Issues related to the constitutive modeling of ni-based single crystal superalloys under aeroengine certification conditions

This paper presents a constitutive modeling approach (the Polystar model) used to compute the viscoplastic behavior and the durability of high pressure turbine blades and vanes of aeroengines during complex thermomechanical histories typically encountered during certification procedures. This model is based on internal variables representing explicitly the microstructure evolutions occurring during very high temperature non-isothermal loading (e.g., dissolution/re-precipitation of the strengthening phase, dislocation recovery mechanisms, etc.) in a crystal viscoplasticity modeling framework. This article shows that the development of such a modeling tool requires a good characterization of fast microstructure evolutions, as well as in-service-type experiments (using burner rigs) able to reproduce the complex thermomechanical loading spectra. The capabilities of the model are illustrated, as well as its potential industrial applications and further developments are commented.