Wood surface defect detection poses challenges due to the diverse range of defects, making accurate localization and identification difficult. In this study, we introduce an enhanced approach for ...detecting flaws on wood surfaces by leveraging an augmented version of the YOLOv8s algorithm. To improve the focus on problematic target qualities, we initially constructed a HAM (hybrid attention module) structure within the Backbone. This structure incorporates spatial and channel attention techniques, enhancing the ability to identify defects. Additionally, we enhance the feature fusion capabilities by augmenting the expansion convolution module, reducing information loss during the connection with the Neck network. This augmentation improves the target receptive field, ensuring critical information preservation for effective diagnosis of wood surface defects. Furthermore, we introduce ghost convolution to enhance feature expression while minimizing the number of parameters. This approach optimizes the model's overall performance. Through extensive testing, our proposed GH-YOLOv8s model demonstrates accurate detection of five distinct types of wood surface defects, including defect types such as Live Knot, Dead Knot, Resin, Knot with crack, and Crack, achieving a mean average precision (mAP) of 98.4%. This performance surpasses the original model by 2.0% and maintains a high FPS (Frames Per Second) rate of 163.9, this means it can achieve efficient object detection in real-time scenarios. Moreover, our approach outperforms commonly used target detection methods, establishing its superiority in wood surface defect detection.
In this study, the aminated cellulose (AC) and branched epoxy (BE) were prepared. After the chlorination and amination of microcrystalline cellulose, its hydroxyl groups were replaced by amino ...groups. Through thiol-ene click chemical reaction, a branched epoxy was synthesized from trithiocyanuric acid and glycidyl methacrylate. A covalent bond network was formed by epoxy groups crosslinked with amino groups on AC. Furthermore, a new concept of chemical wood bonding interface was adopted on this basis. Due to the hydrolytic condensation of 3-aminopropyltriethoxysilane, the amino groups were grafted onto the surface of wood skeleton for increasing the reactive site and enhancing the synergistic effect between adhesive and interface. By constructing the chemical crosslinking network of “amino-epoxy-amino”, the bonding between adhesive and wood interface got obvious improvement. Compared with the plywood made by natural wood, the dry strength of the plywood prepared by activated wood was increased from 1.46 MPa to 2.19 MPa, which increased by 50%, and the strength of soaking in 63
o
C water for 3 h was increased from 0.36 MPa to 2.20 MPa, and the wet strength of boiling water increased from 0 to 0.83 MPa. FT–IR and XPS were used to prove the chemical covalent cross-linking reaction between adhesive and activated wood surface.
Graphical abstract
The preparation of AC-BE adhesive and bonding with activated wood surafce
The technical assessment of wooden elements is the primary step in their repair and reinforcement design. Normative requirements currently mandate additional tests, including semi-destructive ones, ...beyond traditional visual assessment. Despite the growing feasibility of semi-destructive tests for qualitative assessments, there remains a paucity of data enabling quantitative assessments. This study investigated the hardness of structural timber, specifically pine, spruce, and fir, from Central Europe using sclerometric methods. The outcomes of these tests were compared with those of conventional destructive tests and correlational relationships were established. A strong correlation was found between the sclerometric tests and density (r = 0.62 ÷ 0.82), while a range of strong to moderate correlations was found (r = 0.40 ÷ 0.70) for mechanical characteristics (bending and compressive strength). The correlation strength varied among different wood species, with the strongest for pine and the weakest for spruce. All established relationships were compiled into 40 functions to facilitate their future utilization in quantitative assessments during the technical evaluation of wooden objects. The study also examined the influence of wood defects on the derived correlations by considering the knot index. Sclerometric methods accurately reflect the physico-mechanical properties of elements with a small or medium defect content. However, for wood with a high proportion of defects (knots), the correlations are very weak (r = 0.23 ÷ 0.52, including statistically insignificant results). This research offers new insights into the potential of semi-destructive methods in the structural evaluation of wooden elements, highlighting the need to account for wood species and defect content.
