Given the field-observed surface cracks and poor surface flatness of the deck to U-rib welds, this study aims to quantify the effect of weld profiles on the fatigue performance of the deck to U-rib welds. Frist, typical geometric characteristics of the weld profile were obtained through statistical sampling. Second, a parametric study on the influence of the typical characteristics was performed, and the local surface mutation was indicated as the main factor contributing to stress concentration from the analysis results. Third, the power spectrum density method was proposed to extract the local surface mutation, which was quantified by the defined mutation value (M), and the relationship between M and the fatigue life was derived utilising FE and theoretical method. Finally, the process for fatigue assessment of the weld surface was proposed. The results show that (1) in the simplified modelling of the welds in OSDs, a combination of the quadratic function and the transition radius can be used to describe the weld profiles; (2) the local geometric mutation, such as surface defects, should be paid much attention to during the field inspection; (3) the derived functional relationship between the mutation value and the fatigue life can be used to evaluate the fatigue performance of welds with different weld profiles. Overall, this study contributes to our understanding of fatigue cracking at the deck to U-rib welds and establishes a quantitative framework for evaluating the fatigue performance of the welds considering the effect of the weld profile.

鉴于现场观察到的甲板到 U 肋焊缝的表面裂纹和较差的表面平整度，本研究旨在量化焊缝轮廓对甲板到 U 肋焊缝疲劳性能的影响。首先，通过统计抽样获得焊缝轮廓的典型几何特征。其次，对典型特征的影响进行了参数研究，分析结果表明局部表面突变是导致应力集中的主要因素。第三，功率谱密度的方法，提出了提取局部表面突变，这是由所定义的突变值（量化中号）和之间的关系中号并利用有限元和理论方法推导出疲劳寿命。最后，提出了焊缝表面疲劳评估的流程。结果表明：（1）在 OSD 中焊缝的简化建模中，可以使用二次函数和过渡半径的组合来描述焊缝轮廓；(2) 现场检查时应注意局部几何突变，如表面缺陷；(3) 导出的突变值与疲劳寿命的函数关系可用于评价不同焊缝剖面的焊缝疲劳性能。全面的，