Fundamental Concepts Concerning the Mechanics of Wood Deformation

Underlying assumptions of classical continuum theory are reviewed in terms of their applicability to predicting the mechanical behavior of wood. Concepts of stress, strain, and the application of the equations of rate of change of momentum (or equilibrium in the limiting case) are discussed from a fundamental point of view. The theoretical idealization of linear elasticity is developed from thermodynamics. Relations of orthotropic elasticity which are generally applicable for wood and plywood are developed from the most general elastic relations employing arguments of elastic symmetry and theomodynamics. Limitations in the interpretation of elastic stress and strain resulting from the inherent nonhomogenity of wood are discussed. The meaning of stress as a statistically averaged quantity in a non-homogeneous medium is discussed. The idealization of linear viscoelasticity is described and noted as an acceptable model for predicting the time dependent behavior of wood at low stress levels. The article is the first of a series of three articles. Subsequent articles are concerned with the strength and plastic behavior of wood and the development of methods for accounting for the essential nonhomogeneity of wood.

You must be logged in to download any documents. Please login (login accounts are free) or learn how to Become a Member