Equidimensional fractal maps for indirect estimation of deformation damage in nonuniform aircraft alloys

This article describes the surface relief formation on Al single-crystal plates (sensors) with orientation {100}〈001〉 that were rigidly attached to weld specimens of aircraft alloy 2024 T351 during fatigue loading. Taking into account the nonuniform structure of the weld alloy, we located sensors in different zones of the weld specimens to receive information about the sites of strain localization and probability of destruction. The qualitative and quantitative information about the sensor relief was extracted by the online method automated on the basis of a stereomicroscope with a charge-coupled device (CCD) camera attached to a personal computer by a video adapter and frame-grabber card. The quantitative and qualitative relief parameters are shown to correlate with the deformation prehistory of the weld specimens. Panoramic views were created and used for fractal analysis of deformation relief. Spatial distributions of information fractal dimension on the sensor surface for different numbers of cycles were plotted in the shape of contour lines with equal values (equidimensional maps). Equidimensional maps for sufficiently large sensors allow us to find strain localization sites in specimens and monitor their evolution in an online regimen.