A finite element method assessment of a Steel Tube Umbilical (STU) cable subjected to crushing load: Comparison between two and three-dimensional approaches

Abstract

Umbilical cables are fundamental equipment used in deep and ultra-deep water oil and gas production systems. The complexity of such structures usually enforces the use of numerical tools. This paper presents and compares two different numerical approaches for prediction of stress and strain fields in the umbilical cable components under crushing loads, which are imposed to the umbilical during laying operation. The first approach, presented in a previous work [1], is based on a joint analysis using a two-dimensional finite element model fed by analytical models, which represent three-dimensional effects. The second approach, used here as a paradigm, is based on a full three-dimensional finite element model, in which the three-dimensional effects are intrinsically considered. An armoured Steel Tube Umbilical Cable is used as a case study in order to compare both methodologies. It is shown that, while being much faster, the two-dimensional approach yields consistent results when focus is directed onto the components of the central core, as steel tubes. Elastic-plastic behavior is adopted for the steel tubes in both models.