A NUMERICAL MODEL FOR ANALYZING CROSS LAMINATED TIMBER UNDER OUT OF PLANE LOADING

This paper targets the validity of a novel numerical model for analyzing CLT under out of plane loading. This numerical model was initially developed for determining the shear lag effect that appears in laminated thin walled composite beams. A parametric study was conducted in order to determine the influence of orientation of layers in CLT panels on bending strength and deflection. For confirming the accuracy of the proposed model, the results from the numerical model are compared with the external results of the computer software Ansys. The differences in bending stress vary from 0.27% to 1.69% depending on the orientation of layers and for deflection the differences are ranged from 2.25% to 7.42%. A numerical study was conducted and obtained data corresponds to results obtained from experimental study. It was concluded that the proposed numerical method can enough precisely predict the behavior of CLT under out of plane loading

LIGNOCELLULOSIC LINERS BASED ON WOOD WOOL

Basic physical and mechanical properties of lignocellulosic liners up to 1.5 mm thick with a compact and non-crumbling surface based on wood wool and thermoplastic water based glues were determined. PVAc and starch glue with a high proportion of water content were used. The dry mat was pressed gradually under high pressure up to 28 MPa and a temperature of around 190°C with the release of steam. Tests according to the CEPI (Confederation of European Paper Industries) standards were adopted. Procedures for tensile strength according to ISO 1924-2 (2008), Burst strength according to ISO 2758 (2014), puncture according to ASTM D781-68 (1973), water absorption according to ISO 5637 (1989) and porosity according to TAPPI Test method T460 were applied

CHANGE IN SOME ACOUSTIC PROPERTIES OF WOODS USED IN MUSICAL INSTRUMENTS AFTER CHEMICAL MODIFICATION WITH PROPIONIC ANHYDRIDE

The spruce (Picea orientalis), maple (Acer pseudoplatanus), sapele (Entandrophragma cylindricum), cypress (Cupressus sempervirens) and mulberry (Morus alba) woods, which are among the wood types commonly used in making musical instruments, were subjected to chemical modification by propionic anhydride for 1 h, 3 h and 6 h reaction times. The changes in dimensional stability, sound velocities, modal frequencies and dynamic elasticity modulus values of wood samples after modification were investigated. According to the results obtained, as the weight gain values occurring depending on the reaction time increased, the dimensional stability increased in all wood types. When the acoustic properties were examined, it was determined that individual changes occurred at different values depending on the wood type and chemical modification times

LIQUID PERMEABILITY OF EUCALYPTUS UROPHYLLA WOOD TREATED WITH DIFFERENT DRYING METHODS

In this study, the influence of three different drying methods on the liquid permeability of sapwood and heartwood of Eucalyptus urophylla was investigated. The liquid permeability of the dried wood was assessed by measuring the maximum amount of dyeing solution uptake using the capillary rise method. Subsequently, the microscopic structure of the dried wood was examined by scanning electron microscopy (SEM). The results indicated that the liquid permeability of sapwood dried by microwave vacuum drying (MVD) and conventional kiln drying (KD) was significantly more effective than that of air drying (AD) treated wood. However, there is no significant difference in the effect of MVD and KD on the liquid permeability of sapwood. The liquid permeability of heartwood treated with MVD is significantly better than that treated with KD and AD, and the effect in the effects of AD and KD on the heartwood is not significant. The increased permeability of Eucalyptus urophylla wood can be attributed to the occurrence of macro-cracking or micro-structural damage in the test specimens, resulting from the dislodgement of perforated plates within the wood cells, the rupture of the intercellular layer between vessel and axial parenchyma cells, as well as the rupture of the pit membrane in cross-field pits due to microwave vacuum drying and conventional kiln drying

EVALUATION OF WOOD QUALITY OF PINUS MONTEZUMAE LAMB. IN A DISTURBED FOREST USING NON-DESTRUCTIVE ACOUSTIC METHODS

The objective of this study was to evaluate the modulus of elasticity and wood quality for structural use in standing trees of Pinus montezumae Lamb. in a natural forest. An acoustic method was used, measuring the ultrasonic flight time for one cross-sectional and two longitudinal sections in 70 trees. Significant differences were found between the two longitudinal moduli of elasticity, and the P. montezumae trees in the study area show potential for structural use according to the modulus of elasticity. It is concluded that for sustainable management, wood of medium quality would be obtained in the same proportion for the first two sections of the tree stems, while high-quality logs would be obtained in the second longitudinal section (2–4 m)

