Analysis of extension–twist coupling of thick-walled composite circular tubes

Abstract

Existing extension–twist coupling in composite tubes can result in undesirable deformations, which may in turn interfere with their normal performance. In this work, a quantitative factor was developed to examine the existence of such coupling in circular composite tubes using the non-classical composite beam theory. The theoretical formulation considered transverse shear and three-dimensional (3D) elastic effects in laminated walls. Therefore, the coupling factor can be used in both thin-walled and thick-walled composite tubes. The numerical values for the coupling factor calculated using the present approach were compared to those obtained from a 3D validated finite element model on 10 composite tubes with different stacking sequences. The findings suggested that the coupling factor could accurately detect existing coupling between extension and twist in composite tubes regardless of their stacking sequence. The paper also proposed a number of design guidelines that could be used in order to eliminate the extension–twist coupling in composite tubes.

Analytical Analysis to Predict the Generated Stresses and Strains of Laminated Composite Tube due to Internal Pressure

“…It can be concluded from Figs. (8)(9)(10) that the radial displacement is compressive and it increases linearly with the thickness. The inner surface has the greatest value of the hoop strain and the outer surface possesses the lowest value of the hoop strain.…”

“…A good match was found between the two analyses. Saeid et al [9] have shown the effect of the extension-coupling effect of composite laminated tubes. The analytical work was performed using the non-classical composite beam theory.…”

“…Figures bellow show the radial displacement and radial, hoop, and shear strains for laminate orientations [90 90 90 90].It can be concluded from Figs (8)(9)(10). that the radial displacement is compressive and it increases linearly with the thickness.…”