| The use of flexible composite pipe for the high pressure applications in the oil and gas industry provides the opportunity to overcome many of the problems associated with traditional steel or rigid fibreglass pipelines. The plastic and fibre-reinforced materials employed provide superior chemical resistance to that of steel structures, while and independent, multilayered construction allows structural flexibility. However, design and analysis of such a system is considerably more complex than that of any mono-material construction. Several different models have been developed to deal with the interaction between the individual components.;Global models utilize equations of compatibility, equilibrium and constitutive relations for the composite material to determine growth and rotation (or axial force and torque) developed through internal pressure. A number of simplifying assumptions necessary for these models allow consideration of unidirectional fibre tension only and preclude the modelling of individual components with respect to secondary stresses. These additional stresses are caused by localized bending and have, through experimentation, been shown to cause premature failure of the pipe under internal pressure.;In this thesis, secondary stresses have been studied in detail using finite element analysis. A greater understanding of the factors causing secondary stresses has been achieved and methods of reducing the stress levels have been developed. |
