1. Principle of forecasting

The predictive calculation of the service life of a mechanical system or component, used in real-life conditions, is based on four elements:

• knowledge of the loading (or stress) undergone (figures 1 a and b). Figure 1 a shows the definition of measurement points over time (with a predefined constant time step Δt). Figure 1 b is a reminder of the quantities considered later;

• an endurance law (often based on the Wöhler curve) (figure