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The strength properties of Swedish oak and beech

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Because of their economic impact most research on wood in Sweden is aimed at our needle-leaved species, i.e. pine and spruce. Sawmills and other industrial enterprises using these conifers are also in vast majority, both in number of employees and number of companies. However, there is a viable industrial branch in Sweden, i.e. furniture companies, dealing with broad-leaved species such as oak, birch, and alder. Such industries often import all the wood they use, even if the same type of wood grows in the vicinity. In order to make the Swedish broad-leaved trees more interesting to the wood manufacturing sector, we examined the strength properties of some common Swedish woods, viz. oak and beech. The result shows that our oak specimens had a modulus of elasticity of 12.243 MPa measured by using four-point bending. So-called the Young’s modulus was 11.761 MPa for tension and 15.610 MPa for compression in the fibre direction, i.e. there was a very high difference. The stress just before rupture was measured to 85 MPa for tension and 76 MPa for compression, i.e. there was a surprisingly small difference. For beech, our corresponding values were 13.017 MPa for four-point bending, the Young’s modulus during tension was 13.954 MPa and 130.4 MPa in maximum stress, whilst under compression these values were 13.101 MPa and 84 MPa, respectively.
Young modulus of face layer and core layer in three directions on the example of P2 particleboard. The Young's modulus is main parameter characterizing particleboard material which was tested during the bending test according to EN 310. It also known as flexural modulus or modulus of elasticity. For industrial and comparative usage that bending test is sufficient. However, for the purpose of numerical analysis one material constant is not sufficient to describe the material at an acceptable level. The density is undoubtedly related to the mechanical properties of particleboard. The aim of this research is to determine Young modulus of the core layer and the face of particleboard in three directions on the example of chipboard type P2.
The paper presents the results of studies concerning the Young‘s modulus, critical stress, Poisson‘s ratio and thickness determined for the skin of greenhouse tomato cultivars (Admiro and Encore), and soilgrown varieties (Polset and Surya) comparison. Multivariate analysis of variance and one-dimensional tests [Hinkelmann 2008] were carried out. With the contrasts application the greenhouse varieties were compared with soil-grown ones. The comparison inside both: the greenhouse and soil-grown groups were also conducted. The homogeneity groups containing the average values of defined mechanical parameters of the tomato skin were determined.
Presented work introduces the results of comparative analysis concerning selected mechanical properties of greenhouse Admiro and Encore and soil-grown Surya and Polset tomato’s cultivars skin, stored at 13°C. A statistically significant effect of both: variety and storage time on the Young’s modulus, critical stress and Poisson’s ratio values was observed. The Young’s modulus determined for greenhouse fruit’s skin demonstrated considerably higher values than observed for the soil-grown varieties, in addition the highest values were set for an Encore while the lowest one for a Polset variety. The values of Young’s modulus and critical stress decreased with the storage time growth while the Poisson’s ratio remained in the range from 0.4 to 0.49. Poisson’s ratio, established for greenhouse tomato’s peel, took higher values than in the Encore variety case.
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