Two-scale modeling of microscopically based failure processes at early stage of damage of ferritic ductile iron

DIEGO O. FERNANDINO

Nantes

Conferencia; Fifth International Conference on Computational Modeling of Fracture and Failure of Materials and Structures; 2017

Ecole Centrale of Nantes and GeM Institute

In this work, a multi-scale analysis to study the early damage mechanics of ferritic ductile iron is introduced. The methodology combines numerical analysis and exhaustive experimental observations in both macro and micro scales. The multi-scale problem is modeled using the pre-critical regime of the Failure Oriented Multi-Scale Variational Formulation(FOMF)[1], which is implemented via a FE2 approach. Finite element analysis in the micro-scale is customized to account for plastic deformation and matrix-nodule debonding. Experiments in the micro-scale are used for microstructural characterization of the materialmechanical properties and the assessment of the micro-scale plasticity/damage mechanisms;experiments in the macro-scale provide the data to calibrate and validate the methodology.The multi-scale model is found eective for capturing the sequence of events and extent of the plasticity/damage mechanisms in the micro-scale as well as to infer, via inverse analyses, the parameters of the matrix-nodule debonding law (fracture energy and peak tensile stress), which cannot be estimated through experiments. Results allow to draw conclusions related to the applicability of the FOMF and the RVE sizing for non-linear damage analysis.Additionally, it allows to develop new insights for the better understanding of ductile iron damage micromechanisms at early stage of damage.