Abstract: A method of determining material constants of a hardened metal object being exerted to load cycles, and a method of indicating fatigue damage rate of a hardened metal object in relation to load cycles, N, exerted on the hardened metal object, wherein material dependent constants of the hardened metal object are determined according to the method of determining material dependent constants of the hardened metal object. Methods for indicating fatigue and predicting life of a metal object are disclosed.

Abstract: A method for indicating fatigue damage rate of a hardened metal object in relation to load cycles, N, exerted on the hardened metal object, wherein the hardened metal object presents a temperature essentially corresponding to the operating conditions of the hardened metal object is disclosed. It comprises calculating the fatigue rate based on an effective activation energy parameter for the dislocation climb process, Q, shear stress amplitude, T, the absolute local temperature of the hardened metal object, T, and load frequency, f. Methods for indicating fatigue and predicting life of a metal object are disclosed.

Abstract: A method of determining material constants of a hardened metal object being exerted to load cycles, and a method of indicating fatigue damage rate of a hardened metal object in relation to load cycles, N, exerted on the hardened metal object, wherein material dependent constants of the hardened metal object are determined according to the method of determining material dependent constants of the hardened metal object. Methods for indicating fatigue and predicting life of a metal object are disclosed.

Abstract: The present invention concerns a method of calculating the expected life of a hardened metal object in relation to a number of fatigue load cycles exerted on the hardened metal object. The method comprises determining the development of microstructural deterioration as a function of fatigue exposure time, deriving therefrom an equation for the development of a Fatigue Damage Index as a function of fatigue exposure time and relating this equation to a known critical value of the Fatigue Damage Index that leads to material failure. The present invention also provides a method of calculating the remaining life of a hardened metal object subjected to fatigue loading.

Abstract: A method for indicating fatigue damage rate of a hardened metal object in relation to load cycles, N, exerted on the hardened metal object, wherein the hardened metal object presents a temperature essentially corresponding to the operating conditions of the hardened metal object is disclosed. It comprises calculating the fatigue rate based on an effective activation energy parameter for the dislocation climb process, Q, shear stress amplitude, T, the absolute local temperature of the hardened metal object, T, and load frequency, f. Methods for indicating fatigue and predicting life of a metal object are disclosed.