Search

Australia’s hardwood plantation estate is predominantly comprised of Eucalyptus nitens and Eucalyptus globulus, which are mainly being managed to produce woodchips—a low-value commodity export. There is an increasing interest by the timber industry in developing higher-value structural products from the low-grade timber recovered from these plantation resources. In this experimental study, for the first time, the bending performance of nail-laminated timber (NLT) and NLT-concrete composite (NLTC) floor panels constructed of the low-grade, fibre-managed Eucalyptus nitens and Eucalyptus globulus timber was evaluated. The test panels were constructed with various span lengths and cross-sectional configurations and subjected to vibration and four-point bending tests. The results indicated that the modulus of elasticity of the Eucalyptus nitens NLT panels (11,074.6 MPa) was comparable to that of NLT panels made of Eucalyptus globulus (11,203.2 MPa). The modulus of rupture of the Eucalyptus globulus panels was 13.8% higher than that of the Eucalyptus nitens ones. The bending properties of the NLT panels constructed of the two plantation species were superior to those of some commercially important mass laminated timber products reported in the literature. Under the limit state design loads, all the NLT and NLTC panels were still in the linear-elastic range. The fundamental natural vibration frequency values of the test panels were above the recommended minimum range of 8–10 Hz for residential and office floors. The two plantation timber species therefore demonstrated sufficient short-term bending performances to be used in the construction of higher-value structural floor products.

This study tested the machinability of three major timber species grown in Tasmania, Australia, under different resource management schemes: plantation fiber-managed hardwood (Eucalyptus globulus Labill. and Eucalyptus nitens Maiden) and plantation sawlog-managed softwood (Pinus radiata D. Don). P. radiata was used as a control to identify significant differences in machining fibre-managed plantation timber against sawlog-managed plantation timber with numerically controlled computer technology and manually fed timber production techniques. The potential to fabricate architectural interior products such as moldings with plantation fiber-managed hardwood timber that is high in natural features was the focus of this study. Correlations between wood species, variation in moisture content, and density of individual machinability characteristics were analyzed to determine factors impacting the overall quality of plantation wood machinability. Correlations between species and within species groups from the resulting machinability tests are highlighted and discussed. The results indicate that the machinability of sawlog-managed softwood P. radiata is superior in some circumstances to fiber-managed hardwood E. globulus and E. nitens specimens, according to the American Society for Testing and Materials D1666-11.

The use of fast-growing plantation eucalypt (i.e., pulpwood eucalypt) in the construction of high-value structural products has received special attention from the timber industry in Australia and worldwide. There is still, however, a significant lack of knowledge regarding the physical and mechanical properties of the lumber from such plantation resources as they are mainly being managed to produce woodchips. In this study, the physical and mechanical properties of lumber from a 16-year-old pulpwood Eucalyptus nitens H.Deane &amp, Maiden resource from the northeast of Tasmania, Australia was evaluated. The tests were conducted on 318 small wood samples obtained from different logs harvested from the study site. The tested mechanical properties included bending modulus of elasticity (10,377.7 MPa) and modulus of rupture (53 MPa), shear strength parallel (5.5 MPa) and perpendicular to the grain (8.5 MPa), compressive strength parallel (42.8 MPa) and perpendicular to the grain (4.1 MPa), tensile strength perpendicular to the grain (3.4 MPa), impact bending (23.6 J/cm2), cleavage (1.6 kN) and Janka hardness (23.2 MPa). Simple linear regression models were developed using density and moisture content to predict the mechanical properties. The variations in the moisture content after conventional kiln drying within randomly selected samples in each test treatment were not high enough to significantly influence the mechanical properties. A relatively high variation in the density values was observed that showed significant correlations with the changes in the mechanical properties. The presence of knots increased the shear strength both parallel and perpendicular to the grain and significantly decreased the tensile strength of the lumber. The results of this study created a profile of material properties for the pulpwood E. nitens lumber that can be used for numerical modelling of any potential structural product from such a plantation resource.

