The structural integrity of a component represents the aggregation of the critical conditions that the component must fulfill in order to be capable to efficiently carry service loads. Ageing aircraft is a technical term revealing that the aircraft has reached or it is about to reach the service time for which it has been initially designed for. Ageing aircrafts are prone to Widespread Fatigue Damage (WFD) or Multiple Site Damage (MSD). LTSM has developed an integrated FE code for the computation of multiple site damage evolution and the determination of inspection intervals for the maintenance of aircrafts. The code comprises the following two components:

• super-element methodology, and
• analysis of corner cracks and through-width cracks.

• using the equivalent crack length concept, and
• considering the stochastic nature of the phenomenon.

Simulation with super-elements.	Finite element analysis of a corner crack

Prediction of crack coalition.	Prediction of crack growth under service loads