螺旋条带局部变形对柔性立管弯曲响应的影响

Effect of local deformations of helical strips on bending behavior of unbonded flexible risers

推导出非黏合柔性立管弯曲时螺旋条带曲率和挠率的变化量,采用能量法考虑了这一局部变形对螺旋层弯矩-曲率关系和弯曲刚度的贡献,并基于此建立了柔性立管弯曲响应分析的理论模型.算例分析表明:条带的局部变形对立管完全滑移刚度的影响较大,应在分析时予以正确考虑;将理论分析与实验测试的结果进行了对比,二者符合较好;条带的局部变形还将引入相应的应力成分,采用梁理论对此进行了计算,与商用软件的结果对比显示其对应力的影响较大.

Expressions were derived for the bending and torsion increments of helical strips as the unbonded flexible riser was exposed to a constant bending curvature. With energy approach, the contri- bution of these local deformations of individual helical strips to the bending moment versus curvature relationship and bending stiffness of helical layers was included. Analytical formulations were then presented to determine the bending behavior of flexible risers. Case study shows that the inclusion of the local deformations of individual helical strips significantly influences the full-slip bending stiffness and should be considered in the analysis. The theoretical results are compared with the experimental data from the available literature and encouraging correlations are found. The stress components in- troduced are calculated with the simple beam theory. The comparison of analytical and commercial software results shows that these components play an important part in the total stress.