1987 | Gilles Pijaudier-Cabot, Zdeněk Pavel Bažant
The paper introduces a nonlocal damage theory to address the issues of spurious mesh sensitivity and incorrect convergence in finite element analysis when dealing with strain softening. The key idea is to apply nonlocal treatment only to variables that control strain softening, while treating the elastic part of the strain as local. This approach is based on continuum damage mechanics, which allows for separating the nonlocal treatment of damage from the local treatment of elastic behavior. The nonlocal damage energy release rate is replaced with its spatial average over a representative volume of the material, ensuring proper convergence and avoiding spurious mesh sensitivity. Numerical examples, including static strain softening in a bar, longitudinal wave propagation in strain-softening materials, and static layered finite element analysis of a beam, demonstrate the effectiveness of the nonlocal damage theory. The theory also shows that averaging the fracturing strain leads to an equivalent formulation that can be extended to anisotropic damage due to highly oriented cracking.The paper introduces a nonlocal damage theory to address the issues of spurious mesh sensitivity and incorrect convergence in finite element analysis when dealing with strain softening. The key idea is to apply nonlocal treatment only to variables that control strain softening, while treating the elastic part of the strain as local. This approach is based on continuum damage mechanics, which allows for separating the nonlocal treatment of damage from the local treatment of elastic behavior. The nonlocal damage energy release rate is replaced with its spatial average over a representative volume of the material, ensuring proper convergence and avoiding spurious mesh sensitivity. Numerical examples, including static strain softening in a bar, longitudinal wave propagation in strain-softening materials, and static layered finite element analysis of a beam, demonstrate the effectiveness of the nonlocal damage theory. The theory also shows that averaging the fracturing strain leads to an equivalent formulation that can be extended to anisotropic damage due to highly oriented cracking.