Timber mechanical properties assessment relies on grading methods that use non-destructive measurements in input, among which fibre orientation gives satisfactory outcomes. Several models exist in the literature to use fibre orientation data, based on either classical beam theory or finite element modelling. The present paper proposes to compare them for axial and bending loadings. To this end, the main approach was to use several artificial beams, for which fibre orientation was modelled around various knot positions in the tangential plane of wood. It is shown that beam theory modelling, despite considering the heterogeneity of moduli of elasticity in beam longitudinal direction, does not truly represent the actual deformations that can be depicted with finite element modelling. It results in significant differences in the accuracy of the assessment of the local modulus of elasticity, the finite element modelling being better. This finding was supported by experimental results obtained on laminated veneer lumber beams with a high knottiness. Additionally, this paper provides a comparison of different methods to compute localized moduli of elasticity that are typically used as strength predictors. The outcomes indicate that their behaviour depends on the loading type (axial or bending), the knot position in the beam, and the length of the sliding window across which they were computed. A localized bending modulus of elasticity (MoE) computed from the displacements, referred to as the 'apparent MoE', was defined in the objective to improve the accuracy of strength predictions.

木材机械性能评估依赖于在输入中使用无损测量的分级方法，其中纤维取向给出了令人满意的结果。文献中存在几种使用纤维取向数据的模型，它们基于经典梁理论或有限元建模。本文建议对它们的轴向载荷和弯曲载荷进行比较。为此，主要方法是使用几根人造梁，围绕木材切面的各个结位置对纤维取向进行建模。结果表明，梁理论建模尽管考虑了梁纵向弹性模量的异质性，但并不能真正代表有限元建模可以描述的实际变形。这导致局部弹性模量评估的准确性存在显着差异，有限元建模效果更好。这一发现得到了在具有高节数的层压单板木梁上获得的实验结果的支持。此外，本文还对计算通常用作强度预测因子的局部弹性模量的不同方法进行了比较。结果表明，它们的行为取决于载荷类型（轴向或弯曲）、梁中的结位置以及计算它们的滑动窗口的长度。目标中定义了根据位移计算的局部弯曲弹性模量 (MoE)，称为“表观 MoE”，以提高强度预测的准确性。