A method to analyze the pure bending of tubes of cylindrically anisotropic layers with arbitrary angles including 0° or 90°

A method is proposed to analyze the pure bending of composite tubes made up of layers of angle 0° or 90° together with other arbitrary angles. It is found that in an earlier approach some of the parameters are singular for a few layer orientations even though the stresses and displacements are nonsingular. These singular terms cannot be simply eliminated as the conventional technique for the singular terms in the stresses in the form of polar coordinates. Otherwise, the continuity conditions at the interface between special and ordinary layers cannot be satisfied. Therefore, the new unified coefficients as well as their nonsingular parameters are introduced and an approach is suggested which is efficient for any case. Several composite tubes are provided to illustrate the proposed method. Besides, the results by NASTRAN are employed for comparison. They are in good agreement to each other.