Investigations of Flakeboard Mat Consolidation Part II. Modeling Mat Consolidation Using Theories of Cellular Materials
Keywords:Oriented strandboard, cellular materials, modeling, stress-strain behavior
AbstractThis work tested the applicability of theories designed to predict the compressive stress-strain behavior of cellular materials for modeling the consolidation of a wood flake mat. Model mats designed to simulate narrow sections of randomly aligned and preferentially oriented flake mats were compressed at ambient temperature and moisture conditions in a specially designed apparatus fitted to a servo-hydraulic testing machine. Load and deflection data were collected in real time, and theoretical equations designed to predict the compression of cellular materials were fit to the experimental data. Wood flake mats are cellular-cellular materials, exhibiting two overlapping phases of densification and a highly nonlinear stress-strain response. No differences in the observed stress-strain responses of mats resulted from variations in flake orientation. Theoretical models developed for the stress-strain relationships of cellular foams were fairly effective in predicting the stress-strain relationships of wood flake mats at strains less than 70%. At higher strain levels, the relative density surpassed the initial flake density, causing a violation of model assumptions and forcing the predicted stress levels to increase asymptotically. Combining one cellular material model for the densification of the mat with another for the densification of the wood flakes may be an effective way to model the complex mechanical behavior occurring during consolidation of a wood flake mat.
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