The Elastic Constants for Specimens Possessing Fibre Symmetry

1 The Elastic Constants for Specimens Possessing Fibre Symmetry 

Studies of mechanical anisotropy in polymers have for the most part been restricted to drawn fibres and uniaxially drawn films, both of which show isotropy in a plane perpendicular to the direction of drawing. The number of independent elastic constants is reduced to five [3, p. 138]. Choosing the 3 direction as the axis of symmetry, the compliance matrix sy reduces to 

The relationships of these compliance constants to the better-known Young s moduli and 

Consider application of a stress along the 3 direction, that is along the fibre axis, or the draw direction for the polymer film. Then 633 = 533CT33 and 

Similarly the strain in the plane transverse to the fibre axis for a stress T33 along the fibre axis is given by Cn = C22 = 13 33 and 

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