Hrapko M, van Dommelen J A W, Peters G W M, Wismans J S H M
Materials Technology Institute, Eindhoven University of Technology, Eindhoven, The Netherlands.
Biorheology. 2006;43(5):623-36.
The non-linear mechanical behaviour of porcine brain tissue in large shear deformations is determined. An improved method for rotational shear experiments is used, producing an approximately homogeneous strain field and leading to an enhanced accuracy. Results from oscillatory shear experiments with a strain amplitude of 0.01 and frequencies ranging from 0.04 to 16 Hz are given. The immediate loss of structural integrity, due to large deformations, influencing the mechanical behaviour of brain tissue, at the time scale of loading, is investigated. No significant immediate mechanical damage is observed for these shear deformations up to strains of 0.45. Moreover, the material behaviour during complex loading histories (loading-unloading) is investigated. Stress relaxation experiments for strains up to 0.2 and constant strain rate experiments for shear rates from 0.01 to 1 s(-1) and strains up to 0.15 are presented. A new differential viscoelastic model is used to describe the mechanical response of brain tissue. The model is formulated in terms of a large strain viscoelastic framework and considers non-linear viscous deformations in combination with non-linear elastic behaviour. This constitutive model is readily applicable in three-dimensional head models in order to predict the mechanical response of the intra-cranial contents due to an impact.
确定了猪脑组织在大剪切变形下的非线性力学行为。采用了一种改进的旋转剪切实验方法，产生了近似均匀的应变场并提高了精度。给出了应变幅值为0.01且频率范围为0.04至16Hz的振荡剪切实验结果。研究了在加载时间尺度上，由于大变形导致的结构完整性的立即丧失对脑组织力学行为的影响。对于高达0.45应变的这些剪切变形，未观察到明显的即时机械损伤。此外，还研究了复杂加载历史（加载-卸载）过程中的材料行为。给出了应变高达0.2的应力松弛实验以及剪切速率从0.01至1s⁻¹且应变高达0.15的等应变率实验。使用一种新的微分粘弹性模型来描述脑组织的力学响应。该模型基于大应变粘弹性框架制定，并考虑了非线性粘性变形与非线性弹性行为的组合。这种本构模型很容易应用于三维头部模型，以预测由于撞击导致的颅内内容物的力学响应。
