基于缺口应力法的IIW多轴疲劳准则分析

焊接接头的多轴疲劳强度评估是领域内的复杂课题.结合缺口应力法,利用ⅡW多轴疲劳准则对已公开发表的文献中的多轴疲劳试验数据进行了重新评估.结果表明,缺口应力系统下的比例加载与非比例加载数据点重合性较好;ⅡW推荐的单轴疲劳评估S-N曲线不适用于多轴疲劳评估,循环次数在1×104 ~1×105范围内时,可能得到偏危险的评估结果;而高于1×105次时,评估结果过于保守.基于此,拟合得到了存活率P_s=97.7%的S-N评估曲线,其疲劳等级FAT=430 MPa,斜率m=5.8,同时适用于比例加载与非比例加载,可为工程焊接结构疲劳寿命预估提供参考.     

滚装船滚装通道系统艉跳板结构强度有限元分析

近年来,由于滚装船具有装卸效率高、减少船舶靠泊时间、作业时无需起重设备等优点,对滚装船相关的研究更加受到关注。我国生产与出口的车辆滚装船数量位居世界前列,是重要的海上运输工具。艉跳板作为联系滚装船与码头的重要通道设备,在船舶靠泊时,起到连接与承载的作用。因此跳板的稳定性与安全性将直接关系到滚装船滚装通道系统的稳定性与安全性。为确保某滚装船滚装通道系统研制项目的艉跳板结构安全,参照《船舶与海上设施起重设备规范》（2007）、《钢质海船入级建造规范》（2022）的相关内容,采用有限元软件MSC/PATRAN和MSC/NASTRAN建立了整个艉跳板结构模型,并对码头作业工况、放置工况和操作工况3种作业形式共7种工况进行强度校核分析。结果表明：其均满足规范中许可使用的应力衡准要求,艉跳板结构强度满足要求,对滚装船艉跳板的结构设计问题具有一定的借鉴意义。     

Research on stress concentration factor of tube joints under pure bending and torsion loading

For fatigue strength design and evaluation as well as for multiaxial fatigue tests analysis of welded structures, the stress concentration factor(SCF) at the weld must be known. In the present study, two common models of multiaxial fatigue tests, tube-plate(TP) model and tube-tube(TT) model are selected as the research objects. SCFs of the two models with various geometric parameters under pure bending and pure torsion loading have been investigated by conducting a series of three-dimensional(3 D) finite element models based on linear elasticity theory. The effect of weld width(w), plate thickness(t), weld toe notch radius(r), and reinforcement angle(θ) on SCF is assessed. The quadratic parametric equations based on t/r are proposed to predict SCFs of the two models, which reveal satisfactory accuracy.