S. Maraghechi 1* , J.P.M. Hoefnagels 1 , R.H.J. Peerlings 1 , M.G.D Geers 11 Dept. of Mechanical Engineering, Eindhoven University of Technology, the Netherlands

Small scales in-situ deformation measurements can provide rich field data of micro-structures, enabling theunraveling of complex micromechanics. In-situ micro-mechanical visualization capabilities, notably SEM,has played an important role in this field, in conjunction with full-field mechanical deformation measurementsuch as DIC. However, the non-trivial imaging procedure in an SEM introduces complicated artifacts in theimages (barrel distortion, drift, and so-called ‘jump’ artifacts), which reflect as large strain errors. Correctionalgorithms for some of these artifacts have been proposed in the literature with varying success, however, ageneric framework for dealing with all of these artifacts simultaneously is lacking.In this work, a general time-integrated GDIC framework based on hierarchical mapping functions isintroduced, which the specific purpose for correcting for the SEM imaging artifacts. Here, GDIC is extendedto quantify all SEM artifacts simultaneously with the micro-mechanical deformation fields, in order toguarantee high accuracy in the micro-mechanical strains. SEM artifacts are often deterministic, resultingfrom the imaging process. Therefore, the mapping functions used for regularization of the GDIC problemhave been defined in a mathematically consisted framework according to the hierarchical nature of thedistortions based on the physics of the SEM scanning process.This methodology has been verified on virtual images showing the effectiveness of the procedure and thehigh accuracy in quantifying all SEM artifacts alongside the mechanical deformation measurement. Inaddition, examples of SEM images captured during an in-situ micro-tensile test on steels and copper specimen are correlated by this method, demonstrating the robustness in practice.

ACKNOWLEDGEMENTSThe research leading to these results has received funding from the European Research Council under theEuropean Union's Seventh Framework Programme (FP7/2007-2013) / ERC grant agreement n° [339392].