作为人体重要的器官的骨组织是一种结构极为复杂的生物复合材料，其损伤力学行为研究本身具有相当大的难度，而骨组织的损伤演化对人体健康也具有重大意义。本项目针对目前骨损伤理论模型简单无法反映骨各向异性多尺度损伤的问题，引入微裂纹扩展区细观损伤力学理论，基于多尺度的实验观察，在骨单元和骨内线裂纹两个尺度分别建立各自的损伤本构和演化方程；利用数字散斑相关方法对骨的两尺度损伤力学行为进行观测，通过实验识别不同尺度的损伤模型参数；选取合适的损伤变量，将两个尺度的损伤本构耦合组成跨尺度的骨损伤力学本构模型；最后基于新建立的损伤力学模型，考虑骨的重建修复作用，模拟一些典型的与骨损伤有关的临床案例，验证模型的有效性和可靠性。本项目从具体的骨材料结构特点出发，结合现代实验技术手段验证与补充的研究方法，可以推动细观损伤力学理论与方法在骨的损伤领域得到更好地应用，使对骨损伤的定量理论描述更加精确。

Bone is the major structural material in our bodies. The damage behavior of bone is very difficult to the researchers due to its complex hierarchical composite of collagen and hydroxyapatite. Currently the study of damage is a very active field; many experimental studies have been undertaken in recent years, showing, for example, that damage can be linked to reduced stiffness, to ageing in humans and animals and to osteoporosis and its treatment. But now we lack a clear theoretical perspective from which to view all this information of bone damage. As a result, the DMG damage theories of brittle materials are introduced to investigate the bone damage behavior in two different scales. Two damage models will be developed for the osteons and the micro-cracks separately. New damage parameters are then involved to describe the anisotropy and complicated damage of bone which relate to the characteristic structural dimensions in bone. The Digital Speckle Correlation Method is utilized to reveal how the complex structure is imbued with mechanisms to resist fracture at different size scales by increasing energy dissipation. And the experimental identification method is used to indentify to what extent the bone is damaged by fatigue. Then a new damage model is established to rationalize the damage evolution law of bone under simultaneously applied complicated loads. Some crucial physical and biological mechanisms underlying the sophisticated damage process of bone tissues have been incorporated in the model. Especially, an evolutionary law of bone damage is presented to analyze the complicated damage/repair behavior of bone. The new proposed model can be used to predict the fracture risk of damaged bone and the results do suggest some clinical uses in the future.