船体结构屈服强度可靠性分析

Reliability analysis of yielding strength of ship structures

通过短期海况的时间历程模拟,基于有限元法直接计算船体结构应力,得到短期海况下的结构单元米泽斯应力的时间历程及短期分布,进而得到单元米泽斯应力的长期分布和基于序列统计原理的极值分布.考虑到材料屈服极限和模型不确定性,建立了屈服强度可靠性分析的极限状态方程,给出了一种基于米泽斯应力的船体结构屈服强度可靠性分析方法.算例结果表明:结构单元的短期米泽斯应力符合威布尔分布,而基于序列统计原理的米泽斯应力极值分布符合对数正态分布.

Through the time domain simulation of the short term sea state and the direct calculation of the ship structural stress, the Mises stress response history of the structural elements were calculated, and the distribution of the Mises stress of the structural elements in the short term sea state were obtained. The long term distribution of the Mises stress was computed and the extreme value distribution was achieved by using the series stochastic theory. In view of the uncertainties of the yielding strength of the material and the model, the limit state function for the reliability analysis of the yielding strength was established. A reliability analysis method for the ship structural yielding strength was given based on the Mises stress. The example shows that the short term distribution of the Mises stress obeys the Weibull distribution, and the extreme yalue distribution achieved by using the series stochastic theory obeys the log-normal distribution.