In the world of shipbuilding, innovation is key to staying ahead, and one of the latest advancements making waves is the use of laser-welded metal sandwich composite structures. These structures, known for their strength and lightweight properties, are increasingly being adopted in the maritime industry. However, as with any new technology, there are challenges to overcome. Jun Yang, a researcher at the Zhenjiang Branch of Institute for Maritime Transport Equipment Safety (Ningbo) Co. Ltd., has been delving into one such challenge: the fatigue failure of these structures due to laser welding.
In a recent study published in ‘Hanjie xuebao’ (translated to ‘Acta Armamentarii’ or Journal of Ordnance Materials), Yang and his team conducted four-point bending fatigue tests on I-type metal sandwich plates. Their goal was to understand the crack initiation and propagation process in these structures. The results were revealing. The team found that the fatigue source region is located in the heat-affected zone of laser welding, where cracks first start and then spread along the web and the panel. “The fatigue sources are generated in the laser welding area of multiple webs and lower panels of sandwich plates,” Yang explained. “However, due to the difference in initial defects in laser welding of different webs, the crack propagation speed is different.”
The study also involved numerical simulation based on the cohesive force model theory to further reveal the crack propagation behavior under fatigue load. The results showed that for the sample of I-type metal sandwich plate studied, the propagation area of different cracks presents a stepped form.
So, what does this mean for the maritime industry? Understanding the fatigue failure mechanism of these structures is crucial for their safe and effective use in shipbuilding. By identifying the areas where cracks are most likely to initiate and propagate, shipbuilders can take preventive measures to enhance the durability and longevity of these structures.
Moreover, this research opens up opportunities for further innovation. As Yang puts it, “The results of this study can provide a reference for the design and application of laser-welded metal sandwich composite structures in the maritime industry.” This could lead to the development of new welding techniques or materials that are less prone to fatigue failure, further enhancing the performance and safety of ships.
In conclusion, while laser-welded metal sandwich composite structures present some challenges, they also offer significant opportunities for the maritime industry. With ongoing research and innovation, these structures could become a mainstay in shipbuilding, contributing to safer, more efficient, and more sustainable maritime operations.