Properties Of Spruce Research Articles

The Influence of Alternating Lower and Higher Temperatures on the Bending Characteristics of Glued Norway Spruce (Picea abies (L.) H. Karst.) and European Larch (Larix decidua Mill.) Wood

This article deals with the effect of alternating lower (freezing) and higher (heating) temperatures on the static bending characteristics of glued Norway spruce (Picea abies (L.) H. Karst.) and European larch (Larix decidua Mill.) wood. Two types of wood, PUR (polyurethane), and EPI (emulsion polymer isocyanate), were used for the experiment. The thermal loading of glued wood was carried out at temperatures −15 °C/70 °C and −25 °C/70 °C. Static bending characteristics were determined on glued wood samples and compared with the reference samples. Freezing causes an increase in the bending properties of both glued spruce and larch wood. The highest in bending strength was obtained for EPI-glued larch wood subjected to −25 °C/70 °C loading temperature, which is by as much as 20% increase from the reference value. The maximum improvement in the modulus of elasticity was achieved for EPI-glued larch with around 11% increase, although the increased values of bending strength and modulus of elasticity were not significant. The different densities, anatomical structures, and properties of spruce and larch wood can induce varying results between the two wood species.

Установление целевых свойств и характеристик еловых лесов, обеспечивающих повышение их устойчивости

Presented in the work decision is also based on the use of silvicultural method of priority-target systematization of natural and anthropogenic factors of influence on forests certain rock formations,established in accordance with natural conditions and bio-ecological properties of spruce forest species science-based target characteristics as the individual plantings,and their ag-gregates (forest fund), for which is developed and applied appropriate systems silvicultural oper-ations ensuring achievement of the established parameters.

Effects of Industrial Heat Treatment on the Properties of Spruce and Pine Woods

The purpose of this study was to evaluate the effects of an industrial heat treatment (ThermoWood) based on changes in the strength properties, density, and color of spruce (Picea abies) and pine (Pinus sylvestris) woods. Samples were subjected to heat treatment processes at 212 °C for a duration of 120 min. The results showed that the applied process caused a 2.56 to 6.12% decrease in density. Dimensional stability was considerably improved, with ASE values of 58% and 52% for spruce and pine, respectively. The color became darker after treatment. The process caused a significant (p<0.05) reduction (8 to 42%) for all investigated mechanical properties at a specific moisture level (12%). However, the mechanical properties of wood are closely related to its moisture content, and heat-treated wood is less hygroscopic than untreated wood. It was found that, after long-term acclimatization, heat-treated samples had almost half the equilibrium moisture content of control samples. Because the changes that occurred after this heat treatment are irreversible, it is possible that ThermoWood has lower equilibrium moisture content than untreated wood. Therefore, this should be taken into account when investigating the mechanical design values of heat-treated wood.

Investigation on Failure Mode of Spruce under Different Loading Conditions

Compression experiments of spruce along axial, radial and tangential loading directions are implemented by INSTRON equipment. Mechanical properties of spruce along three directions are gained. Spruce microscopic cell failure modes under axial, radial and tangential compression condition are observed by scan electron microscope. Results show that failure modes of spruce are fiber buckling and wrinkle when loading direction is along the grain. When loading direction is along radial or tangential across to the grain, failure modes are wood fiber slippage and delamination. Theory analytic solution to single wood cell failure under different direction compression is done. The obtained expression shows that mean limit loading is relative to yield stress, cell structure dimension and wrinkle length for complete wrinkle cases.

Root hydraulic properties of spruce measured with the pressure probe

The root pressure probe was used for the first time to measure the hydraulic properties of entire root systems of youngPicea abies. Hydraulic conductance was measured by osmotic and hydrostatic pressure relaxation techniques. Osmotic experiments were conducted by changing the nutrient solution and hydrostatic experiments by causing flow across the root with the pressure probe and with external pressure applied to the root system or to the cut stem of the excised root system. Usually,Picea abies root systems did not develop appreciable root pressure (< 0.02 MPA) and could be induced to reach a root pressure of 0.07 MPa by treating with KNO3. In general, hydraulic conductance of the root system was large, but it was much smaller in the osmotic than in the hydrostatic experiments. Both hydrostatic techniques gave similar results. The results were explainable by a composite transport model of the root.

Drying of Porous Materials in a Medium With Variable Potentials

This paper presents an application of the Luikov system of heat and mass transfer equations in dimensionless form to predict the temperature and moisture distributions in a slab of capillary-porous material during drying. The heat and mass potentials of the external medium in the boundary conditions are assumed to vary linearly with time. The method of solution is illustrated by considering the drying of a slab of lumber. Numerical results based on the estimated thermophysical properties of spruce are presented.

Impact of water storage on mechanical properties of spruce as detected by ultrasonics

The impact of a five months water storage together with a bacterial treatment, on the mechanical properties of spruce is analysed by ultrasonic waves. The Bacillus subtilis is used to improve the permeability of spruce sapwood. The attack of bacteria on the torus of aspirated pits is expected to lead to a better transport of preservative liquids. The elastic constants were calculated through ultrasonic velocities which were measured at different types of specimens. The results were compared with the constant EL as determined by a static bending test. The calculated loss of strength seems to be negligible but variations in the elastic properties of anatomical plaines consisting radial axes, can be well predicted.