CONSTITUTIVE MATERIAL FORMULATIONS AND ADVANCED LIFE ASSESSMENT METHODS FOR SINGLE CRYSTAL GAS TURBINE BLADES

摘要

Constitutive models for single crystal superalloys have been developed for the past fifteen years in response to the increasingly wider use of these materials to manufacture industrial and aerospace gas turbine blading. A number of model formulations are now available that aim to predict correctly the deformation behaviour at loading conditions similar to those experienced in service. Some of the most relevant work in this field is reviewed in this paper. In engineering practice, the complexity of the material models used depends on the required level of accuracy and the ability to effectively perform computationally intensive FE analyses, due to the complex geometry of a cooled blade. However, it is argued that a constitutive formulation should take into account various features of the microstructure to predict correctly the effect of heterogeneities in the material that can be critical to the life of a component. Certain key aspects in the design assessment of cooled blades are also discussed, in particular the implications of the choice of constitutive models in the blade design procedure.