Impact of micro-scale residual stress on in-situ tensile testing of ductile cast iron: Digital volume correlation vs. model with fully resolved microstructure vs. periodic unit cell

Tito Andriollo*, Yubin Zhang, Søren Fæster, Jesper Thorborg, Jesper Hattel

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review


The understanding of the mechanisms controlling deformation of ductile iron at the micro-scale and their coupling to the manufacturing conditions is still far from complete. In this respect, recent synchrotron-based studies have demonstrated that the thermal contraction mismatch between the graphite particles and the matrix during solid-state cooling leads to a complex residual stress state in the microstructure. To investigate its impact on the room-temperature tensile deformation, a computational-experimental analysis extendable to other similar composite materials is presented in this paper. First, a miniaturized specimen is loaded and imaged in-situ with X-ray tomography. Then, the microscale displacement is reconstructed using digital volume correlation (DVC) and used to prescribe the boundary conditions in a finite element model of the full microstructure between two cross-sections. The model predictions at both the macroscale – tensile force and lateral contraction – and the microscale – strain field – are compared to the corresponding experimental and DVC-based data for several choices of the initial stress state, particles’ mechanical behavior and strength of the particles-matrix interface. It is proved that the micro-scale residual stress and a low interface strength are the key to explain the early stages of the tensile deformation of ductile iron. Finally, it is shown that a simple unit cell model of the microstructure would lead to significantly different results, thus demonstrating the superior accuracy and robustness of the present approach.
Original languageEnglish
JournalJournal of the Mechanics and Physics of Solids
Pages (from-to)714-735
Publication statusPublished - 2019


  • In-situ test
  • Digital volume correlation
  • Cast iron
  • Composite
  • Residual stress

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