局部凹陷和偏心对接对海洋立管疲劳寿命影响的数值分析

针对涡激振动导致的干涉碰撞及焊接时产生的偏心会降低海洋立管疲劳寿命的问题,用S-N法计算局部凹陷、偏心对接分别作用以及二者共同作用下海洋立管的疲劳寿命.在偏移位置、局部凹陷位置和过渡区域长度确定的情况下,偏移幅值和局部凹陷幅值越大,过渡区域的应力越大,寿命越小;在偏移幅值、局部凹陷幅值和过渡区域长度确定的情况下,过渡区域距海洋立管中部越近对过渡区域的应力及寿命影响越大.

Numerical analysis on effect of local depression and eccentric butt on marine riser fatigue life

As to the issues that marine riser fatigue life can be reduced by interference and collision generated by vortex induced vibration and weld induced eccentricity, S N method is used to calculate the fatigue life of a marine riser under the effects of local depression and/or eccentric butt. When the eccentricity location, local depression location and length of transition region are determined, the larger amplitudes of eccentricity and local depression lead to the larger stress levels in the transition region and shorter life. When the eccentricity amplitude, local depression amplitude and length of the transition region are determined, the smaller distance between the transition region and middle part of marine riser leads to the stronger effect on both stress in the transition region and marine riser life.