter size of components and thus greater heterogeneity of oak edge-glued laminations on their structural properties. Homogenizing the elastic modulus of the components of the laminations through preliminary sorting appeared to greatly improve the strength of the edge-glued laminations, whereas the sole strength grading with no further control of elastic modulus variability could lead to low strengths with disadvantageous system effect. The local evaluation of the ratio between the lowest and highest MoE values of sub-boards in parallel across the lamination width proved to be correlated to tensile strength, with a coefficient of determination of (R^2) = 0.30. Moreover, homogenizing the elastic modulus of the laminations led to strengths corresponding to system factor values (k_{sys}) exceeding 1.1, as recommended by the standard. A better control of variability of the mechanical properties of hardwood products, seems offering a pathway to more efficient utilization of the hardwood resource.

This study presents an experimental and numerical investigation of the load-bearing mechanism and mechanical performance of traditional Dou-Gong timber brackets under eccentric compression. Two typical construction types, i.e., Jixinzao brackets (with continuous transverse arms) and Touxinzao brackets (with omitted transverse arms), were selected, and comparative analyses were carried out under different eccentricity ratios (e = 0, 0.15, 0.30). The results show that in Jixinzao brackets, the continuous transverse arms form a distributed load-transfer network, concentrating damage in core components including the Lu-Dou, Nidao-Gong, and Hua-Gong. In contrast, Touxinzao brackets exhibit multi-node shear failure and torsional instability due to detoured load paths. Eccentric loading significantly reduces the bearing capacity of both Dou-Gong brackets and accelerates stiffness degradation. Both types of brackets display good ductility under axial compression (ductility coefficient > 2.4), with small decline under eccentric loading. Component level analysis further reveals that continuous transverse arms play a critical role in suppressing sliding, which enhances overall stability. Numerical models developed using ABAQUS showed good agreement with the experimental results and can be used for mechanical evaluation and parametric analysis under eccentric effects. Overall, this research provides a valuable basis and engineering reference for the modern utilisation, structural assessment, and design of traditional Dou-Gong systems.

The differential swelling caused by moisture absorption generates swelling stress within the wood; however, there are few studies on this swelling-induced stress. To explore the rheological characteristics induced by swelling, North American red alder wood treated by heat treatment (HT) and conventionally kiln-dried (CKD) was immersed in water at 70 °C and 90 °C. The water uptake rate, moisture content (MC) distribution, tangential and radial swelling ratios and strains were investigated. The results showed that the high initial water uptake rates of HT and CKD wood decreased at an MC of 6% (70 °C) and 12% (90 °C). HT slows the wood’s water uptake by 17.3–28%. For both HT and CKD wood, water uptake resulted in higher surface MCs than core MCs. However, ANOVA indicated no significant gradient differences between or within groups. Although HT slows the uptake rate, it does not affect the gradients in both woods. The radial swelling ratios of both woods were greater than the tangential ones until the MC reached 22.5%, but HT does not affect the wood’s swelling ratio during water uptake. The swelling strain generally increases with increasing MC, reaching a maximum of 0.0633. The elastic strain and viscoelastic creep strain were similar, yet the latter exceeded the former, with a maximum difference of 0.0157. Mechano-sorptive creep strain varies according to layer, group, MC, and temperature. The mean strains are 0.0422 and 0.0455 at 70 °C and 90 °C respectively. HT does not affect the water-uptake-induced strains of swelling, elastic, and viscoelastic, but has a significant effect on the mechano-sorptive creep strain of wood when the MC is higher than 22.5%.

The present study deals with the experimental investigation of the effect of the Sikadur-32 LP surface coating on the durability of borax-boric acid treated bamboo strips for up to a period of 125 days at ambient temperature in alkaline and water environments using the constant immersion test. About four hundred specimens were tested in five categories: non-coated ambient, non-coated alkaline, coated alkaline, non-coated water and coated water conditions, in which half of them were nodal and the remaining half were internodal. The tensile strength and modulus of elasticity were measured after 30, 70, and 125 days. Results revealed a progressive degradation in all cases, with non-coated samples retaining only 59–73% tensile strength and 53–58% modulus after 125 days. The coated samples demonstrated improved performance, retaining 69–81% tensile strength and 67–71% modulus. In all the cases, the internodal samples showed a 7–11% improvement in the strength retention compared to nodal samples. XRD confirmed crystallinity loss in non-coated bamboo after alkaline exposure, while the coating preserved the cellulose structure. FTIR indicated reduced lignin degradation in coated samples, and SEM revealed severe deterioration of parenchyma cells in samples immersed in the alkaline and water solutions, whereas samples in the ambient conditions retained their structural integrity. These findings highlight the effectiveness of Sikadur-32 LP coating on chemically treated bamboo in aggressive environments, making it a promising protective strategy for sustainable bamboo reinforcement applications

Lightweight frame walls are widely utilized in construction due to their lightweight design, ease of installation, and cost-effectiveness. However, increasing demand for privacy and comfort necessitates improvements in their airborne sound and thermal insulation performance. This study addresses critical challenges such as “acoustic/thermal bridge”, low-frequency resonance, and high-frequency coincidence effects. By integrating advanced materials and innovative structural designs, a novel dual-cavity wall system is introduced to enhance performance. The weighted sound insulation index (R_w) was calculated and validated through COMSOL Multiphysics simulations and theoretical thermal insulation calculations. The results demonstrate, compared to traditional lightweight wood frame walls, the R_w of midply wood walls and light steel frame (LSF) walls increased from 43 to 52 dB, elevating the sound insulation level from 4 to 7. The heat transfer coefficient of the midply wood wall decreased to 0.63 W·m^− 2·K^− 1 after insulation measures, while the “thermal bridge” effect in LSF walls was substantially reduced. Simulation and theoretical predictions showed good agreement with experimental measurements, validating the proposed enhancements. This study offers a scalable, cost-effective solution for modern construction, tackling urban noise and energy efficiency. It advances sustainable building solutions, aiding global carbon reduction and indoor environmental quality improvement.