We studied the effect of loose tenon dimensions on stress and strain distributions in T-shaped mortise and loose tenon (M&LT) furniture joints under uniaxial bending loads, and determined the effects of loose tenon length (30, 45, 60, and 90 mm) and loose tenon thickness (6 and 8 mm) on bending moment capacity of M&LT joints constructed with polyvinyl acetate (PVAc) adhesive. Stress and strain distributions in joint elements were then estimated for each joint using ANSYS finite element (FE) software. The bending moment capacity of joints increased significantly with thickness and length of the tenon. Based on the FE analysis results, under uniaxial bending, the highest shear stress values were obtained in the middle parts of the tenon, while the highest shear elastic strain values were estimated in glue lines between the tenon surfaces and walls of the mortise. Shear stress and shear elastic strain values in joint elements generally increased with tenon dimensions and corresponding bending moment capacities. There was consistency between predicted maximum shear stress values and failure modes of the joints.

We determined the effects of adhesive type and loose tenon dimensions (length and thickness) on bending strength of T-shaped mortise and loose-tenon joints. Polyvinyl acetate (PVAc) and two-component polyurethane (PU) adhesives were used to construct joint specimens. The bending moment capacity of joints increased significantly with increased length and thickness of the loose tenon. Bending moment capacity of joints constructed with PU adhesive was approximately 13% higher than for joints constructed with PVAc adhesive. We developed a predictive equation as a function of adhesive type and loose tenon dimensions to estimate the strength of the joints constructed of oriental beech (Fagus orientalis L.) under uniaxial bending load.

This investigation was conducted to determine the feasibility of using a two-component polyurethane (PUR) adhesive, with special waterproof properties, in constructing wooden structures. We designed and conducted tests to compare the shear strength and adhesion performance of PUR with polyvinyl acetate (PVAc) adhesive on block-shear specimens constructed of oriental beech (Fagus orientalis L.), fir (Abies alba Mill.), poplar (Populus deltoides Bartr.), white oak (Quercus alba L.), sycamore (Platanus orientalis L.) and white walnut (Juglans cinerea L.). The values of the percentage of wood failure were also determined in specimens constructed with each adhesive. The highest shear strength values of both adhesives were obtained in specimens constructed of beech, while the lowest shear strength values were obtained in fir and poplar specimens. Average shear strength of the PUR adhesive was 16.5% higher than that of the PVAc adhesive. Specimens constructed of fir, poplar and sycamore were characterised by the highest percentages of wood failure, whereas the lowest average percentages of wood failure were obtained in beech and oak specimens. With the exception of oak specimens, there was no statistically significant difference between percentage of wood failure among the PUR and PVAc adhesives. Generally, the PUR adhesive showed an acceptable adhesion performance on wood materials used in our study.

The main goal of this study was to determine the effect of wood species and loose tenon length on the withdrawal force capacity of mortise and loose tenon (M&LT) T-type furniture joints. The specimens were manufactured from oak (Quercus alba), beech (Fagus orientalis L.), poplar (Populus deltoides), sycamore (Platanus orientalis), fir (Abies alba), and white walnut (Juglans cinerea), and the tenon species selected was oriental beech (Fagus orientalis L.). The length of the tenon was determined on the basis of the length glued into the horizontal member of the joint. The lengths in the present study were 10, 20, and 30 mm. It was found that joints manufactured from beech had the highest withdrawal force capacity; this trait was lowest in joints made from the light wood of poplar and fir. The glued-in length of the tenon exerted a significant influence on the withdrawal force capacity of the joints. The greatest withdrawal force capacity increment of M&LT T-type joints was obtained when the tenon length changed from 10 to 20 mm.

The goal of this study was to introduce a method for estimating stress analysis as an efficient procedure for evaluating the strength of mitered corner joints in furniture structures. Tests were carried out to determine the effects of panel type, distance between the centers of dovetail holes and the edges of joints (10, 20, and 30 mm), and type of dovetail key on the load-carrying capacity of mitered corner joints under a diagonal tension load. Specimens were constructed of overlaid medium-density fiberboard (LamMDF) and particleboard (LamPb) and connected with butterfly and H-shaped dovetail keys. Polyvinyl acetate adhesive was used to assemble the joints. Specimens were tested under diagonal tension loads and the corresponding combined stress analysis was conducted using the following formulas: Total stress at the outer edge, Total stress at the inner edge, where sb is bending stress, sa is axial stress, P is axial failure load, L is half of the span length, and t and b are the thickness and width of the joint members. Test results showed that corner joints constructed of LamMDF were 13% stronger than joints constructed of LamPb. For the specimens constructed of both panel types, a 10-mm distance between the dovetail holes and the edges of joints gave better results than distances of 20 and 30 mm. No significant differences were observed between the 2 types of dovetail keys. Total compression stresses at the outer edge were 2 times greater than the total tension stresses at the inner edge of the joints.