<br>多尺度断裂模型揭示仿生 Bouligand 结构的增韧机制,Acta Biomaterialia

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多尺度断裂模型揭示仿生 Bouligand 结构的增韧机制
Acta Biomaterialia ( IF 9.4 ) Pub Date : 2024-01-29 , DOI: 10.1016/j.actbio.2024.01.038
Yunqing Nie ₁ , Dongxu Li ₁

Affiliation

Bouligand 结构已在多种生物材料中观察到，例如层状骨和龙虾的外骨骼。它是一种分层、非同质的架构，表现出优异的抗损坏性能。本文提出了考虑材料不均匀性、多尺度特性和各向异性的多尺度断裂模型，以揭示 Bouligand 结构的增韧机制。首先推导了该复合材料的宏观和微观本构特性。然后，开发了多尺度断裂模型来表征扭曲裂纹裂纹前端的局部应力强度因子和能量释放率。我们的结果表明，局部能量释放率的降低可归因于两步机制。第一个机制是多尺度结构和材料不均匀性导致初始裂纹尖端附近的应力释放。第二个机制是扭曲裂纹导致从单一模式加载转变为混合模式加载，从而增强了断裂韧性。这些结果不仅可以揭示Bouligand结构的增韧机理，而且可以为高性能复合材料的设计提供指导。自然界中的生物材料通常具有合成材料无法达到的优异机械性能。仿生 Bouligand 结构为设计高性能材料提供了原型。在本研究中，我们提出了一种多尺度理论断裂模型来研究具有扭曲裂纹的 Bouligand 结构的断裂特性。我们系统地考虑材料不均匀性、各向异性和多尺度特性的作用。我们的分析表明，Bouligand 结构的卓越韧性是材料不均匀性和扭曲裂纹的综合影响的结果。这项研究有助于揭开 Bouligand 结构卓越韧性背后的秘密，并为人造复合材料新颖设计的开发提供灵感。

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A multiscale fracture model to reveal the toughening mechanism in bioinspired Bouligand structures

The Bouligand structure has been observed in a variety of biological materials, such as lamellar bone and exoskeleton of lobsters. It is a hierarchical and non-homogeneous architecture that exhibits excellent damage-resistant performance. This paper presents a multiscale fracture model considering the material inhomogeneity, the multiscale property, and the anisotropy to reveal the toughening mechanisms in the Bouligand structure. Firstly, the macro and micro constitutive properties of this composite are derived. Then, a multiscale fracture model is developed to characterize the local stress intensity factors and the energy release rates at the crack front of twisted cracks. Our results demonstrate that the decrease in the local energy release rate can be attributed to two-step mechanisms. The first mechanism is that the multiscale structure and the material inhomogeneity cause a release of stress near the initial crack tip. The second mechanism is that the twisted crack leads to the transformation from single-mode loading to mixed-mode loading, which enhances the fracture toughness. These results can not only reveal the toughening mechanism of the Bouligand structure but also provide guidelines for the design of high-performance composites. Biological materials in nature often possess excellent mechanical properties that have not been achieved by synthetic materials. Bioinspired Bouligand structures provide prototypes for designing high-performance materials. In this study, we propose a multiscale theoretical fracture model to investigate the fracture properties of Bouligand structures with twisted cracks. We systematically consider the roles of material inhomogeneity, anisotropy, and multiscale properties. Our analysis demonstrates that the remarkable toughness of Bouligand structures results from the combined effects of material inhomogeneity and twisted cracks. This research contributes to unveiling the secret behind the outstanding toughness of Bouligand structures and provides inspiration for the development of novel designs for man-made composites.

更新日期：2024-01-29

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