Simulation and Analysis of Hygroscopic Warping of Sawn Timber by a Finite Element Method

Abstract

Wood warps due to differential shrinkage or swelling when the moisture content (MC) of the wood changes. Anisotropy and non-homogeneity of solid wood are the main causes for this behavior of wood when it experiences variations in MCs. This warping phenomenon causes considerable reductions in product value, frustration for manufacturers, and loss of confidence by consumers. Therefore, the warping of wood is a leading technical problem and deserves further investigation. The objectives of this study were to propose an analytical method and develop a three-dimensional (3D) finite element model (FEM) to examine the warping behavior of solid wood.A 3D FEM was developed to simulate and analyze the hygroscopic warping of sawn timber with the commercial software, ANSYS (vers. 5.3; ANSYS, Canonsburg, PA). Through this potent tool, the FEM and the deformed geometry were graphically demonstrated. This specially developed FEM was applied here to understand warping due to MC gradients in solid wood. Formulation of the governing equations, detailed model development, computer simulation results are presented in the text.It appears that the simulation and analysis were successfully carried out in this study. These results suggest that this FEM adequately reflects hygroscopic deformations of flat-sawn and quarter-sawn plates and can help practitioners understand the complex warping behavior and generate ideas on how to reduce the magnitude of warping.