Fatigue Analysis of a Flexible Riser at Different Loads

The detailed finite element model of a ten-layer flexible riser 2-m long and 218.4-mm outer diameter was constructed in view of the boundary conditions and interlayer contacts at different loads (including tensile force, internal and external pressures). The analysis of the whole pipe was conducted to determine its main bearing layers. Those layers were extracted for local analysis to calculate the fatigue life. The internal and external armors were the main bearing layers in tension. The preparatory and interlocking pressure protection armors were the main bearing layers under external or internal pressures. The fatigue lives were 7.605 center dot 10(5) , 1.905 center dot 10(5), and 3.723 center dot 10(5) cycles, respectively, at cyclic loads. The main bearing layers can endure higher tensile force, external and internal pressures, which indicates that the ten-layer flexible riser can be used for engineering operations in aquatic environments.