Abstract:

ESDU 92030 discusses the different propagation behaviour of short and long cracks; short cracks often do not display a threshold value of stress intensity factor range and propagate at higher rates than long cracks. The difficulties of calculating the stress intensity factor for short cracks are explained. Experimental data extracted from the literature for crack growth rate in air under constant amplitude loading are presented graphically against stress intensity factor range for 9 alloys (2024, 2090, 2124, 7010, 7075, 8090, 8091, RR58, an aluminium-lithium alloy) and in vacuum and nitrogen for 7075. All the curves are derived from a number of tests except for those 2124 for which data are for individual cracks. Details of the alloy, heat treatment and mechanical properties are given, and the experimental arrangement for each set of data is indicated. For all alloys except 7010 and 7075, data for both short and long crack growth are compared, and for 2090 the effect of stress ratio variation from 0 to -2 is shown.