基于非线性设计波的船体结构强度直接计算研究

针对规范公式不适用于小方形系数Cb0.6的船舶以及线性设计波法不能反映波浪载荷非线性特征的情况,使用非线性设计波法研究了一艘小方形系数船的波浪载荷长期预报极值和波浪载荷与波高非线性变化规律,给出了非线性设计波参数的选取办法。根据参数,用非线性设计波法计算了船舶的波浪附加弯矩,并与线性设计波和规范公式两种方法得到的波浪附加弯矩进行了比较分析。分析结果表明,非线性设计波法能够反映出波浪幅值较大时波浪载荷随波高非线性变化的规律,以及中拱、中垂状态下舯剖面波浪附加弯矩的非对称特征,较线性方法更为合理。

Nonlinear design wave method in direct calculation of ship structure

For ships with block coefficient Cb < 0.6 the formula in rules is not applicable, and the traditional linear design wave method cannot consider the nonlinear effect of wave induced load. In this paper, the parameters of the nonlinear design wave are determined after the long term prediction of the wave induced vertical bending moment and the study of the nonlinear relation between the bending moment and the wave height. The study shows that nonlinear design water method takes into account the asymmetry of the wave induced vertical bending moment and its nonlinear relation to the wave height.