Experimental and numerical investigation of effects of fiber orientation of wood stiffness

Abstract

Wood is one of the most useful and important natural materials with diverse applications in civil, architectural and constructional engineering. The stiffness of the wood depends on the fiber orientation, distribution of knot and percentage of latewood, etc. Japanese cedar (Cryptomeria japonica) was used to prepare the tensile test specimen in this paper to investigate the effects of fiber orientation on wood stiffness. Before performing the tensile test, surface image of the test specimen was captured and the image was analyzed by least squares method and digital image processing software of MATLAB to obtain the fiber orientation. Based on the obtained fiber orientation, finite element method (FEM) software package ANSYS was employed to calculate the strain distribution of the test specimen. Three-dimensional digital image correlation (3D-DIC) method was also used to verify the FEM results. The DIC software, VIC-3D, was used to analyze the surface deformation of the test specimen under tension. Strain distribution differences between the earlywood and latewood were investigated. With the integration of the digital image analysis technique, FEM and 3D-DIC method, the effective stiffness of the wood can be predicted and the reliability and safety of wood construction can be ensured.