基于损伤力学和XFEM的舰船蒸汽轮机叶片裂纹扩展研究

As the core component of marine steam turbine, the fatigue life of blade in complex conditions has been a concern. Most traditional life prediction methods are based on the maximum stress or strain position of the blade during the working process. The influence of the damage accumulation on the inherent properties of the material is not considered in the methods which are based on the empirical formula, and the crack initiation life and the crack propagation life of the blade are not described completely. Based on the basic theory of damage mechanics, this paper deduces the formula of low-cycle fatigue life of blade which considers the actual nonsymmetry operating condition of turbine blade; by introducing the concept of average stress, the expression of the relationship between damage and cycle times is proposed. At the same time, based on the finite element analysis software ABAQUS, XFEM method is used to simulate the crack growth simulation and the low-cycle fatigue life analysis of the blade, and the results are compared with the theoretical calculation results. The results show that the proposed calculation method of low cycle fatigue life based on damage mechanics coincides well with the finite element method of blade crack propagation analysis, which has a certain value for the prediction of life span of steam turbine blades and other engineering structures.