Drying and Shrinkage

All strength properties of wood vary with the orthotropic axes of the wood the best approximation of the allowable stress is given hy Hankinson s equation as follows  

Notes G is the specific gravity of the oven-dry mass to the volume at given moisture content. 

Young s modulus. The modulus of elasticity is also highly anisotropic. The modulus of elasticity perpendicular to the grain is l/20th of the modulus parallel to the grain. Mechanical properties also depend on imperfections of the wood. Knots in the wood can decrease the 

Fracture toughness. The orthotropic nature of wood also affects its fracture mechanics. Actually, timber fractures along the grains irrespective of the opening force and original notch geometry. 

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Examples for the application of mesh-free methods to the question of structure formation can indeed be found for drying processes. Ito and Yukawa modelled the evolution of cracks within a drying paste by the use of the mesh-free SPH method [6]. Karunasena et al. simulated drying and shrinkage of cells in food stuff with a coupled SPH-DEM approach [7]. These models have been developed parallel and independently to our work and address very different kind of drying mechanisms. StiU, they underline the applicability of a mesh-free approach to modelling morphology evolution. 

TABLE 57 Linear Shrinkage of Clays on Drying and Strength of Dry Clays... 

Del Valle, J.M., Cuadros, T.R.M., and Aguilera, J.M. 1998. Glass transitions and shrinkage during drying and storage of osmosed apple pieces. Food Res. Int. 31, 191-204. 

Table 1.31 Effect of the direct addition of water-reducing admixtures on the drying creep and shrinkage of concrete...

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