基于改进四峰谷值雨流计数法的船舶疲劳强度评估

Fatigue Strength Assessment of a Trimaran Based on Rain-flow Counting Method of Improved Four Peak-to-valley

考虑到在船舶时域疲劳强度评估中,对应力时间历程进行统计,雨流计数法对结果准确度有重要影响,针对常规四峰谷值雨流计数法的缺陷,提出一种改进四峰谷值雨流计数原则,同时考虑到时域法进行全海况船舶疲劳评估的耗时性,以改进频域谱分析法为基础,结合改进四峰谷值雨流计数法对某三体船进行疲劳强度评估,结果表明,改进谱分析法的评估结果与真解差距较小,可满足于实际工程计算需求。

In time domain fatigue strength assessment of ships the time history of stress should be counted,and the selection of a suitable rain-flow counting method is very important for the accuracy of the results.Aiming at the defects of the conventional rain-flow counting method of four peak-to-valley,a rain-flow counting principle of improved four peak-to-valley was proposed.Meanwhile,considering the time-consuming nature of the full sea state ship fatigue assessment by the time-domain method,the fatigue strength of a trimaran was assessed based on the improved frequency domain spectrum analysis method combined with the improved rain-flow counting of four peak-to-valley.The results showed that the evaluation results of the improved spectral analysis method are less different from the exact solution,which can meet the needs of practical engineering calculation.