Stress Wave Propagation in Larch Plantation Trees-Numerical Simulation

Abstract

In this paper, we attempted to simulate stress wave propagation in virtual tree trunks and construct two dimensional (2D) wave-front maps in the longitudinal-radial section of the trunk. A tree trunk was modeled as an orthotropic cylinder in which wood properties along the fiber and in each of the two perpendicular directions were different. We used the COMSOL Multiphysics® software to conduct numerical simulations. Field stress wave timing measurements were then conducted on three freshly cut larch (Larix principis-rupprechtii Mayr) logs to validate the simulation results. The 2D wave fronts observed through numerical simulations were in good agreement with those obtained through stress wave timing measurements. When a stress wave was introduced into the tree trunk through a point impact, it initially propagated in the impact direction with a spherical wave front; then the flow of stress wave energy gradually changed toward the longitudinal direction and its wave front became flattened perpendicular to the longitudinal axis. Our preliminary results indicate that the Structural Mechanics module of the COMSOL Multiphysics® software is capable of simulating the longitudinal wave propagation in standing trees.

Citation

Liu, Fenglu; Jiang, Fang; Wang, Xiping; Zhang, Houjiang; Yu, Wenhua. 2015. Stress Wave Propagation in Larch Plantation Trees-Numerical Simulation. USDA Forest Service, Forest Products Laboratory, General Technical Report, FPL-GTR-239, 2015; pp. 418-427.