船体结构S-N曲线选取方法

Research on selection method of S- N curve for hull structures

疲劳失效是船体结构破坏的主要模式之一。可采用S-N曲线法计算船体结构的疲劳寿命,S-N曲线的选取是该方法的关键内容之一。由于实际应用中可供选择的S-N曲线有限,无法全面涵盖所有类型的节点,规范中S-N曲线对于新型节点形式的适用性有待进一步研究。本文对S-N曲线的类型因子进行研究,提出采用热点应力集中系数选取S-N曲线的一般原则。并计算2种典型节点的应力集中系数,将其与规范值进行比较,发现计算值普遍小于规范值,按规范计算所得的疲劳寿命将趋于保守。

Fatigue failure is one of the main modes of hull structure′s damage, S-N curve method can be used for fatigue life calculation of hull structure, and selection of S-N curves is key content of this method. Because the S-N curves to be selected is limited actually, unable to cover all types of the nodes, the applicability of S-N curves in criterion for new node needs to be further studied. This paper studied the classification factor of the S-N curve, the general principle in selection of S-N curves used hot spot stress concentration coefficient is proposed. This paper computed stress concentration coefficient of two typical joints, and compared it to the recommended value of criterion. The computed value is smaller than the criterion value, fatigue life calculated according to criterion will tend to be conservative.