类骨纳米结构生物材料的细观力学分析

根据贝壳、 骨骼等生物材料在纳米尺度的微结构特征, 采用剪滞模型, 分别推导了蛋白质材料为线弹性和弹塑性时类骨材料的等效模量和总体应力应变曲线。通过与有限元以及Gao等人的拉剪链模型结果的比较, 分析了线性剪滞模型和拉剪链模型在研究类骨材料等效模量时的有效性。结果显示, 剪滞模型与二维有限元结果符合较好, 拉剪链模型在长细比较大时与有限元结果偏离较大。进一步将弹塑性剪滞模型预测的应力-应变曲线与实验测量结果进行了比较, 两者符合较好。从模拟结果中可以看出, 在刚度发生明显降低之前, 已经有部分蛋白质进入塑性变形, 从而反映了生物材料的能耗与增韧特征。 

Micromechanical analysis for bone-like nanostructural biomaterials

Shear lag analysis was applied to bone-like nanostructural biomaterials such as nacre and bone with unique structure in nano scale. The models for protein with both linear and elastic-plastic deformations were developed. Compared with the results of finite element method (FEM) and the tension shear chain model of Gao, the linear shear lag model fits better with FEM while the tension shear chain model predicts a larger effective modulus when the aspect ratio is large. The elastic-plastic shear lag model fits well with the experimental results, and the plastic deformation takes place before the modulus of the materials decreases obviously, which provides those materials the ability to dissipate energy and enhance the toughness.