Torsional failure analysis of steel strip reinforced flexible pipes connected with end fittings

Flexible pipes function effectively in practical applications only when they are securely connected to specific components using specially designed end fittings. These end fittings must be precisely manufactured to ensure a tight connection, preventing any potential leakage. Otherwise, even perfectly manufactured flexible pipes will fail to perform their intended function. Although extensive research exists on the mechanical analysis of flexible pipes, studies on pipes connected to end fittings are scarce. The primary challenge in investigating this combined structure lies in the complex interaction between flexible pipes and end fittings after assembly, in addition to the already intricate structural behavior of flexible pipes. This paper presents both experimental and numerical analyses. Experimentally, we conducted comprehensive torsion tests on steel strip reinforced flexible pipes connected to commonly used end fittings, observing various torsional failure modes. On the numerical side, we developed a method to model the interaction between flexible pipes and end fittings. The proposed approach enables the prediction of torsional failure modes in practical applications and lays the groundwork for further failure analysis under different loading conditions and for various end fitting designs. • Torsion tests of steel strip reinforced flexible pipes (SSRFPs) connected with end fittings under clockwise torsion and anticlockwise torsion are designed to obtain the torsion behaviors and the corresponding failure modes. • An approach is proposed to address the interaction between pipes and end fittings. • A model is proposed for the analysis of pipes connected with end fittings. • Sensitivity studies provide deeper insights and contribute to the enhanced design of SSRFPs connected with end fittings.