The fracture behavior of a cortical bone is significantly affected by its hierarchal structure and a high degree of material anisotropy. Recently, continuum damage models have proven to be an effective tool to characterize such kind of material behavior. However, these models suffer from drawbacks such as mesh dependency, spurious damage growth, and incorrect prediction of damage initiation during the initial stage of loading process. To this end, the objective of this work is to develop a nonlocal gradient-enhanced damage model in an isogeometric setting to predict the fracture behavior of a cortical bone. The numerical framework is formulated considering an additional diffusion equation in conjunction with the standard equilibrium equation. The material is assumed to be transversely isotropic to incorporate the anisotropy in damage evolution. The versatility of the proposed framework is tested by solving problems for different modes of fracture. For numerical simulations, samples are taken from different quadrants of bovine cortical bone, and the effect of anisotropy on the damage characteristics of the bone are investigated.

皮质骨的断裂行为受其分层结构和高度材料各向异性的显着影响。最近，连续介质损伤模型已被证明是表征此类材料行为的有效工具。然而，这些模型存在诸如网格依赖性、虚假损伤增长以及加载过程初始阶段损伤起始预测不正确等缺点。为此，这项工作的目标是在等几何设置中开发非局部梯度增强损伤模型，以预测皮质骨的骨折行为。结合标准平衡方程，考虑额外的扩散方程来制定数值框架。假设材料是横向各向同性的，以在损伤演化中包含各向异性。通过解决不同断裂模式的问题来测试所提出框架的多功能性。对于数值模拟，从牛皮质骨的不同象限中取样，研究各向异性对骨损伤特性的影响。