This article aims to investigate the contact characteristics of mortise and tenon (M&T) joints in the traditional timber structures. In particular, the normal embedded compressive contact between ...contact surfaces of M&T joint was investigated. Based on basic contact theory and contact characteristics between mortise and tenon, a normal elasto-plastic contact model, which can reflect the real normal contact behavior of M&T joints in traditional wooden structures, was proposed. Coulomb friction contact was utilized to describe the tangential slipping characteristics of the contact surfaces. Micro-morphology scanning tests of wood samples with different roughness were carried out to determine the parameters involved in the normal contact model. The normal contact model subroutine of M&T joint was compiled by FORTRAN language, implemented into ABAQUS through user-defined interface (UINTER). Then the proposed model was verified by shear tests of wood contact surfaces considering different normal pressures. Finally, a finite element model (FEM) of straight tenon joint subjected to cyclic reversed loading, based on the proposed normal elasto-plastic contact model, was developed, and a FEM considering normal “hard contact” between the contact surfaces, was also performed. The simulation results were validated by the experimental results. Results showed that the user-defined normal elasto-plastic contact FEM was more in line with the actual force state and mechanical behavior of M&T joints, which can more accurately predict the failure modes and simulate the hysteretic behavior of M&T joints, compared to the FEM considering normal “hard contact” of the contact surfaces.
The incorporation of nano-particles into coatings to protect wood against UV light has tremendous potential for improving coating performance. However, the understanding of the mechanisms by which ...these particles function on wood surfaces remains limited. The distribution and potential chemical interactions between alpha Fe
and wood were studied. The ability of different sizes of Fe
particles to intercept various wavelengths of light was assessed using ultraviolet/visible (UV–vis) spectroscopy using TiO
and ZnO particles for comparison. All particles intercepted UV light, but α-Fe
also intercepted a portion of the visible spectrum which might help explain its better performance. Scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM-EDS) analysis of α-Fe
nano-particle distribution on different wood orientations of radiata pine (
D. Don) and shining gum (
) showed that iron particles were uniformly distributed on both pine and shining gum, but provided better UV protection to the more permeable radiata pine surfaces. Characterization of chemical interactions between α-Fe
and isolated lignin and cellulose by Fourier Transform Infrared Spectroscopy (FTIR) suggested substantial interactions between these particles and lignin components, but little interaction with cellulose. The results suggest that the role of nano-particles in the UV protection of wood surface is to intercept and disperse the light energy while interacting with the wood.
The study assessed CNC routing quality on maple and oak samples, using 90º V-Grooving router bits at various milling angles as function of grain orientation: 0°, 15°, 30°, 45°, 60°, 75°, 90°, and ...feed speeds of 3 and 6 m/min at spindle speed of 15,000 rpm. The routing quality was evaluated by roughness parameters for the V flank surfaces and by visual examination for the flanks’ edges. The change in the feed speed had no significant effect for the flanks surface quality of both species, but roughness values were considerable higher for maple samples at 90º and u=3 m/min (Rk = 23.7 µm compared to along the grain, Rk=9.83 µm for u=6 m/min) due to possible processing vibrations. The milling angle as function of grain orientation was significant in the case of oak, as the processing roughness increased with the cutting angle from 0° (Rk=11 to 13 µm) to 60°(Rk =28 to 30 µm). Fuzziness around the earlywood pores of oak was higher for the 6 m/min feed speed. A substantial increase in waviness coinciding with the annual growth areas was measured for crosscut oak samples (Wa = 34.0 µm, compared with Wa =7 .39 µm along the grain). The surface waviness of maple was not sensitive to the variation in the cutting angle or feed speed (Wa was around 3 to 4 µm). For the flank edges, the best visual option was found for cutting along the wood grain and the worst was for 60º, which caused biggest ruptures and especially for the 3 m/min feed speed, for both species.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Wood-based materials are multifunctional green and environmentally friendly natural construction materials, and are widely used in decorative building materials. For this reason, a lot of research ...has been carried out to develop new and innovative wood surface improvements and make wood more appealing through features such as fire-retardancy, hydrophobicity, and antibacterial properties. To improve the performance of wood, more and more attention is being paid to the functioning of the surface. Understanding and mastering technology to improve the surface functionality of wood opens up new possibilities for developing multifunctional and high-performance materials. Examples of these techniques are ion crosslinking modification and coating modification. Researchers have been trying to make wooden surfaces more practical for the past century. This study has gradually gained popularity in the field of wood material science over the last 10 years. This paper provides an experimental reference for research on wood surface functionalization and summarizes the most current advancements in hydrophobic, antibacterial, and flame-retardant research on wood surfaces.
