In Situ Microscopic Investigation to Validate Acoustic Emission Monitoring

A novel experimental mechanics technique using Scanning Electron Microscopy (SEM) in conjunction with Acoustic Emission (AE) monitoring is discussed to investigate microstructure-sensitive mechanical behavior and damage of metals and to validate AE related information. Validation for the use of AE method was obtained by using aluminum alloy sharp notch specimens with different geometries tested inside the microscope and compared to results obtained outside the microscope, as well as to previously published data on similar investigations at the laboratory specimen scale. Additionally, load data were correlated with both AE information and microscopic observations of microcracks around grain boundaries as well as secondary cracks, voids, and slip bands. The reported AE results are in excellent agreement with similar findings at the mesoscale, while they are further correlated with in situ and post mortem observations of microstructural damage processes.