Wu John Z, Dong Ren G, Schopper Aaron W
National Institute for Occupational Safety and Health, 1095 Willowdale Road, Morgantown, WV 26505, USA.
J Biomech. 2004 Jan;37(1):147-55. doi: 10.1016/s0021-9290(03)00240-9.
Frictionless specimen/platen contact in unconfined compression tests has traditionally been assumed in determining material properties of soft tissues via an analytical solution. In the present study, the suitability of this assumption was examined using a finite element method. The effect of the specimen/platen friction on the mechanical characteristics of soft tissues in unconfined compression was analyzed based on the published experimental data of three different materials (pigskin, pig brain, and human calcaneal fat). The soft tissues were considered to be nonlinear and viscoelastic; the friction coefficient at the contact interface between the specimens and platens was assumed to vary from 0.0 to 0.5. Our numerical simulations show that the tissue specimens are, due to the specimen/platen friction, not compressed in a uniform stress/strain state, as has been traditionally assumed in analytical analysis. The stress of the specimens obtained with the specimen/platen friction can be greater than those with the frictionless specimen/platen contact by more than 50%, even in well-controlled test conditions.
在通过解析解确定软组织材料特性的无侧限压缩试验中，传统上假定试样/压板之间无摩擦接触。在本研究中，使用有限元方法检验了这一假设的适用性。基于三种不同材料（猪皮、猪脑和人跟骨脂肪）已发表的实验数据，分析了试样/压板摩擦对无侧限压缩中软组织力学特性的影响。软组织被视为非线性和粘弹性材料；假定试样与压板之间接触界面的摩擦系数在0.0至0.5之间变化。我们的数值模拟表明，由于试样/压板摩擦，组织试样并非如解析分析中传统假定的那样在均匀应力/应变状态下被压缩。即使在控制良好的试验条件下，考虑试样/压板摩擦时获得的试样应力也可能比无摩擦试样/压板接触时的应力大50%以上。
