| Umbilical is one of the key equipment in subsea oil and gas development,which is treated as the nerve line of subsea production system.The fatigue design is necessary to make sure safe performance during the serve life.However,the traditional design relies on introducing safety factor without considering uncertain factors,which is necessary for the working condition.Fatigue resistance performance and reliability analysis are introduced in this paper from both the configuration and cross section aspects to advance the traditional umbilical design system.The umbilical global configuration is usually presented as a lazy-wave type under the characteristics of ocean environment.The anti-fatigue configuration design of the umbilical is proposed based on anti-fatigue design criteria.The surrogate function with high-precision and low-calculation mathematical model is established between parameters and the overall line length,fatigue response.The multi-objective optimization design model is constructed by combining surrogate model technology with parameters controlling umbilical global configuration as design variables,and the global configuration length and the combination of equivalent fatigue stress are treated as objectives.Considering the massive calculation problem caused by large number of working conditions in the evaluation of umbilical fatigue life,fatigue condition screening technology is introduced in this paper.Then,the umbilical global configuration with anti-fatigue performance and economic cost is obtained while computational cost can be significantly reduced.The umbilical is a structure with helically wound components,and the cross-section design always determine its function and mechanical performance.Considering the importance of steel tube in umbilical,the fatigue reliability of the top cross-section connecting float is analyzed in this paper by introducing the uncertainties in size,material properties of steel tube and fatigue calculation criteria under specific global configuration design.The sensitivity analysis of reliability on parameters is carried out to evaluate their influence and advance the design with better fatigue reliability.This paper relies on the“863”National High-Tech Research and Development Plan in 12~thh Five Year.Taking the practical umbilical of a certain sea as an example,the anti-fatigue umbilical configuration optimization design and fatigue reliability analysis are applied.Finally,the results compared with traditional original design are presented to verified these methodologies more feasible and effective. |
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