Wang Qi, Hayward Vincent
Haptics Laboratory, Centre for Intelligent Machines, McGill University, 3480 University Street, Montréal, H3A 2A7, Canada.
J Biomech. 2007;40(4):851-60. doi: 10.1016/j.jbiomech.2006.03.004. Epub 2006 May 8.
Small patches of fingerpad glabrous skin in human subjects were tested in vivo for their biomechanical properties under tangential loading and for large deformations. These conditions included stretching and shearing the skin at a length scale of 0.3mm using an apparatus comprising a pair of piezoelectric benders arranged to increase the stiffness/free deflection tradeoff when compared to ordinary cantilevered benders. It was then possible to test the skin with up to 80% of tangential strain. With feedback control, it was also possible to create isotonic and isometric testing conditions. The results showed much variability across subjects and it was seen that the glabrous skin exhibited nonlinear stiffening in tangential traction. The skin was consistently more elastic across the ridges than along the ridges regardless of the location of the sample on the fingerpad. The skin behaved visco-elastically but relaxed about twice as fast than it crept. Finally, it was found that under large deformation, there was consistently 80% of hysteretic loss for a wide range of loading conditions.
在体内对人类受试者手指腹无毛皮肤的小区域进行了测试，以研究其在切向加载和大变形情况下的生物力学特性。这些测试条件包括使用一种装置在0.3毫米的长度尺度上对皮肤进行拉伸和剪切，该装置由一对压电弯曲器组成，与普通悬臂弯曲器相比，其刚度/自由挠度权衡有所增加。这样就能够对皮肤进行高达80%的切向应变测试。通过反馈控制，还能够创建等张和等长测试条件。结果显示，不同受试者之间存在很大差异，并且发现无毛皮肤在切向牵引中表现出非线性硬化。无论样本在手指腹上的位置如何，皮肤在纹路方向上始终比沿纹路方向更具弹性。皮肤表现出粘弹性，但松弛速度比蠕变速度快约两倍。最后，发现在大变形情况下，在广泛的加载条件下始终存在80%的滞后损失。
