Extrapolation of load histories and spectra

In fatigue life assessments, both the material properties and the load characteristics are essential parameters. The life of a component can be experimentally found by performing fatigue tests. In order to get reliable predictions of the life in service, the tests should be performed using variable amplitude loadings that are representative for the service loads. This paper concentrates on the problem of extrapolating a measured load history to a longer time period, for example to a full design life. Using statistical extreme value theory, a new method for extrapolation in the time domain is presented. The extrapolated load spectrum, obtained from the extrapolated time signal, is compared to the result using a method for extrapolating the rainflow matrix.