Experimental-Numerical Validation Framework for Micromechanical Simulations

Abstract

A combined experimental-numerical framework is presented in order to validate computations at the microscale. It is illustrated for a flat specimen with two holes, which is made of cast iron and imaged via in situ synchrotron laminography at micrometer resolution during a tensile test. The region in the reconstructed volume between the two holes is analyzed via Digital Volume Correlation (DVC) to measure displacement fields. Finite Element (FE) simulations, whose mesh is made consistent with the studied material microstructure, are driven by measured Dirichlet boundary conditions. Damage levels and gray level residuals for DVC measurements and FE simulations are assessed for validation purposes.

Numerical modeling of ductile fracture at the microscale combined with X-ray laminography and digital volume correlation

“…This methodology, which is described in more details in Refs. [6,7,10], is a promising approach for getting a better understanding of nucleation, growth and coalescence mechanisms of heterogeneous microstructures for complex loading paths. By using DVC measurements as boundary conditions for FE simulations, this approach can also be used to calibrate nucleation and coalescence criteria and could therefore be an interesting way of feeding more physical macroscopic damage models used in material forming processes.…”

“…• Comparisons between experimental measurements and numerical simulations based on displacement fields and correlation residuals [7].…”

“…FIGURE 1. Schematic representation of the methodology coupling X-Ray laminography images, DVC and FE modeling [6,7].…”

“…An immerged approach is used hereafter, which means that voids are meshed and defined as a purely elastic material with very low Young's modulus with respect to the matrix. A sensitivity analysis showed that a ratio of 1000 between this modulus and that of the matrix was sufficient [7]. The properties of the matrix are deduced from stress/strain curves given in Ref.…”

“…[7], DVC provides displacement fields that can be interpolated and used as boundary conditions on the ROI boundaries. In that case, computations are carried out only on the ROI (see FIGURE 4).…”