The problem of azimuthal shear deformation of a transversely isotropic elastic
circular cylindrical tube is considered and studied in the small deformation regime.
The preferred direction of the transverse isotropy is assumed to lie on the plane of
the tube cross-section and is due to the existence of a single family of plane spiral
fibres. Consideration of the manner that either the tube material or the fibres may be
constrained gives rise to four different versions of the problem which are all
susceptible to an exact closed form solution when fibres are perfectly flexible.
Particular attention is paid to the special case of straight fibres aligned along the
radial direction of the tube cross-section, where comparisons are made between the
aforementioned solution obtained when fibres are perfectly flexible and a
corresponding solution obtained when fibres posses bending stiffness. It is found
that the conventional linear elasticity considerations associated with the
perfectly flexible fibre assumption cannot adequately account for the effects of
material anisotropy. In contrast, effects of material anisotropy can be accounted
for when fibres posses bending stiffness, by taking into consideration the
action of couple-stress and therefore asymmetric stress. Moreover, an intrinsic
material length parameter which appears naturally in the associated governing
equations may be chosen as a representative of the fibre thickness in this
case. It is also seen that deformation patterns of fibres possessing bending
stiffness as well as corresponding stress distributions developed within the tube
cross-section fit physical expectation much closer than their perfectly flexible fibre
counterparts.