Department of Applied Mechanics and Engineering, Southwest Jiaotong University, Chengdu, Sichuan 610031, China.
J Mech Behav Biomed Mater. 2011 Apr;4(3):498-506. doi: 10.1016/j.jmbbm.2010.12.015. Epub 2010 Dec 29.
Skin soft tissue (e.g., porcine skin) was tested in vitro under uniaxial cyclic loading, and its biomechanical responses were investigated to realize some basic properties which are very significant in assessing the fatigue life of skin soft tissue. The results show that a cyclic accumulation of peak and valley strain, which can be terminologically called as ratchetting in terms of material science of metals, occurs in the porcine skin during cyclic tension-unloading, tension-tension and compression-unloading tests. Observed ratchetting of porcine skin depends on load level and loading orientation greatly and also presents remarkable rate dependence due to the viscosity of skin soft tissue. The ratchetting is much more remarkable during the test at lower loading rate than that at higher loading rate. Moreover, some basic properties of porcine skin were also investigated by monotonic tension, compression and creep tests in order to address the ratchetting more comprehensively. Finally, collagen fiber bundles in the porcine skin and their variation during monotonic and cyclic tension tests were observed microscopically in term of standard iron-hematoxylin staining method. The observations are useful to realize the micro-mechanism of ratchetting deformation.
皮肤软组织（如猪皮）在体外进行单轴循环加载测试，研究其生物力学响应，以实现一些在评估皮肤软组织疲劳寿命方面非常重要的基本特性。结果表明，在猪皮的循环拉伸-卸载、拉伸-拉伸和压缩-卸载测试中，会出现峰谷应变的循环累积，这在金属材料科学中可以称为棘轮效应。观察到的猪皮棘轮效应很大程度上取决于载荷水平和加载方向，并且由于皮肤软组织的粘性，还呈现出明显的速率依赖性。在较低加载速率下的测试中，棘轮效应比在较高加载速率下更为显著。此外，还通过单调拉伸、压缩和蠕变试验研究了猪皮的一些基本特性，以便更全面地研究棘轮效应。最后，通过标准的铁-苏木精染色法观察了猪皮中的胶原纤维束及其在单调和循环拉伸试验中的变化。这些观察结果有助于实现棘轮变形的微观机制。
