Method for estimating stress intensity factors and method for calculating associated service life

A method for estimating (100) the stress intensity factor in a numerically modeled part, within the context of a fatigue crack propagation model, implemented by a system (10) comprising a data processing unit (12), the method for estimating (100) comprising the following steps:

• (E2):
• obtaining from a numerical model of the part to be analyzed (20), a plurality of values simulated at different points of the part to be analyzed (20),
• said plurality of simulated values comprising, for different simulated propagation increments a three-dimensional crack which appears on the numerical model of the part, a set of simulated values of the stress intensity factor at associated points, the position of these points, and data relating to the cracked surface of the crack,
• (E3):
• determining, for each propagation increment and for the set of simulated values therefor, a converted amplitude value of the equivalent global effective stress intensity factor corresponding to that of a plane crack with a straight front and a converted length of the equivalent crack considered, said converted values being determined by equalizing the energy dissipated in the three-dimensional crack of the numerical model and the energy dissipated in the crack of a standard model of a plane crack with a straight front, the energies themselves being determined according to the stress intensity factors,
• (E4):
• Interpolating converted amplitude values of equivalent global effective stress intensity factor between two successive converted crack lengths,
• (E5):
• Storing the converted amplitude values of equivalent global effective stress intensity factor thus interpolated with the associated crack lengths.