Constructing Virtual Representations of Laminated Timber Products

Abstract

The complex structure of timber has traditionally been difficult to model as it is a highly heterogeneous material. The density (and hence material properties) for structural species such as Pinus radiata (radiata pine) can vary greatly across the growth rings. Numerical simulation methods are becoming more prevalent as a method of predicting moisture migration, stress and strain distributions, and fungal/rot intrusion in timber. These methods require a virtual description of an individual board that captures the growth ring structure present in these timbers. In this work, a low-cost algorithm based on image analysis techniques and spectral segmentation is developed for generating a virtual representation of a cross laminated timber panel. The virtual model is generated as a triangular prismatic mesh where the nodes are aligned on the growth rings, with specific wood material properties allocated to each mesh element The initial step involves identifying the growth ring structure of a single board by analyzing an image of the end grain. The growth rings are then identified using a spectral clustering algorithm. Next, the centre of the tree (pith) is located by using an iterative constrained least-squares algorithm. The density is computed as a proportional length through the growth ring, when provided with an anatomical image of the cellular structure. This density estimate is then assigned to each mesh element resulting in the virtual reconstruction of a singular board. Meshes of multiple timber boards are then combined to produce the final mesh of a laminated timber product.