INVESTIGATIONS OF FLAKEBOARD MAT CONSOLIDATION .2. MODELING MAT CONSOLIDATION USING THEORIES OF CELLULAR MATERIALS

This 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 simulat e narrow sections of randomly aligned and preferentially oriented flak e mats were compressed at ambient temperature and moisture conditions in a specially designed apparatus fitted to a servohydraulic testing m achine, Load and deflection data were collected in real time, and theo retical equations designed to predict the compression of cellular mate rials 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 f lake orientation. Theoretical models developed for the stress-strain r elationships of cellular foams were fairly effective in predicting the stress-strain relationships of wood flake mats at strains less than 7 0%. At higher strain levels, the relative density surpassed the initia l 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 mo del the complex mechanical behavior occurring during consolidation of a wood flake mat.