船体结构在非线性波浪载荷作用下疲劳累积损伤计算

本文通过对非线性波浪弯矩循环所产生应力的雨流计数、独立性检验、线性回归显著性检验、方差齐性（Ｂａｒｔｌｅｔｔ）检验以及分布拟合和分布拟合检验，表明应力范围和平均应力相互不独立，且线性相关。应力范围的边缘分布可认为是Ｗｅｉｂｕｌｌ分布，平均应力在应力范围为一定值时的条件概率分布为正态分布，且其方差是齐性的。然后利用Ｇｏｏｄｍａｎ修正公式，引入影响船舶结构疲劳损伤计算的平均应力影响因子及其近似计算公式。

FATIGUE DAMAGE CALCULATION OF SHIP STRUCTURES ACTED BY NONLINEAR WAVE BENDING MOMENTS

The stress range and the mean stress produced by nonlinear wave bending moment acting on ship hull are obtained by means of rain-flow cycle counting. The independence test, significance test of the linear regression, the homogeneity test of variance (Bartlett), distribution fitting and its test are made. The results show that the stress range and the mean stress are linearly dependent, the marginal distribution of the stress range can be supposed Weibull distribution, the conditional probability of the mean stress is normal distribution and its variance is homogeneous. The stress range is modified by Goodman formula to involve the mean stress effect on fatigue life. A mean stress effect factor is introduced to involve the mean stress effect on the fatigue damage calculation of ship structures, and its approximate calculation formula is given at last.