Zhang, N.; Li, S.; Sun, B.; Huang, C.; Huang, K.; Zeng, Y.; Liu, C. Flexible Riser Tensile Armor Modelling Method and Application to Fatigue Analysis. J. Mar. Sci. Eng.2023, 11, 1500.
Zhang, N.; Li, S.; Sun, B.; Huang, C.; Huang, K.; Zeng, Y.; Liu, C. Flexible Riser Tensile Armor Modelling Method and Application to Fatigue Analysis. J. Mar. Sci. Eng. 2023, 11, 1500.
Zhang, N.; Li, S.; Sun, B.; Huang, C.; Huang, K.; Zeng, Y.; Liu, C. Flexible Riser Tensile Armor Modelling Method and Application to Fatigue Analysis. J. Mar. Sci. Eng.2023, 11, 1500.
Zhang, N.; Li, S.; Sun, B.; Huang, C.; Huang, K.; Zeng, Y.; Liu, C. Flexible Riser Tensile Armor Modelling Method and Application to Fatigue Analysis. J. Mar. Sci. Eng. 2023, 11, 1500.
Abstract
In this paper, we present a new stress calculation method for flexible structures, particularly, the tensile armors, and apply it to flexible riser fatigue analysis. The method is based on a 3-dimensional curved bar theory. First, the tensile armor center line was described as a cylindrical helix curve, its bended curve length and bending migration length were derived and studied under different friction scenarios. Second, the tensile and bending stiffness was given with consideration of frictional hysteretic effect, and verified through FEA analysis results. Third, we presented the stress calculation formula for tensile armor under tension and bending load. All stress components are considered, including tensile, bending and shear stresses. Fourth, the method was benchmarked with published experimental results on a flexible prototype tension and bending tests, and comparisons showed general agreements. Fifth, the method is further applied to a 8” flexible riser for fatigue assessment and lifetime extension evaluation, and showed the flexible riser has sufficient remaining fatigue life, and is suitable to continue its service under the current operating conditions. Last, conclusions are drawn. It concluded that the presented tensile armor stress calculation method and modelling techniques are valid for flexible riser fatigue analysis. This method is time efficient, and can be implemented into other multi-scale models for riser dynamic analysis. It is also applicable to other similar helix structure stress analysis, such as wire ropes, submarine hoses, and subsea umbilicals.
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