Vol.:(0123456789) Wood Science and Technology https://doi.org/10.1007/s00226-019-01096-x 1 3 ORIGINAL Determination of elastic properties of latewood and earlywood by digital image analysis technique Tzu‑Yu Kuo 1  · Wei‑Chung Wang 1 Received: 7 November 2018 © Springer-Verlag GmbH Germany, part of Springer Nature 2019 Abstract The proportion of latewood varies from species to species and from site to site. To understand the stifness of wood structures, it is necessary to accurately determine the modulus of elasticity (MOE) of the wood. In this paper, a digital image correla- tion method was used to analyze the surface strain of wood specimens during tensile testing and calculate the Poisson’s ratios of latewood and earlywood. Digital image analysis (DIA) and X-ray densitometry (XrD) techniques were employed to deter- mine the latewood proportion. Good agreement was observed between the DIA and XrD results for the sapwood proportion. Based on the rule of mixtures, the efective MOE was calculated based on the MOEs of earlywood and latewood. Introduction Wood is a composite material found in nature. Because of international advo- cacy for energy efciency and carbon reduction, wood has been widely used in various components of architecture and engineering structures. However, the mechanical properties of wood, for example, the modulus of elasticity (MOE) and maximum tensile strength, are afected by the presence of knots, the late- wood proportion, and the microfbril angle of S2 layers of latewood tracheid (Zhu et al. 2005). The proportion of latewood varies from species to species and Part of this work has been presented at the 2016 World Conference on Timber Engineering (WCTE 2016), Vienna, Austria, August 22–26, 2016, with the title “Tzu-Yu Kuo and Wei-Chung Wang, Determination of Efective Modulus of Elasticity of Wood from Proportion of Latewood”. Electronic supplementary material The online version of this article (https://doi.org/10.1007/s0022 6-019-01096-x) contains supplementary material, which is available to authorized users. * Wei-Chung Wang wcwang@pme.nthu.edu.tw Tzu-Yu Kuo asmit.com@msa.hinet.net 1 National Tsing Hua University, Hsinchu, Taiwan, ROC