Variable amplitude crack growth in notched specimens

Predictions of variable amplitude fatigue crack growth in notched tensile specimens at an elevated temperature and relative high loads were conducted. The predictions were based on constant amplitude fatigue data and mean crack growth rates were calculated. Crack closure levels were calculated by comparison of crack closure free experimental data obtained with the so called constant KI,max-method and nominal data. Also, numerical simulations of the closure level throughout the specimens were performed. Although experimental data showed rather large a scatter it was concluded that variable amplitude crack growth rates can be predicted with reasonable agreement using constant amplitude fatigue data. Also, crack growth rates cannot be predicted by LEFM in the inelastic notch affected zone, even if absence of crack closure is assumed.