•Addition of nanocellulose (CNF and CNC) to PVAc adhesive improved the elastic stiffness of the joints as well as the bond quality.•The addition of nanocellulose stabilized the bond line against ...cyclic moisture exposure and thereby improved the mechanical properties.•The bonding ability of CNF and CNC reinforced PVAc adhesives is evident from the increased proportion of wood failure.•If CNF and CNC dispersion in PVAc can be achieved without dilution of the adhesive, then the reinforcing ability of CNF and CNC can be better realized.
Cellulose nanofiber (CNF) and cellulose nanocrystals (CNC) are strong bio-based materials and have great potential in a reinforcement of the polymeric matrix. This study presents the effect of nanocellulose (CNF and CNC) reinforcement of polyvinyl acetate (PVAc) adhesive. Adhesive formulations with three different concentrations (0.5%, 1%, and 2% w/w) of nanocellulose were prepared by dispersing them in water and mixing the suspension with PVAc adhesive; the other percentages are omitted due to obvious adverse effect. The reinforced adhesive was then used to glue spruce (Picea abies L) and beech (Fagus sylvatica) wood joints to determine joint stiffness and shear strength under static load. Samples were tested at 12% moisture content and after cyclic moisture exposure. Bond line morphology was studied by SEM. FTIR analysis was performed to see the molecular interaction between nanocellulose and PVAc. The addition of nanocellulose to PVAc adhesive significantly improved the elastic stiffness and shear strength of the joints. Optimum elastic stiffness and shear strength values were achieved with a 1% addition of nanocellulose. The general trends are found to be valid for various kind of CNF and CNC.
Automatic species identification has the potential to improve the efficacy and automation of wood processing systems significantly. Recent advances in deep learning allowed for the automation of many ...previously difficult tasks, and in this paper, we investigate the feasibility of using deep convolutional neural networks (CNNs) for hardwood lumber identification. In particular, two highly effective CNNs (ResNet-50 and DenseNet-121) as well as lightweight MobileNet-V2 were tested. Overall, 98.2% accuracy was achieved for 11 common hardwood species classification tasks.
This paper deals with research on the impact of material properties (material thickness and type) on stress/strain curves of the layered materials based on hard and soft wood during bending. ...Reference curves, obtained for the bending of real samples, were the base for the simulation. Subsequently, the recorded curves were imported into SolidWorks application, where they served as the data source for the simulation. The results, as well as model analysis of two-layer materials, have proven that the bendability is better for the composition with soft material in the bottom layer. This can be explained by the fact that the soft material under tensile strength shows greater deflections than the hard one before the breaking. For three-layer compositions, similar behavior can be concluded. This part did not deal with connection among the layers. The paper gives a possibility to predict the behavior of layered materials if the characteristics of its layers are known.
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•Combinations of hard and soft wood material with various thicknesses were produced.•Simulations of various compositions for layered materials were realized.•The designed combinations were tested under bending.•Bendability coefficient depended on the layers position and thickness in the composition.•Compositions with soft material placed in the bottom layer had better bendability.
•The addition of nanocellulose in PUR adhesive improved spruce wood joints' elastic stiffness and shear strength at 12% moisture and after moisture cycling condition (8–19%).•In beech wood joints ...there is no significant difference after the addition of CNF and CNC in PUR adhesive.•Among the three (0.5%, 1%, and 2%) concentrations of nanocellulose (CNF and CNC) reinforcement, 1% addition was found to be the optimum for elastic stiffness and shear strength.•SEM analysis shows the morphology studies, and nanocellulose reinforced adhesive shows a relative improvement on the bond-line by the good dispersion of CNF and CNC addition to PUR adhesive.•The DSC study indicated that the glass transition temperature increased of PUR adhesive by the reinforcement of CNF and CNC.
Polyurethane (PUR) adhesive was reinforced with cellulose nanocrystal (CNC) and acetylated cellulose nanofiber (CNF) to enhance its bonding performance. The reinforced adhesive was used to prepare lap joints using spruce and beech wood. Cyclic moisture exposure was carried out to assess the effect of moisture variation on the bond performance. Elastic modulus and shear strength were determined to ascertain the bonding behavior of adhesives. Reinforcement of PUR with nanocellulose significantly improved (33%) the elastic modulus in spruce wood while the improvement was only marginal (12%) in beech wood. Cyclic moisture exposure reduced the elastic modulus of CNC reinforced PUR in both the species, while the value increased by 5% for 0.5% CNF reinforced PUR joints. Reinforcement of PUR with nanocellulose significantly improved the shear strength. The improvent was more in spruce (45%) as compared to beech wood (35%). Moisture exposure caused a significant improvement in the shear strength of pure and reinforced PUR bonded joints, however, the values decreased for spruce wood except for 0.5% CNF loading where it was marginally higher. SEM micrographs revealed improved bond line with nanocellulose reinforcement in both the wood species. The glass transition temperature of PUR adhesive slightly decreased due nanocellulose reinforcement.
