Laboratory of Biomedical Physics, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp, Belgium.
J Biomech. 2012 Apr 5;45(6):919-24. doi: 10.1016/j.jbiomech.2012.01.023. Epub 2012 Feb 10.
The tympanic membrane transfers sound waves in the ear canal to mechanical vibrations in the middle ear and cochlea. Good estimates of the mechanical properties of the tympanic membrane are important to obtain realistic models. Up till now, only limited resources about tympanic membrane viscoelastic properties are available in the literature. This study aimed to quantify the viscoelastic properties of gerbil tympanic membrane. Step indentations were applied with a custom indenter on four fresh, intact tympanic membranes and the resulting force relaxation was measured. The reduced relaxation functions were then fitted with two viscoelastic model representations: a 5-parameter Maxwell model and a model with a continuous relaxation spectrum. The average relaxation function is described by an initial rapid decrease of 6.5% with characteristic time 0.77 s, followed by a long term decrease with characteristic time 46 s that gradually tends stable till a total relaxation of 15%. The relaxation curves in the time domain were transformed to complex moduli in the frequency domain. It was found that these transformations yield information on strain-rate dependence only from quasi-static to the very lowest acoustic frequencies. Finally, relaxation and hysteresis were simulated in a finite element model with viscoelastic material properties.
鼓膜将耳道中的声波传递到中耳和耳蜗中的机械振动。对鼓膜的机械性能进行准确估计对于获得现实的模型非常重要。到目前为止，文献中只有关于鼓膜粘弹性特性的有限资源。本研究旨在量化沙鼠鼓膜的粘弹性特性。使用定制压痕器在四个新鲜完整的鼓膜上施加阶跃压痕，并测量由此产生的力松弛。然后，使用两种粘弹性模型表示对简化松弛函数进行拟合：五参数 Maxwell 模型和具有连续松弛谱的模型。平均松弛函数由初始快速下降 6.5%和特征时间 0.77s 描述，随后是长时间下降，特征时间为 46s，逐渐趋于稳定，直到总松弛为 15%。在时域中的松弛曲线被转换到频域中的复数模量。结果发现，这些转换仅在准静态到非常低的声频率范围内提供关于应变率依赖性的信息。最后，使用粘弹性材料特性在有限元模型中模拟松弛和滞后。
