Establishment of pipe FEA model and influence of structural symmetry on its residual stress

At present, there is barely any research on the residual stress of the pipe welded by dissimilar metals in the drive shaft of the controllable pitch propeller. As the core power elements of the controllable pitch propeller, reliability of the pipe is particularly important. Based on the finite element software ANSYS, the thermal-elastoplastic finite element model for the analysis of the welding temperature field and stress field of the outer pipe was established with a four-ellipsoid heat source model to simulate the welding heat input. The model was verified by experiments. On this basis, the influence of the simplification method of the long weld FE model and the symmetry of the welded structure on the residual stress of the pipe is studied. The research results show that, on the basis of ensuring the calculation accuracy, the calculation speed of the simplified pipe finite element model is 8 times that of the original model. The residual stress of the pipe with asymmetrical structure is obviously greater than that of the pipe with symmetrical structure in numerical value. To a certain extent, the pipe with asymmetrical structure can reflect the residual stress distribution at the weakest position of the pipe with symmetrical structure.