On the choice of parameters in the phase field method for simulating crack initiation with experimental validation

Abstract

International audienceThe phase field method is a versatile simulation framework for studying initiation and propagation of complex crack networks without dependence to the finite element mesh. In this paper, we discuss the influence of parameters in the method and provide experimental validations of crack initiation and propagation in plaster specimens. More specifically, we show by theoretical and experimental analyses that the regularization length should be interpreted as a material parameter, and identified experimentally as it. Qualitative and quantitative comparisons between numerical predictions and experimental data are provided. We show that the phase field method can predict accurately crack initiation and propagation in plaster specimens in compression with respect to experiments, when the material parameters, including the characteristic length are identified by other simple experimental tests

Large-scale simulations of quasi-brittle microcracking in realistic highly heterogeneous microstructures obtained from micro CT imaging

“…We again observe very complex micro cracking patterns, but the morphology is different from the tensile test: in this case, the microcracks are roughly aligned with the direction of the load, while in the tensile test they propagate in direction perpendicular to the load. This is in agreement with other observations in more simple heterogeneous quasi-brittle samples [19].…”

Initiation and propagation of complex 3D networks of cracks in heterogeneous quasi-brittle materials: Direct comparison between in situ testing-microCT experiments and phase field simulations

“…This explains that the obtained g c (1.8 N/m) is larger than the one measured in the previous study of Romani et al (2015) of about 1.4 N/m. The increased strength may also induce a larger critical stress s c , which is associated with a smaller process zone length ℓ, (according to the analysis in Nguyen et al, 2016a). Indeed ℓ was found to be 0.1 mm in Romani (2013) and is now identified to be four times smaller.…”

“…It has been shown (see e.g Nguyen et al, 2016a;Amor et al, 2009;Kuhn et al, 2015;Benallal and Marigo, 2007) that ℓ is related to other material parameters and then should be identified experimentally as such. In Section 4, we conduct such identification by inverse analysis coupling simulation and experiments.…”

“…Roux-Langlois et al (2015) analysed the displacement field with DIC on a sub-volume of the sample, to first, project the measured displacements on a William's basis to evaluate the Stress intensity Factors of a fatigue crack, and second, to provide boundary conditions for an XFEM simulation on a sub-volume surrounding the crack. Finally, Nguyen et al (2016a) performed direct quantitative predictions of crack propagation in drilled plaster specimen under compression with phase field numerical simulations which favourably compared with experimental investigations obtained in Romani et al (2015).…”

A phase field method for modeling stress corrosion crack propagation in a nickel base alloy

“…In the second case, l should be identified from experimental data. Such analysis with experimental validations has been recently published in Nguyen et al (2016). It is demonstrated that this kind of regularized model converge to the brittle failure theory when l vanishes.…”