EVALUATION OF WOOD DAMAGE AND FRACTURE BEHAVIOR BASED ON ENERGY ENTROPY OF ACOUSTIC EMISSION SIGNALS

In order to assess the damage and fracture behavior of wood under continuous loading, an energy entropy and b-value associated with the acoustic emission (AE) signal were defined to quantitatively describe the release of strain energy during loading. Firstly, the acoustic emission signals of the wood in the three-point bending test were collected. This paper presents the concept of energy entropy according to the definition of information entropy. In order to further evaluate the strain energy intensity released by the damage behavior of the wood specimen, the acoustic emission b-value was defined. Finally, by jointly analysing the dynamics of these two parameters, the test process can be divided into three phases. The results show that even in the elastic phase, micro-destructive behavior occur inside the wood specimen; in the plastic phase, the wood specimen is not only subjected to macroscopic damage, but also often accompanied by fine cracks inside

EFFECTS OF CHEMICAL AND PHYSICAL TREATMENTS ON BAMBOO CELL WALL STRUCTURE FROM ENGINEERING PERSPECTIVES

This study focuses on the effects of chemical treatment using polyethylene glycol (PEG) and physical treatment via steam explosion and microwave, with a comprehensive analysis using ATR-FTIR, X-ray diffraction, Keyence VR 6000 optical profilometer, and SEM. The aim is to elucidate alterations in bamboo cell walls following these treatments compared to untreated bamboo. The results reveal significant modifications in the chemical composition and crystalline structure of bamboo cell walls post-treatment. ATR-FTIR analysis indicates changes in functional groups, suggesting chemical interactions and modifications in the molecular arrangement of cell wall components. XRD analysis further corroborates these findings by revealing shifts in crystallinity and peak intensities, signifying structural rearrangements, as evidenced by optical images and SEM micrographs

THE RELATIONS BETWEEN NON-STRUCTURAL SUBSTANCES, ANNUAL RINGS WIDTH AND LATEWOOD SHARE IN PINUS SYLVESTRIS L. STEM

Extractives and ash contents, share of latewood and annual rings width were analyzed in wood at different heights and different zones of the Pinus sylvestris L. stem cross-section. Additionally, the high performance liquid chromatography (HPLC) with a conductometric detector was applied to determine the sulphate (SO42-) and hydrogen phosphate (HPO42-) anions concentrations in wood and bark of Pinus sylvestris L. stem. In this paper, based on the results it was observed, that generally extractives content increased in the direction from sapwood perimeter to middle heartwood and pith adjacent heartwood zone. Moreover, the results showed that the greater share of latewood in annual rings the lower ash and extractives contents in the wood, but the higher sulphate (SO42-) and hydrogen phosphate (HPO42-) anions concentration. The sulphate (SO42-) and hydrogen phosphate (HPO42-) anions concentrations in the bark of the Pinus sylvestris L. stem were higher at the top than at the butt-end part

WOOD ANATOMY INDICES AND REVEGETATION POTENTIALS OF THREE TAXA OF THE EUPHORBIACEAE

The suitability of three plant taxa namely: Bridelia ferruginea, Hura crepitans and Ricinodendron heudelotii as potential revegetation plants in desertified areas were assessed using Calquist’s wood anatomy indices (vulnerability and mesomorphy) using an ecological survey design. Temporal and permanent slides of transverse sections were prepared and vessel length and diameter (µm) measured using a Motic B3 Compound Microscope and vessel density determined for each of the plant taxa. The observed high vulnerability and high mesomorphy index values in Hura crepitans and Ricinodendron heudelotii indicates that they did not fall within the required ranges of 0 – 2.5 and 0 – 99 for the two indices respectively and cannot adapt well in xeric areas. However, Bridelia ferruginea fell within the range. In conclusion, Hura crepitans and Ricinodendron heudelotii are mesophytes while Bridelia ferruginea was xerophytic and can flourish in xeric areas, therefore, it possesses a great revegetation potential

ECOLOGICAL AND FUNCTIONAL COMPARISON OF WOOD ANATOMY ON SOME TREE GENERA IN THE SOUTHERN NIGERIA

This work aimed at utilizing wood anatomical traits to assess the compatibility or suitability of 9 species in the families where they belong since the earlier classification depended only on morphological characters and also to possibly deduce the permeability of their vessel lumen during wood treatment with preservatives of equal or different viscosity. Comparative stem anatomy of tree taxa Antiaris toxicaria Lesch. (Moraceae), Ficus exasperate Vahl. (Moraceae), Milicia excelsa Welw. (Moraceae), Dacryodes klaineana Lam. (Burseraceae) Canarium schweinfurthii Engl. (Burseraceae), Dacryodes edulis Lam. (Burseraceae), Erythrophleum suaveolens Taub. (Fabaceae), Pelthophorum pterocarpum De Cand. (Fabaceae), Pterocarpus soyauxii Taub. (Fabaceae) was studied. Observations on the transverse, radial-longitudinal and tangential-longitudinal sections showed that there were vast variations and few similarities in the vessel, axial parenchyma, ray cell and storied fibre distributions within and across families. Variations across the three ecological zones were found. The highest vessel diameter occurred in C. schwenfortii with 222.84µm (Burseraceae) followed by F. Exasperate with 196.42 µm (Moraceae) and P. pterocarpum with 187.23 µm (Fabaceae) across the three ecological zones. Vessel diameters were in direct proportion with the amount of rainfall while vessel frequencies were in negative proportion with the amount of rainfall across the ecological zones. Qualitative properties were not significantly affected by either temperature or rainfall

