Validation of Umbilical Fatigue Analysis by Full-Scale Testing

摘要

A highly efficient umbilical analysis scheme for consistent fatigue life calculation of metallic helix elements such as steel tubes, armor wires in umbilicals, and flexible risers is briefly discussed in this paper. This scheme was developed by DNV GL and is used in the commercially available umbilical analysis tool Helica. The calculation efficiency is due to an analytical calculation of helix bending stresses assuming so-called loxodromic helix geometry (i.e., slip is assumed to take place in the axial helix direction only). DNV GL, along with Ultra Deep, launched a joint industry project (JIP) to validate the loxodromic assumption, which is used in local analysis stress calculations of umbilicals and flexible pipes, by comparing calculations with high-quality bending test measurements. Validation against high-tension/low-tension bending tests is considered to cover umbilicals installed at normal to deep water depths. Details of the validation methodology and sample results are presented in this paper.