The literature provides very little information about engraving or decorating wood using a laser beam. No study was found that considers the surface roughness of wood after such treatments. This ...paper therefore aimed to find the influence of varying the laser power output and scanning speed of a CO2 laser beam on the surface roughness and colour of beech wood (Fagus sylvatica) for aesthetic applications such as decorative drawing. Laser power outputs from 5.6 to 6.8 W were tested in combination with scanning speeds from 100 to 500 mm/s. The surface roughness was assessed with a robust filter and by following measuring and evaluation recommendations from previous research to reduce the bias from the wood anatomy. The surface roughness measured by a series of roughness parameters (Ra, Rq, Rt, Rk, Rpk, Rvk) and total colour difference DE increased with laser power and decreased with scanning speed. A good correlation was found between surface roughness and wood colour change. Such correlations can be useful for selecting the laser power-scanning speed combinations capable of giving the chosen colour change at a minimum surface roughness.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
The superhydrophobic wood surface was obtained by the combination of spherical-like α-FeOOH particles creating high roughness and OTS monolayer lowing surface energy. The water contact angle of the ...superhydrophobic wood surface reached the maximum of 158 (and the sliding angle was less than 4). Display omitted
► The superhydrophobic wood surface was obtained by a hydrothermal reaction process. ► The wood surface has been transformed from hydrophilic to superhydrophobic. ► Morphology of α-FeOOH particles depends on duration of hydrothermal reaction process. ► The superhydrophobic wood surface showed good stability in air and corrosive liquid. ► The superhydrophobic treatment may contribute to enlarge the use of wood resource.
The superhydrophobic spherical-like α-FeOOH films on the wood surface was obtained from ferric sulfate and urea by a hydrothermal reaction process followed by a self-assembly of Octadecyltrichlorosilane (OTS) monolayer. The microstructure, chemical state and composition of the products were observed by scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and Energy disperse X-ray analysis (EDX). The hydrophobic property of the treated samples was described by static water contact angles (CAs) and sliding water contact angles (SA) measurement. The stability under ambient condition and durability for corrosive liquid of the surperhydrophobic samples were also investigated in this paper. An analytical characterization revealed that the spherical-like α-FeOOH films with micro–nano structure uniformly deposited on the wood surface and OTS molecules combined with α-FeOOH films. The water contact angle of the as-prepared samples reached as high as 158° and the sliding angle was about 4°. The prepared superhydrophobic wood surface still maintained the superhydrophobic property when stored under ambient condition for 3 months or immersed in a sodium hydroxide solution of pH 12 and a hydrochloric acid solution of pH 2 for 2h at room temperature.
In this study, 2
5
(five factors at two-level factorial design) design of experiment was applied to investigate a set of optimal machining parameters to achieve a minimum surface roughness value for
...Abies nordmanniana.
Wood specimens were prepared using different values of spindle speed, feed rate, depth of cut, tool radius, and cutting directions. Average surface roughness
R
z
values were applied using a stylus. The objectives were to: (1) obtain the effective variables of wood surface roughness; (2) analyze which of these factors had an impact on variability in the CNC machining process; (3) evaluate the optimal cutting values within the range of different cutting levels of machining parameters. The results indicate that the design of experiment (DOE) based on the desirability function approach determined the optimal machining parameters successfully, leading to minimum
R
a
compared to the observed value. Minimum surface roughness values of tangential and radial cutting directions were 3.58 and 3.21 µm, respectively.
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