A materials model (constitutive equation) is developed for the purpose of obtaining greater realism in high-tempera lure fatigue analysis. Creep, relaxation, strain hardening, Bauschinger effect, cyclic shakedown, rate effects, and response to more complex loadings are some of the phenomena which this model simulates. Test data from thermal-mechanical fatigue tests verify its predictions quantitatively.

The model's form is an equation for the rate of nonelastic strain as a function of current stress, current temperature, and strain history. Its use in the design of turbine blades and vanes and other high-temperature structures is discussed. A multidimensional form is presented for application to finite element programs.