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

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

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
Volume125
Pages (from-to)714-735
ISSN0022-5096
DOIs
Publication statusPublished - 2019

Keywords

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

Cite this

@article{253b6f83db9a49afa1722230133c1e83,
title = "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",
abstract = "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.",
keywords = "In-situ test, Digital volume correlation, Cast iron, Composite, Residual stress",
author = "Tito Andriollo and Yubin Zhang and S{\o}ren F{\ae}ster and Jesper Thorborg and Jesper Hattel",
year = "2019",
doi = "10.1016/j.jmps.2019.01.021",
language = "English",
volume = "125",
pages = "714--735",
journal = "Journal of the Mechanics and Physics of Solids",
issn = "0022-5096",
publisher = "Pergamon Press",

}

TY - JOUR

T1 - 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

AU - Andriollo, Tito

AU - Zhang, Yubin

AU - Fæster, Søren

AU - Thorborg, Jesper

AU - Hattel, Jesper

PY - 2019

Y1 - 2019

N2 - 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.

AB - 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.

KW - In-situ test

KW - Digital volume correlation

KW - Cast iron

KW - Composite

KW - Residual stress

U2 - 10.1016/j.jmps.2019.01.021

DO - 10.1016/j.jmps.2019.01.021

M3 - Journal article

VL - 125

SP - 714

EP - 735

JO - Journal of the Mechanics and Physics of Solids

JF - Journal of the Mechanics and Physics of Solids

SN - 0022-5096

ER -