PRELIMINARY STUDY OF DEPENDENCE OF SMOKE AND CARBON MONOXIDE EMISSION ON HEAT RELEASE RATE FROM FAST-GROWING WOOD SPECIES

The aim of this paper is to create the model for prediction of carbon monoxide release rate (CORR) and smoke production rate (SPR) from heat release rate (HRR) of fast-growing wood species. The model is independent on wood species, thus is suitable for all fast-growing wood species. Three wood species hybrid poplar J-105 (Populus nigra × P. maximowiczii A. Henry), white willow (Salix alba L.) and black locust (Robinia pseudoacacia L.) were used for universal model creation. The heat release rate, smoke production rate and carbon monoxide release rate have been measured at three heat fluxes (25, 35 and 50 kW.m-2) by the cone calorimeter. The average values of CORR and SPR for all investigated wood species were 0.051 g.m-2.s-1 and 0.086 m2.m-2.s-1, respectively. Both dependencies of SPR and CORR on HRR have shown similar trends during the ignition phase (unstable trend) and during the intense burning phase (roughly linear increasing with HRR). The main difference was shown during the steady state phase (dependency of SPR on HRR is stable while dependency of CO on HRR is highly unstable). The results also proved a significant impact of wood density on these dependencies, thus, the neural network for prediction of SPR, CORR from HRR was applied. The coefficients of determination R2 for trained neural networks, for both SPR and CORR, were achieved in the range from 0.96 to 0.97

THE USE OF BORIC ACID AND ANTIMONY OXIDE AS AUXILIARY MINERALS WITH HUNTITE HYDROMAGNESITE TO IMPROVE FLAME RETARDANT PROPERTIES OF WOODDUST COMPOSITES

Boric acid, antimony oxide minerals and huntite hydromagnesite minerals were used as auxiliary minerals in wood composites to change their flammability features. Composite samples were prepared by using different ratios of sawdust, huntite, hydromagnesite, antimony and boric acid combinations. The obtained samples were characterized by scanning electron microscopy (SEM) analysis to determine the structural and morphological properties of the composites. Thermal behavior of the composites was determined by differential thermal analysis-thermogravimetry (DTA-TG). Tensile and three-point bending tests were performed to understand the mechanical properties. Finally, the flame retardant performance of the samples was observed according to UL94 vertical flammability tests. It was concluded that wood composites containing inorganic minerals gained resistance against fire, a good synergistic effect was obtained in different additive types

ANNUAL GROWTH RING CHARACTERISTICS OF QUERCUS CERRIS (L.) TREES GROWN UNDER DIFFERENT CONDITIONS

The study examined the effect of stand composition and soil quality on radial growth of Quercus cerris (L.) grown in Vas County in Hungary. Twelve trees were randomly harvested, and the sampled wood pieces were extracted from the breast-height portion. Wood strips were machine-sanded, scanned for analysis in ImageJ. Climate data were obtained from a database of the Hungarian National Metrological Service. Mean annual-ring width was larger for trees harvested from mixed species planting site. Overall, annual-ring sizes for trees harvested from pure species stand that thrive on poor soils exhibited wider variation (62%). The same plot of trees had a latewood width variation of 82%. Precipitation correlated positively with annual-ring size with weak to moderate coefficient (0.13 – 0.32), whereas maximum temperature negatively correlated with annual-ring size on moderate coefficient (-0.42)

INCREASING THE EFFICIENCY OF ENZYMATIC HYDROLYSIS OF LIGNOCELLULOSIC MATERIALS BY FREEZING PRETREATMENT

This paper describes the differences between the efficiency of enzymatic hydrolysis of selected lignocellulosic materials after pretreatment by cyclic freezing and thawing. It also discusses the analysis of the positive effect of alkaline conditions on pretreatment. The selected materials were Populus alba L., wheat straw from Triticum aestivum L. and Cannabis sativa. Three pretreatment methods were used to compare the efficiency of enzymatic decomposition of cellulose and cellulose accessibility. The best results show the wheat straw pre-treated at -20°C in the freezer with NaOH addition with a concentration of monosaccharides of 56.6 g.l-1 compared to initial hydrolysed material with a concentration of monosaccharides of 24.4 g.l-1. The results show better digestibility of grass compared to wood dendromass