DIFFUSION RATE FOR STRESS IN ORTHOTROPIC MATERIALS

Axial rates of diffusion of the symmetrical stare of stress caused by equal but opposed normal forces acting on opposite sides of an indefin itely long strip or plate, are examined in the context of orthotropic elastic materials. To obtain the stress components for this boundary v alue problem, the imposed surface tractions are represented by a Fouri er integral. At distances larger than one quarter of the thickness, th e normal stress on the middle surface is closely represented by the st em of eigenfunctions for this problem, up to, and including the first complex eigenfunction as well as its conjugate. Each eigenfunction is a product Of exponentially decreasing and oscillatory terms. The expon ential term is more significant for determining the rate of diffusion of stress in materials with a large ratio of axial to transverse Young 's moduli E(x)/E(y) greater than or equal to 3; this term shows a stro ng dependence on the ratio of transverse Young's modulus to shear modu lus E(y)/G.