Analysis of Mechanical Properties of Pipes with Helical Reinforcement under Axial Tension

Abstract

Flexible pipes with helical reinforcement are widely used in the marine engineering and tissue engineering because of their low bending stiffness. Through appropriate design, they could also meet the strength requirement. All studies on this kind of structures regard the pitch angle of helical wires, strips or fibers as a vital parameter influencing the mechanical properties. In this study, we compare the tensile property of pipes with helical reinforcements braided in different initial pitch angles. Contact pressure is taken into consideration and eliminated by using deformation compatibility equation. The pitch angle changes under axial tension which induces the geometric nonlinearity. It is noted that when the pitch angle is larger than a critical value, even if there is no internal or external pressure, helixes will contact with the core under axial tension. But the initial pitch angle can not be too large since the contact pressure will induce partial buckling of the flexible pipe.