Abstract
AbstractA modified non‐local damage model with evolving internal length, inspired from micromechanics, is developed. It is shown in particular that the non‐local influence between two points in the damaged material depends on the value of damage at each of these points. The resulting weight function is non‐symmetric and truncated. Finite element results and strain localization analysis on a one‐dimensional problem are presented and compared to those of the original non‐local damage model. It is shown that in the course of damage localization, the incremental strain profiles expand according to the modified non‐local model, instead of shrinking according to the original constitutive relation. Comparisons with experimental data on model materials with controlled porosity are also discussed. Acoustic emission analyses provide results with which the theoretical model is consistent qualitatively. This model also opens the path for durability mechanics analyses, where it has been demonstrated that the internal length in the non‐local model should evolve with environmentally induced damage. Copyright © 2004 John Wiley & Sons, Ltd.
Highlights
Non-local continuum damage, in an integral or gradient format, is a consistent general concept for macroscopic modelling of failure in quasi-brittle materials
The non-local aspect is a requisite for a realistic description of fracture, including crack inception, crack propagation and structural size effect which is a consequence of the existence of a finite size fracture process zone (FPZ)
Several works have focused on relating acoustic emission characteristics to the properties of the fracture process zone [11] and using Acoustic emission (AE) source location analysis to evaluate damage localization [12, 13]
Summary
Non-local continuum damage, in an integral or gradient format, is a consistent general concept for macroscopic modelling of failure in quasi-brittle materials. Among the governing parameters in the non-local damage model, the internal length plays a pivotal role as it controls the size of the fracture process zone. There are some theoretical indications, which suggest that the internal length should change in the course of the fracture process. With the help of micromechanics, Bazant [1, 2] has proposed a description of the interactions between cracks and voids in the course of failure. Geers has observed that, in a gradient damage model, the internal length should change so that the continuum-based constitutive relations can describe fracture with a displacement discontinuity across the crack faces when damage is equal to one [4]. In the course of the degradation process, the internal length should evolve
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