Simulation of the Mat Formation Process

Abstract

The parameters of the hot-pressing process have a substantial effect on the final mechanical and physical properties of wood-based composites. The number of interacting variables during the consolidation is prohibitively large to assess a wide variety of data by experimental means. A combined stochastic and deterministic model, based on fundamental engineering principles, was developed and validated for establishing the critical relationships between the processing parameters and the physical properties of oriented strandboard (OSB). In the first phase of this research, a Monte-Carlo simulation model was developed for describing the spatial structure of a three-layer OSB. The model was designed to mimic the strand deposition during the mat formation, including the three-dimensional spatial geometry, orientation, and density of the strands. These physical characteristics of the mat formation process were considered as stochastic variables that can be described by well-developed probability distributions. The parameters of these underlying distributions were derived from data collected on industrial strands by using an image analysis technique. The model superimposes a grid on the simulated mat and is capable of computing the number of strands, as well as the thickness and density of the mat, at each grid point. Additionally, it can predict the change in several void volume fractions and strand contact area within the mat during the consolidation. The model has application to wafer, particle, and fiber mats as well. This structural simulation model is the basis of further model development that describes the heat and mass transfer processes, and the viscoelastic nature of the hot-pressing operation during OSB manufacturing.