Head, Deutsche Versuchsanstalt für Luft-und Raumfahrt, Institut für Festigkeit, Mulheim (Ruhr),
Pages: 19 Published: Jan 1970
On the basis of a gust-load distribution, evaluated by applying level crossing-counting method, an 8-step program test and tests with a random sequence of stress cycles were performed. The results of these tests are compared with the results of tests with a random sequence of maxima and minima. The latter are based on a distribution of maxima and minima, which were derived from the gust-load distribution splitted in several stationary Gaussian processes. In further tests, ground-air-ground cycles were included in the study. Programmed and randomized flight-by-flight tests were compared.
The results of the study revealed that in the case of steady mean stress and the applied conditions program loading overestimates life by a factor of about 6. In case of flight-by-flight tests, however, the load-time history (either programmed or randomized) seem to be unimportant.
random processes, load (forces), fatigue (materials), digital techniques, computer programs, flight tests, crack propagation, tests, evaluation
Paper ID: STP32042S