Abstract
Oil and gas exploration and exploitation in deep and ultra-deep waters challenges classical riser technology and configuration. New technologies, including carbon fiber as composite armors, influence weight and strength of the riser. This can allow for more simple configurations compared with conventional ones, simplifies installation procedures and eventually lead to reduced costs. The new fiber reinforced cross section sheaths requires new analytical models in the local stress analysis tools. The current paper explores efficient and accurate implementations of orthotropic laminate sheaths into classical cross section simulation tools. The model is based on a classic partition of the analysis scheme into a combined load and response model consisting of an axisymmetric and pure bending part. The suggested model is based on full 3D elasticity solution that allows for thick cylindrical laminates taking into account all stress and strain components. The model is compared with 3D Abaqus results for a number of different lay-ups and the results show excellent agreement with the more advanced 3D simulations in both axisymmetric and bending response modes. The laminate, a thermoplastic composite layer with carbon fibers, is used as a component in an unbonded flexible pipe. The cross-sectional analysis is thus performed in the classical way.
