On mixed-mode fracture of brittle orthotropic solids: A novel micromechanical damage model

• Published in: Engineering fracture mechanics 2025-01, Vol.313, p.110628, Article 110628
• Main Authors: Ebrahimi, Mahdieh Tajabadi, Khaji, Zahra, Fakoor, Mahdi
• Format: Article
• Language: English
• Subjects: Damage zone; Effective stiffness; Fracture criteria; Microcracking
• ISSN: 0013-7944
• DOI: 10.1016/j.engfracmech.2024.110628

This study presents a novel micromechanical fracture criterion based on the strain energy release rate approach for orthotropic materials subjected to mixed-mode loading. By modelling microcrack behaviour and their precise interactions within the material, we developed a more accurate approach to predicting fracture. This criterion takes into account the mechanisms that are responsible for energy loss within the damaged zone. Here, a reinforcement isotropic solid model is employed to model orthotropic materials. This approach places the crack within an isotropic matrix to mitigate stress induced by the fibres. The criterion, validated through modelling and experimental data, demonstrates its effectiveness in capturing the complex interplay between microcrack orientation, quantity, and material properties. Notably, the study reveals that microcracks oriented at a 45-degree angle offer prominent resistance to fracture. While an increase in microcracks generally delays fracture, exceptions arise for specific orientations. Moreover, For the first time, we address the dissimilar behaviour of various orthotopic materials, including Western Whitewood. •Microcracks and their interactions in fracture damage zones of orthotropic materials are studied.•Orthotropic materials are investigated based on the reinforcement isotropic solid framework.•Effective properties reduction due to various numbers of microcracks and orientations is derived.•Toughness mechanism due to damage zone microcracking is examined numerically and experimentally.•A predictive new maximum strain energy release rate fracture criterion is introduced and verified.•The modelled FLCs show sufficient accuracy in comparison with experimental results.