Creep analysis of steam turbine welded diaphragm

A procedure for the creep analysis of diaphragms is proposed that is based on the multi-grid finite element method, Rabotnov-type creep aging theory and the method of variable parameters of elasticity. Three-dimensional calculation models of the diaphragm are constructed and the peculiarities of its stress-strain state are found taking into account the reduced resistance to creep in welded joints. It is shown that the axial displacements of the joints of the diaphragm are 30% higher for the end guide vanes than those for the middle ones, while the stress intensity is twice as higher. The area of the elastic strain intensity maximum at the leading edge of the guide vanes moves, with consideration of creep, towards the welded joint area where their intensity reaches 2%.