深海非粘结柔性立管简化模型数值分析及实验研究

摘要

A new simplified model is proposed for the analysis of deepwater unbonded flexible risers,in which the influence factors of flexible risers’tensile,torsion and rigidity are discussed. The unbonded flex⁃ible riser is suitable for rough deep-sea conditions due to its structural features,i.e. small rigidity,light in mass,strong corrosion resistance and anti-fatigue performance. However,the numerical simulation analy⁃sis of the unbonded flexible riser are confronted with a number of challenges resulted from its strong nonlin⁃ear characteristics in the friction and contact between different layers of the unbonded flexible riser. Thus, it is difficult to guarantee both accuracy and efficiency when evaluating an unbonded flexible riser model. Aiming at this problem,a new simplified model is proposed by employing a simplified beam and shell ele⁃ment model and considering the axial elastic modulus of the carcass and pressure armour. In order to vali⁃date the proposed model,the experimental data are compared with the numerical solution,and the results show that the simplified model does not only reduce the computation cost,but also agrees well with the ac⁃tual constitutive relation of the flexible riser.%　　非粘结柔性立管具有弯曲刚度小、质量轻、耐腐蚀以及抗疲劳等特点，适用于深海恶劣的海况。然而由于非粘结柔性立管层与层之间的摩擦、接触等诸多强非线性特性，使得其数值模拟分析面临众多挑战，很难同时保证分析模型的精度和效率。提出一个新的非粘结柔性立管简化模型，在考虑摩擦和接触等非线性特性，以及骨架层和抗压层的沿轴向的弹性模量的条件下，运用梁单元和壳单元简化了建模。实验研究的拉伸、扭转、弯曲刚度结果与新建简化模型计算结果的对比分析，验证了所建简化模型的可靠性。研究表明，新的简化模型不仅能节省计算时间，而且更加接近柔性立管的实际本构关系和实验结果。