Digital image correlation of heterogeneous deformations in polycrystalline material with electron backscatter diffraction.

摘要

This work establishes the ability to conduct digital image correlation (DIC) investigations at varying length scales. DIC allows for a computational method of strain field measurements using multiple images to track random speckle patterns on material surfaces. The use of a powder silicon oxide speckle allows for high optical magnification correlation using conventional load frames. Self-assembling gold nanoparticles provide sub-micron resolution speckle patterns to study microstructure influences on deformation using scanning electron microscopy. The complex microstructure in aerospace grade aluminum and nickel-based superalloys, give rise to varied deformation fields, which can be studied using electron backscatter diffraction. Specimen preparation techniques, speckle patterns, and image correlation analysis are discussed. Experimental identification of strains at grain level can help validate computational crystal plasticity finite element models, which in turn provide better predictive computational models.