An examination of local strain fields evolution in ductile cast iron through micromechanical simulations based on 3D imaging

TL;DR

This study compares digital volume correlation and finite element methods to analyze local strain evolution in ductile cast iron using 3D imaging, highlighting the accuracy and limitations of each approach.

Contribution

It introduces a micromechanical simulation framework based on 3D imaging data to evaluate local strain fields in nodular cast iron.

Findings

Macroscopic strains are accurately predicted

Good agreement in one specimen's local strains

Discrepancies observed in the second specimen's strains

Abstract

Microscopic digital volume correlation (DVC) and finite element precoalescence strain evaluations are compared for two nodular cast iron specimens. Displacement fields from \textit{in-situ} 3D synchrotron laminography images are obtained by DVC. Subsequently the microstructure is explicitely meshed from the images considering nodules as voids. Boundary conditions are applied from the DVC measurement. Image segmentation-related uncertainties are taken into account and observed to be negligible with respect to the differences between strain levels. Macroscopic as well as local strain levels in coalescing ligaments between voids nucleated at large graphite nodules are compared. Macroscopic strain levels are consistently predicted. A very good agreement is observed for one of the specimens, while the strain levels for the second specimen presents some discrepancies. Limitations of the modeling and numerical framework are discussed in light of these differences. A discussion of the use of strain as coalescence indicator is initiated.