Residual stress analysis on blade-shaped welding structure of outer oil pipe for controllable pitch propeller

Controllable Pitch Propeller (CPP) is a specialized propulsion device for ships, where the oil pipe is the core power component. Once the support bar welding joint attached to its surface breaks, it can lead to serious safety hazards. In the paper, finite element method was used to simulate the welding process of the outer oil pipe and the blade-shaped support bar, and the reliability of the model was validated through experiments. Based on this model, three different welding structures - segmented interval welding, concentrated segmented welding, and full welding - as well as different support bar materials were studied. The results show that the maximum residual stress generated by segmented interval welding was approximately 5.7% lower than that of concentrated segmented welding, with little difference between concentrated segmented welding and full welding. The maximum residual stress generated by welding outer oil pipes with Q355B material support bars was approximately 6.53% lower than that of QAL9-4, which provides a reference for pipe welding.