Theoretical and numerical models of innovative cross-sections for flexible pipelines in research and design

The thesis is focused on two different issues relative to reinforced flexible pipelines for the unbonded cases: tensile force and external pressure. Mainly, the work is carried out comparing theoretical and numerical models for what concerns reinforced flexible pipes, then the analytical models were used for parametric studies and comparison with composite - based pipelines. For the numerical simulation, the FEM software used was ABAQUS. The elevation point for the tensile load case was involving the pressure armor layer in the design of the cross-section and exploiting the plastic properties of the materials, obtaining a valid estimation for the pipe's tensile strength. While for the hydrostatic load case, the elevation point was to carry out a formulation valid for the minimum requirement for the initial ovality in terms of both radial displacements and collapse pressure.