Identification of damage and cracking behaviours based on energy dissipation mode analysis in a quasi-brittle material using digital image correlation

Abstract

Characterizing the crack stability to predict the behaviour of ceramics designed for industrial use is a challenging issue. It requires accurate crack tip detection during the controlled crack propagation of notched bending tests. Different indirect methods are available, like for instance the compliance technique. Recently, techniques based on digital image correlation (DIC) have emerged: finite-element DIC (FE-DIC) with a finite element decomposition of the displacement field, integrated-DIC (I-DIC) based on Williams' series decomposition of the displacement field and regularized-DIC (R-DIC) for mechanical constraints. These full-field techniques enable the quantification of the crack length and the stress intensity factor K I . In this paper, these four methods are compared in terms of measurements of crack lengths and stress intensity factors during a notched bending test. The tested material is a damageable quasi-brittle ceramic at room temperature. The non linearity of the stress-strain law of this microcraked ceramic results in a complex behaviour that is not captured by the compliance method during the bending test. Therefore the linear elastic compliance method leads to a different estimation of crack lengths and stress intensity factors compared to DIC methods. On the other hand, the R-DIC approach handles the non linear material constitutive behaviour. It allows a deeper analysis of the mechanical fields, the energy dissipation and the damage mechanisms during the crack propagation.

Identification of asymmetric constitutive laws at high temperature based on Digital Image Correlation

“…A methodology based on Digital Image Correlation (DIC) has been proposed previously by the authors 8,9 to characterize damageable ceramics which have different mechanical behaviours between tension and compression at room temperature. Compression, tension and four point bending tests have been analysed.…”

Characterization of the Mechanical Behavior of Magnesia Spinel Refractories Using Image Correlation

“…The tensile stress σ are deduced using the relationships established within the framework of linear elastic beam. It assumes a symmetric tensile–compressive behavior and leads to incorrect estimations in case of asymmetric nonlinear behavior …”

Crack path tracking from full field measurements: A novel empirical methodology

“…Yoneyama et al use an iterative procedure based on the Newton‐Raphson method to determine the crack tip location and the mixed‐mode stress intensity factors at the same time. According to Réthoré, a more robust approach consists in relying on the concept of an elastic crack tip which is detected using the first super‐singular term of the William's expansion . This approach requires the delineation of the process zone, which is omitted during the identification of Williams' expansion.…”