Material constant


Creep-fatigue interaction factor


Equivalent creep-fatigue interaction factor


Equivalent creep-fatigue life


Larson Miller parameter


Temperature of blade material

D c , i

Creep life fraction consumed

D f , i

Fatigue damage parameter

D c + f

Creep-Fatigue interaction damage parameter


Young’s Modulus of the material

N f

Number of stress cycles to failure

N f , i

Number of cycles to failure

N f , c + f

Number of cycles to creep-fatigue interaction failure

N i

Number of cycles accumulated

t f

Time to creep failure

t f , i

creep fracture life at same stress-temperature combination

t f , c + f

Time to creep-fatigue interaction failure

t f , c + f _ Re f

Time to creep-fatigue interaction failure at a reference point

t i

Time spent at a given stress-temperature combination

ε f

True fracture ductility

σ a

Nominal alternating stress amplitude

σ u

Ultimate tensile strength of the material