This study aims constitutive modeling of rate dependent anisotropic viscoelastic brain tissue that experiences large deformation during accidental impact. Many experimental studies confirm that brain parenchyma mechanisms are strongly influenced by anisotropy, nonlinear viscoelasticity, rate dependent loading/unloading and tension-compression asymmetry of the soft brain tissues. We present a rigorous thermodynamically consistent phenomenological approach to capture these mechanisms in a single model. Model parameters are calibrated from the experiments, and mechanical responses are predicted for different loading conditions. We consider a 2-D fibrous circular tube geometry, an idealized form of a human head, to simulate shear stress distribution for a given boundary condition. Different orientations of the fibers are considered to investigate the influence of anisotropy on the shear stress. Finally, stretch rate dependency of stress responses for a particular fiber orientation is demonstrated.

这项研究旨在本构模型的速率依赖的各向异性粘弹性脑组织，在意外撞击过程中会经历大的变形。许多实验研究证实，脑实质的机制受软组织的各向异性，非线性粘弹性，速率依赖的加载/卸载和张力-压缩不对称性的强烈影响。我们提出了严格的热力学一致现象学方法，以在单个模型中捕获这些机制。从实验中校准模型参数，并预测不同负载条件下的机械响应。我们考虑二维纤维圆管几何形状（人头的理想形式），以模拟给定边界条件下的切应力分布。考虑纤维的不同取向以研究各向异性对剪切应力的影响。最后，证明了应力响应对特定纤维取向的拉伸速率依赖性。