Tests were carried out to determine the bending moment capacities of L-shaped mortise and tenon furniture joints under both compression and tension loadings. The effects of wood species (Turkish ...beech and Scotch pine), adhesive type (polyvinylacetate and polyurethane), and tenon size (width and length) on the static bending moment capacity of joints under the same loading conditions were investigated. The results of the tests indicated that the moment capacity increased as either tenon width or length increased. The results also indicated that tenon length had a greater effect on the moment capacity than tenon width. In both compression and tension tests, Turkish beech joints were stronger than Scotch pine joints, and PU joints were stronger than PVA joints. An empirically derived expression was developed to estimate the average ultimate bending moment capacity of joints under compression and tension loads as functions of the wood species, the adhesive type, and the tenon size.
Tests were conducted to determine the bending moment capacity of 215 red oak and 140 white oak T-shaped rectangular mortise and tenon joints. Rails measured 22.2 mm by 63.5 mm in cross section; ...tenons measured 32 mm in length by 38 mm in height by 9.5 mm in thickness. Specimens were assembled with a 40% solid content polyvinyl acetate adhesive. The average bending moment capacity of the red oak specimens was 353 Nm with a standard deviation of 48 Nm; in the white oak specimens, it was 358 Nm with a standard deviation of 62 Nm. The lower tolerance limits of the red oak specimens at the 75|75, 90|75, 75|90, 90|90, and 95|95 confidence|proportion levels were 318, 316, 289, 286, and 266 Nm, respectively, whereas in white oak specimens, the values were 314, 308, 273, 268, and 240 Nm, respectively. Overall, the results indicated that the use of statistical lower tolerance limits procedures provide a systematic means of relating standard deviations to mean values in determining reasonable design values for the moment capacity of the joints. Conclusions were not reached concerning which confidence|proportion level might be best suited for determining reasonable design values for furniture joints, but the results did illustrate the consequences of a given choice.
The relationship between the static front to back loading capacity of chairs and the moment capacities of the joints used in their side frames was investigated. The secondary purpose of the study was ...to determine the effect of tenon sizes on front to back loading capacity of chairs. The moment capacities of round edge mortise and tenon L-shaped and T-shaped joints constructed of Turkish beech (Fagus orientalis L.) with cross sections and tenon sizes identical to those used in the chairs were first determined. Tenons varied from 30, 40, and 50 mm in width and 30, 40, and 50 mm in length. Joints were assembled with 65% solid polyvinylacetate (PVAc) adhesives. Front to back loading tests were then performed on the chairs according to the method adopted by the American Library Association (ALA). The results indicated that front to back loading capacity increases as either tenon width or length increases. Highest joint moment capacities were obtained when L-shaped joints were constructed with 50 mm wide by 50 mm long tenons and T-shaped joints were constructed with 40 mm wide by 50 mm long tenons. Finally, the strength of chairs could be reasonably predicted from the strength of joints.
The lower tolerance limits (LTLs) for two-pin moment-resisting dowel joints, constructed of red oak and white oak, were estimated. Dowel joints are widely used in furniture manufacturing, especially ...for tables and chairs. Despite numerous studies to determine the strength capacities of dowel joints, their design values have not been established. For this purpose, T-shaped edgewise dowel joints were constructed to determine their ultimate failure load capacity levels. In tolerance analysis, the k-tolerance factor changes depending on sample sizes and confidence/proportion levels. Therefore, sample sizes were determined using a modified Faulkenberry-Week method for a univariate normally distributed data set created for a pilot study, which had 30 specimens. At least 215 specimens were required to make tolerance analyses at the 99/99 confidence/proportion level. Accordingly, 220 specimens were constructed. The LTL values were obtained at the 75/75, 90/75, 75/90, 90/90, 95/90, 90/95, 95/95, 99/95, 95/99, and 99/99 confidence/proportion levels to estimate reasonable design values. The results of the study indicated that the LTL method provides a sound design value estimate for dowel joints used in furniture frames.
As utilized technical products, durable wood furniture plays an important role in a future circular economy (CE). However, contemporary CE literature predominantly focuses on wood's biochemical ...properties and its potential as a consumable material within the bio‐cycle. This perspective prevents meaningful consideration of CE strategies for the wood products sector, particularly for value‐retention processes (VRPs), including reuse, repair, and refurbishment. We adapt and apply the VRP model introduced by the UN International Resource Panel (IRP) to wood furniture products to quantify select environmental benefits made possible through cascading‐use, via VRPs (vs. new manufacturing). Unlike traditional life cycle assessment (LCA), this model accounts for impacts incurred and avoided through product life‐extension and VRPs, relative to conventional systems of new manufacturing, disposal, and replacement. Three case studies of wood‐based chairs are conducted to demonstrate this new application of the VRP model to compare the relative environmental impacts associated with wood furniture that is diverted to cascading‐use, prior to recycling. In collaboration with industry partners, new material requirements (kg/unit), energy requirements (kWh/unit), emissions (kg CO2‐e./unit), and waste generation (kg/unit) were calculated for newly manufactured chairs (OEM new) and subsequent cascading‐use via reuse, repair, and refurbishment. The differing degrees of environmental impact avoidance and material efficiency are presented for each case study product and VRP, to provoke discussion and future research regarding the effective and optimal utilization of technical, durable wooden furniture within a CE.
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