Multi-scale analyses of a floating marine hose with hybrid polyaramid/polyamide reinforcement cords

This study reports a multi-scale structural analyses of a mainline floating double carcass marine hose (nominal diameter 508 mm, length 10.7 m, design pressure 2.1 MPa, weight 4100 kg). A material change in the reinforcement cords of the traditional hose is proposed, from polyester and polyamide to hybrid aramid/polyamide cords, allowing an improvement in design, reducing weight and increasing flexibility. Two models have been developed to obtain the hose responses. Firstly, a finite element model of the traditional system was built to perform a macro-scale analysis of global hydrodynamics loads in the hose line using Orcaflex™ software. Then, a non-linear finite element model was developed for meso-scale analysis using Abaqus™ software. Rubber and cords were modeled using hyperelastic models, and axial, bending and torsional stiffnesses were evaluated. Experimental tests were carried out to assess the mechanical response of an actual full-scale hose. The reduced number of layers of the hose using hybrid cords, compared to the traditional one, allowed a reduction in weight of 15%, and brought also a decrease in specific axial, torsional and bending stiffnesses of 43.9%, 52.2% and 21.6%, respectively. The multi-scale analysis predicted well the structural response of the hose line, and the reduced potential failure may increase life-time of the structure.