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首页> 外文期刊>Holzforschung >Variation and serial correlation of modulus of elasticity between and within European oak boards (Quercus robur and Q. petraea)
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Variation and serial correlation of modulus of elasticity between and within European oak boards (Quercus robur and Q. petraea)

机译：欧洲橡木板之间和内部的弹性模量（栎栎和栎）的变化和序列相关性

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摘要

This research aimed at describing the tensile modulus of elasticity (MOE), density and knot variability between and within oak (Quercus robur, Q. petraea) boards, which is essential for the stochastic modeling of wooden composites, such as glulam. Longitudinal deformations for 100-mm long cells were measured. The local density variation along boards revealed a very low mean coefficient of variation (COV) of 3%. The global MOE was precisely predicted from local (cell) MOEs, which span from 2.6 to 22 GPa. The mean COV of local MOE along board length was 12%, with extremes of 3% and 28%. The cell-related relationships of MOE with either density or knot area ratio showed low R-values of 0.4 and 0.3, respectively. A multivariate linear regression with both variables increased the MOE prediction to R=0.6, which is below the literature results for beech and spruce wood. A serial correlation analysis of the local MOE was performed for board segments quasi-free of knots and for all cells, investigating different normalization approaches. Applying no MOE normalization delivered too high correlations due to pronounced inter-board MOE variations. A normalization based on an averaged maximum MOE per board delivered reasonable serial correlation results for the first four lags of the MOE knot-free variation (0.61; 0.38; 0.19 and 0.08). Considering also the knot-affected cells reduced the serial correlation roughly by a factor of 2.
机译：这项研究旨在描述橡木（Quercus robur，Q。petraea）木板之间和之内的拉伸弹性模量（MOE），密度和结节变异性，这对于木制复合材料（例如胶合木）的随机建模至关重要。测量了100毫米长电池的纵向变形。沿木板的局部密度变化显示出非常低的平均变异系数（COV）为3％。全局MOE是根据本地（单元）MOE（范围从2.6至22 GPa）精确预测的。沿板长的本地MOE的平均COV为12％，极端值为3％和28％。 MOE与密度或结节面积比的细胞相关关系分别显示出低的R值0.4和0.3。具有两个变量的多元线性回归将MOE预测值提高到R = 0.6，低于山毛榉和云杉木材的文献结果。对准无节的板段和所有单元进行了局部MOE的序列相关分析，研究了不同的归一化方法。由于显着的板间MOE变化，未应用MOE归一化传递的相关性太高。基于每块板平均最大MOE的归一化为MOE无结变化的前四个滞后（0.61、0.38、0.19和0.08）提供了合理的序列相关结果。还应考虑受结影响的细胞将序列相关性大约降低了2倍。

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