• Continuous quality and reliability improvement of computers as well as their widespread application in design of furniture industry encourage the elaboration of optimization algorithms

The present study examined the bending moment capacity and rigidity of T-type out-of-plane furniture joints and investigated the effects of heat treatment, wood species, and joint type factors on these joints. Heat treatment method clearly decreased the modulus of rupture (MOR) and the modulus of elasticity (MOE) of selected wood species. The bending strength of wood samples was reduced after the heat treatment, decreasing with increased loss of mass. For the heat-treated T-type joints, maximum bending strength values were obtained with Iroko (Chlorophora excelsa) for both mortise and tenon (MT) joints and blind MT (BMT) joints. The lowest reduction in bending strength was observed in Ash (Fraxinus excelsior L.) constructed with MT joints and with BMT joints. In general, the BMT joint had higher bending strength than MT joints. The best rigidity constant (7.21) was obtained with control Iroko BMT joints, while the worst rigidity constant (15.10) was obtained with control Oriental spruce (Picea orientalis L.) MT joints. In terms of heat-treated samples, the best rigidity constant (7.59) was obtained with Black pine (Pinus nigra L.) MT joints, while the worst rigidity constant (14.01) was obtained with Oriental spruce BMT joints. The maximum performance in joint stiffness was determined for Iroko sample BMT joints and Iroko MT joints. Lowest reduction in joint stiffness was observed in Scotch pine MT joints and Ash BMT joints. Heat treatment, wood type, and joint type had a significant effect on the bending strength of T-type MT post-rail joints. BMT joints produced from heat-treated Iroko wood can be considered as the most durable T-type joint for outdoor sitting furniture construction.

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The friction welding method has been an effective criterion in determining the mechanical performance of wood joints in wood industry applications compared to traditional methods. Although it is used in structural applications, joints from linear vibration are quite sensitive to water. In this study, the water resistance of the heat-treated woods, iroko (Chlorophora excelsa), ash (Fraxinus excelsior L.), tulip wood (Liriodendron tulipifera) and ayous (Triplochiton scleroxylon), were investigated by friction linear welding. The weld line density profiles were examined. The resistance of heat-treated welded wood joints to water remarkably decreased compared to the control sample, depending on water immersion time. The highest shear strength loss was found in tulip wood (60% to 65%) and the lowest shear strength loss was found in ash wood (3%) for the heat-treated group and in Iroko wood (17%) for the control. The heat-treated samples increased in density with welding but had a slightly lower density than the control group. According to the TGA results, it was found that the thermal degradation of untreated welded woods was lower than that of heat-treated welded woods. This difference could be due to the chemical constituents of hardwood and tropical wood. X-ray computed tomography (CT-scanning) is feasible and usable for welding line density change.

Učinci lignoceluloznih punila na mehanička, morfološka i toplinska svojstva drvnoplastičnih kompozita Received -prispjelo: 2. 12. 2016. Accepted -prihvaćeno: 30. 8. 2017 630*864.26 doi:10.5552/drind.2017 prove its strength. Natural fi bers can be used to reinforce rather than fi ll a plastic, which increases the strength as well as stiffness. Wood and other lignocellulosic fi bers typically have higher particle sizes than those of wood fl our. Furthermore, the aspect ratio of the fi ber can be increased. At a critical fi ber length, stress is transferred from the matrix to the fi ber, resulting in a stronger composite. Stress is effi ciently transferred only if the bond between the matrix and fi ber is good (Oswald and Menges, 1995). The aim of this study was to determine the usability of waste wood fl our and fi bers from particleboard and fi berboard in the manufacturing process of wood plastic composites. Also, some physical, mechanical and morphological properties of wood plastic composites were examined. Original scientifi c paper • Izvorni znanstveni rad

Interpolation and internal painting are one of the basic approaches in image internal painting, which is used to eliminate undesirable parts that occur in digital images or to enhance faulty parts. This study was designed to compare the interpolation algorithms used in image inpainting in the literature. Errors and noise generated on the colour and grayscale formats of some of the commonly used standard images in the literature were corrected by using Cubic, Kriging, Radial based function and High dimensional model representation approaches and the results were compared using standard image comparison criteria, namely, PSNR (peak signalto-noise ratio), SSIM (Structural SIMilarity), Mean Square Error (MSE). According to the results obtained from the study, the absolute superiority of the methods against each other was not observed. However, Kriging and RBF interpolation give better results both for numerical data and visual evaluation for image in-painting problems with large area losses.

The aim of this study was to investigate the effect of heat‐treated lignocellulosic filler on the surface characteristics and decay resistance of the wood flour/styrene maleic anhydride (SMA) composites. In this study, heat treatment was conducted at 212°C for 8 hours. Test specimens were prepared by injection molding at 220°C. Weathering tests were performed by cycles of UV‐light irradiation for 8 hours, water spray for 15 minutes, and then conditioning for 3.45 hours in an accelerated weathering test cycle chamber. Heat‐treated wood flour/SMA composites were evaluated for color changes, and attenuated total reflectance Fourier transform infrared (FTIR) spectroscopy was used to analyze chemical changes on the sample surfaces. The wood decay tests were performed of white rot fungus, Trametes versicolor (L.: Fr.) Pilat was based on mini‐block specimens on 48% malt extract agar in petri dishes. The study showed that color changes occurred when heat‐treated filler rate is increased in this material. Therefore, materials in 10% filler rate show lower color changes than other variation. As a result of the FTIR analysis, the addition of wood filler into the SMA causes changes in the chemical structure. In addition, the increase in wood filler reduced the resistance to weathering. Decay results showed that thermally modified wood has lower mass loss caused by fungal attack than untreated wood material. The weight loss decreases with the increase in wood flour rate expect 10%T and 10%UT in all composites.

Aim of study: In this study, it was aimed to establish and optimize a production process for engineering thermoplastic composites based on heat treated wood fillers and SMA copolymer. Material and Methods: As wood material, pine wood (Pinus strobus L.), and as a thermoplastic copolymer material, Styrene Maleic Anhydride (SMA) copolymer were used in this study. Heat treatment was conducted at 212°C for 8 h in an attempt to improve the durability of the wood furnish and the wood flour and SMA compounds were extruded and granulated using a lab-scale grinder. Physical test, mechanical test and morphological tests were calculated. Main results: The results showed that the highest tensile strength was in the 30 wt.% wood flour/SMA and it has been seen that the positive effect on FMOE,TMOE of heat treated wood flour/SMA. Weak interfacial bonding was observed between the polymer and wood filler from the SEM images of the fractured surfaces of wood flour/SMA composites. Research highlights: The results from this research indicated the compatibility of the SMA copolymer with the wood flour and the changes in the mechanical strength of the material. Due to limited heat treated wood thermoplastic composite usage in the field of wood engineering, there is a need for more extensive work in the future.