【摘要】 激光焊金属夹芯复合结构因其优良性能在船舶领域应用日益增多，然而与传统焊接工艺相比，激光焊会在面板与腹板之间引入更复杂的焊接缺陷，严重影响结构的疲劳性能.采用Ⅰ型金属夹芯板为研究对象，进行了四点弯曲疲劳试验，对试验结果开展了宏观和扫描电镜分析，获取裂纹的萌生及扩展过程；基于内聚力模型理论开展数值模拟，进一步揭示Ⅰ型金属夹芯板在疲劳载荷作用下的裂纹扩展行为.结果表明，疲劳源区位于激光焊的热影响区，裂纹在此处首先萌生，之后沿着腹板和面板同时扩展；在夹芯板多个腹板与下面板的激光焊区域都会产生疲劳源，但由于不同腹板激光焊初始缺陷的差异性导致裂纹扩展的速度不同，对于Ⅰ型金属夹芯板试样，不同裂纹的扩展区域呈现阶梯形式.更多还原

【Abstract】 Laser-welded metal sandwich composite structures are increasingly used in the field of ships because of their excellent properties. However, compared with the traditional welding process, laser welding will introduce more complex welding defects between the panel and the web, which will seriously affect the fatigue properties of the structures. The four-point bending fatigue test was carried out with an Ⅰ-type metal sandwich plate as the research object, and the test results were discussed by macroscopic analysis and scanning electron microscopy to obtain the crack initiation and propagation process. Based on the cohesive force model theory, numerical simulation was carried out to further reveal the crack propagation behavior of an Ⅰ-type metal sandwich plate under fatigue load. The results show that the fatigue source region is located in the heat affected zone of laser welding, where the cracks first start and then spread along the web and the panel. Fatigue sources are generated in the laser welding area of multiple webs and lower panels of sandwich plates. However, due to the difference in initial defects in laser welding of different webs, the crack propagation speed is different. For the sample of Ⅰ-type metal sandwich plate studied in this paper, the propagation area of different cracks presents a stepped form.更多还原