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- Assessing wood quality by spatial variability of transverse elastic properties within the stem: Case study on P. pinaster at the meso scalePublication . Pereira, João Luís Esteves; Xavier, José Manuel Cardoso; Lousada, José Luís Penetra Cerveira; Silva, Abílio Manuel Pereira daIn this work the radial and longitudinal variations of maritime pine (Pinus pinaster Ait.) transverse elastic properties, within the stem, were investigated. Ring-oriented tensile tests through five radial positions and three height levels were carried out in 750 radial-tangential specimens, at the growth ring scale (meso scale). The strain fields over the gauge section were measured by digital image correlation. A suitable balance between accuracy and spatial resolution was achieved in order to reconstruct the gradient strain fields generated by the material heterogeneity at the growth rings level. A segmentation technique based on image processing and analysis was implemented in order to split each annual ring cross the region of interest, into three main tissue layers: resin channels, earlywood (EW) and latewood (LW). Accordingly, transverse elastic moduli of each EW and LW layers were then estimated by two different identification methods: the Anisotropicbased Method (AbM) and the Virtual Fields Method (VFM). The VFM was applied to directly identify in-situ Q11 and Q66 stiffness components associated to EW and LW. The AbM was applied to the global ER and GRT evaluation. These effective elastic properties were then used to infer the local ones as a function of mean density, combining the application of a micromechanical model (mixture law) and a unit cell model. The Q11 and Q66 LW/EW ratios were found in the order of 1.32 and 2.45, respectively. These ratios suggest a linear relationship between elastic properties and density. Furthermore, the spatial variability of the elastic properties was analysed and related to the meso structure heterogeneity, which was given namely by means of density measurements provided by Xray microdensitometry. The results were found in good agreement, presenting significant correlations with density. Specifically, both effective ER and GRT were most often up to approximately 90% determined by mean density.