Research on Fatigue Parameter Detection of Free Spanning Based on Multi-Measure Fusion

Submarine pipeline is the lifeline of offshore oil transportation. Affected by seabed earthquake, seabed depression, obstacle and other factors, submarine pipeline is easy to produce free spanning. Under the action of complex environmental load, the free spanning is prone to produce vortex induced vibration (VIV) characterized by fluid structure coupling. The alternating stress produced by vortex induced vibration, as a low cycle fatigue load, leads to pipeline fatigue, failure and even fracture. Fatigue parameter is an important index to judge whether the free spanning is threatened, and it is the data support of pipeline safety assessment. Frequency and displacement are the most important parameters to reveal the state of the pipeline, which it is very difficult to detect the fatigue parameters under the strong ocean background noise. Based on the study of the dynamic response characteristics and stochastic resonance (SR), this paper proposes a multi-measure fusion method for the detection of the free spanning fatigue parameters. To verify the effectiveness of the above methods, computer simulation experiment is carried out. The test results have verified the effectiveness of the proposed approach, especially in the region of low SNR circumstance.