Statistical characteristics of propagation of small fatigue cracks in smooth specimens of aluminium alloy 2024-T3

In Situ Microscopic Investigation to Validate Acoustic Emission Monitoring

“…The challenge, however, is that damage is a multiscale process particularly when the incubation and initiation phases are concerned, as shown for example in recent investigations on crack formation in metals undergoing fatigue loading [1][2][3]. Detailed considerations of the material's actual microstructure are shown to be crucial to their mechanical behavior during loading, as reported recently in steel [4], aluminum [5][6][7][8][9][10][11], magnesium [12][13][14][15][16], and titanium alloys [17,18] among others [2,3,19,20]. These materials span a range of crystalline structures and contain a number of initial defects from material processing [11], some of which include voids, precipitates, dislocations, and microcracks that can propagate and lead to damage at multiple length scales.…”

Microstructurally-dependent model for predicting the kinetics of physically small and long fatigue crack growth

“…The observation of the surface crack growth was performed in the plane LT, that is, the crack size l corresponded to its projection onto the T-axis. As noted in [20], the crack depth-to-half surface crack length ratio was, on the average, equal to unity in the range of l from 0.02 to 1.5 mm. Thus, it can be considered as semi-circular, at least within the PSC.…”

“…12). In addition to the grain size, [20] contains only the data on yield stress r 0:2 ¼ 322 MPa. Therefore, the parameter r p ffi 0:75r 0:2 ¼ 240 MPa was taken for the calculation.…”

“…Thus, a comparison was made between the LC growth curves obtained experimentally and those calculated according to the given model. To test the validity of calculation of PSC growth curves, experimental data on the small surface crack growth in specimens of Ti-6Al-4V titanium alloy [19] and 2024-T3 aluminum alloy [20] were used.…”

“…The initial data for the calculation were taken from [20]. The microstructure of the investigated alloy 2024-T3 is shown in Fig.…”