Eucalyptus pellita is cultivated for pulpwood in tropical and subtropical regions but remains underutilised for structural applications, particularly in dry tropical environments. Compared to well-studied species such as Eucalyptus grandis and Eucalyptus globulus, its potential in engineered wood products is poorly understood. As plantation industries seek to diversify products and increase wood value, understanding the structural suitability of E. pellita hybrids is critical. This study evaluated the performance of E. pellita and its F1 and backcross hybrids across two dry tropical sites, spanning log quality, product recovery, structural properties, and genetic associations. Billets were assessed for form, diameter, and defects. Sawing and peeling trials quantified recovery rates and defects. Laminated veneer lumber (LVL) was fabricated from hybrid veneers and tested for density, modulus of elasticity (MOE), modulus of rupture (MOR), and bond quality. The E. pellita x Eucalyptus brassiana hybrid achieved highest recoveries among the materials tested (sawn board recovery up to 49.2%; green veneer recovery up to 83.6%). The highest-performing LVL (layup 3) from this hybrid achieved an MOE of 18.8 GPa and MOR of 139 MPa. Genetic analysis using a targeted panel of ~ 5500 single nucleotide polymorphism (SNP) markers identified significant associations above the –log₁₀(p) = 1.30 threshold for end split (SNP1358), knot diameter (SNP3201), and heartwood proportion (SNP2187). Although statistical power was limited by sample size, these findings highlight the potential of E. pellita hybrids for structural applications and demonstrate the value of integrating phenotypic and molecular data to support tropical hardwood breeding and utilisation strategies.

Robinia pseudoacacia L. has a valuable wood due to its natural durability and resistance to decay and external environments. This durability is attributed to its high content of extractives and the amount of tyloses in earlywood vessels. Given the widespread occurrence of black locust across Hungary, the wood chemical components may differ depending on site growth conditions. This research investigated the chemical extractives and color parameters of wood from Robinia pseudoacacia L. from different counties and growth conditions in Hungary. The relationship between chemical extractives and color based on the CIElab system was also analysed. The results indicated that both counties and growth conditions showed significant variations in chemical extractives and color parameters. The counties of Vas and Győr-Moson-Sopron exhibited the highest total contents of extractives, polyphenol, antioxidant capacity and intense lightness. Compatible outcomes were recorded under poor growth condition mixed species. Lightness was significantly associated with extractives from methanol-water and total phenol contents with lightness. While the extractive from the cyclohexane-ethanol solvent system was linked with all color parameters. Subsequent research will investigate the impact of extractives on wood durability under different locations and growth conditions.

Wooden dowels transfer load in timber connections through combined mechanisms, including longitudinal shear, bending and embedment. Shear properties parallel to the grain are essential for mechanics-based stiffness models and numerical simulations of wooden dowel connections, yet no standardised method exists for their determination. This study addresses this gap by investigating and optimising shear-testing methods for wooden dowels using experimental and numerical approaches. This study compares four shear-testing approaches for determining the shear strength of wooden dowels using a compression test setup, supported by experimental work, numerical modelling and fundamental mechanics. Parametric FEA in LS-DYNA was conducted to optimise specimen geometry, and the effects of notch-end shape, notch width, failure-plane height and specimen length on stress distribution and failure mode were assessed. Among the four methods, the 45° double-notched specimen was identified as the most effective for generating an approximately pure shear state. Digital Image Correlation (DIC) was used to evaluate five strain-gauge areas and five strain-calculation methods. The validated configuration was then used for further shear testing. The study shows that all optimised specimen configurations produce comparable shear strengths parallel to the grain, indicating the potential suitability of these methods for wooden-dowel shear testing. However, notch shape, notch width, failure-plane height and specimen length must be properly optimised to ensure shear-dominated failure. Smaller virtual strain-gauge areas, particularly the thin-line area method between notch tips, provide more representative shear-strain measurements and shear-modulus values. Numerical modelling using MAT-143 successfully captured the post-peak softening behaviour and supports its use for shear simulations.

Brittleheart, also known as compression failure, is a widespread phenomenon observed in numerous tropical wood species, significantly diminishing their strength properties. According to strength grading standards such as BS 5756, NEN 5493 and EN 16,737, timber exhibiting brittleheart characteristics must be rejected. Oftentimes brittleheart remains undetectable on the outer surface and cross-section of sawn timber. This study focuses on qualitatively characterizing compression failures in tropical hardwood and its mechanical properties. In this context, various non-destructive detection methods were explored. Five grades of compression failures were characterized based on the deformation and displacement of wood tissue. Results demonstrate that CT-scanning shows promising as a technique for detecting these five defined grades. Quantitative assessments of brittleheart on the mechanical properties were conducted to determine bending strength (f_m) and modulus of elasticity (E_m). Multiple regression models were developed to predict the bending strength with a highest coefficient of determination (R²) of 0.778 and a relatively high SEE of 17 N/mm².