Evaluating the nonlinear dynamics of human descending thoracic aortas is essential for building the next generation of vascular prostheses. This study characterizes the nonlinear dynamics, viscoelastic material properties and fluid-structure interaction of eleven ex-vivo} human descending thoracic aortas in the full range of physiological heart rates. The aortic segments were harvested from heart beating donors screened for transplants. A mock circulatory loop was developed to reproduce physiological pulsatile pressure and flow. The results showed cyclic axisymmetric diameter changes, which were satisfactorily compared to in-vivo} measurements at a resting pulse rate of 60 bpm, with an additional bending vibration. An increase of the dynamic stiffness (i.e. storage modulus) with age was also observed. This was accompanied by a strong reduction with age of the cyclic diameter change during the heart pulsation at 60 bpm and by a significant reduction of the loss factor (i.e. damping). Large dissipation was observed at higher pulse rates due to the combined effects of fluid-structure interaction and viscoelasticity of the aortic wall. This study presents data necessary for developing innovative grafts that better mimic the dynamics of the aorta.

中文翻译：

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人类主动脉的非线性动力学用于材料表征

评估人类胸主动脉下降的非线性动力学对于构建下一代人工血管至关重要。这项研究的特点是在整个生理心率范围内十一个人离体胸廓主动脉的非线性动力学，粘弹性材料特性和流固耦合。从筛选出移植物的心脏跳动供体中收获主动脉段。模拟循环回路被开发来再现生理脉动压力和流量。结果显示了周期性的轴对称直径变化，与静息脉冲速率为60 bpm的活体内测量结果相比，具有令人满意的比较，并带有附加的弯曲振动。还观察到动态刚度（即储能模量）随着年龄的增长而增加。这伴随着心脏搏动在60 bpm时循环直径变化的年龄大大降低，并且损耗因子（即阻尼）显着降低。由于流体-结构相互作用和主动脉壁粘弹性的综合作用，在较高的脉冲频率下观察到较大的耗散。这项研究提供了开发创新的移植物以更好地模拟主动脉动力学所必需的数据。