A method to identify vortex-induced forces and coefficients from measured strains of a Steel Catenary Riser (SCR) undergoing vessel motion-induced Vortex-induced Vibration (VIV) is proposed. Euler–Bernoulli beam vibration equations with time-varying tension is adopted to describe the out-of-plane VIV responses. Vortex-induced forces are reconstructed via inverse analysis method, and the Forgetting Factor Least Squares (FF-LS) method is employed to identify time-varying vortex-induced force coefficients, including excitation coefficients and added mass coefficients. The method is verified via a finite element analysis procedure in commercial software Orcaflex. The time-varying excitation coefficients and added mass coefficients of an SCR undergoing vessel motion-induced VIV are investigated. Results show that vessel motion-induced VIV is excited at the middle or lower part of the SCR and in the acceleration period of in-plane velocity, where most of the excitation coefficients are positive, while during the deceleration period, the excitation coefficients becomes too small to excite VIVs. Parameter γ [1] has strong correlation with excitation coefficients. In addition, time-varying tensions contribute significantly to the variations of added mass coefficients under the condition that the ratio of dynamic top tension to pretension exceeds the range of 0.7–1.3. Moreover, chaotic behaviors are observed in vortex-induced force coefficients and are more evident with the increase of vessel motion velocity. This behavior may attribute to the randomness existing in in-plane velocity and its coupling with out-of-plane vibrations.

提出了一种方法，该方法从经受了容器运动引起的涡流诱发振动（VIV）的钢悬链提升管（SCR）的测量应变中识别涡流引起的力和系数。采用时变张力的Euler–Bernoulli梁振动方程来描述面外VIV响应。通过逆分析方法重建涡激力，并采用“遗忘因子最小二乘法”（FF-LS）识别随时间变化的涡激力系数，包括激振系数和附加质量系数。该方法通过商业软件Orcaflex中的有限元分析程序进行了验证。研究了随船舶运动引起的VIV的SCR的时变激励系数和附加质量系数。结果表明，由船舶运动引起的VIV在SCR的中部或下部以及在平面内速度的加速期内被激励，其中大多数激励系数为正，而在减速期间，激励系数也变得小到可以激发VIV。参数γ[1]与激励系数有很强的相关性。此外，在动态顶部张力与预张力之比超过0.7-1.3的条件下，随时间变化的张力会显着影响附加质量系数的变化。此外，在涡流引起的力系数中观察到混沌行为，并且随着血管运动速度的增加而变得更加明显。这种行为可能归因于平面内速度存在的随机性及其与平面外振动的耦合。