Study of localized strain at micro-, meso- and macrolevels in AA2024 alloy by data of acoustic emission, surface strain mapping and strain gauging

The relevance of a multilevel consideration of deformation and fracture is caused by the variety of deformation processes, their interaction and change of their defining role at various loading stages. From the experimental research viewpoint the multilevel consideration can be achieved only through the use of gauges of various type and operation principle. We combine Digital Image Correlation (DIC) method for strain estimation and acoustic emission (AE) for investigating strain and fracture patterns at various scale levels. Quantitative analysis of experimental data was performed by constructing diagrams (dependencies) of shear strain intensity as functions of the deformation degree (loading time). It is shown that the increase of strain intensity happens at the moment when a macro shear-band is formed. Also, patterns of localized deformation were simulated with use of the ANSYS finite element package. A good qualitative correlation is observed between numerical data and surface strain mapping. For the characterization of localized strain processes, the dependencies of rate of AE events versus loading time were analyzed, since they appear to be the most sensitive to the change of the principal scale of plastic deformation.