Subramanian Gopinath, Picu Catalin R
Scientific Computation Research Center, Rensselaer Polytechnic Institute, Troy, New York 12180-3590, USA.
Phys Rev E Stat Nonlin Soft Matter Phys. 2011 May;83(5 Pt 2):056120. doi: 10.1103/PhysRevE.83.056120. Epub 2011 May 25.
The mechanical behavior of an ensemble of athermal fibers forming a nonbonded network subjected to triaxial compression is studied using a numerical model. The response exhibits a power law dependence of stress on the dilatation strain and hysteresis upon loading and unloading. A stable hysteresis loop results after the first loading and unloading cycle. In the early stages of compaction, strain energy is associated primarily with the bending of fibers, while at higher densities, it is stored primarily in the axial deformation mode. It is shown that the exponent of the power law, and the partition of energy in the axial and bending modes depends on the ratio of the bending to axial stiffness of the fibers. Accounting for interfiber friction does not change the functional form of the stress-strain relationship or the exponent. The central feature that distinguishes the mechanics of this system from that of bonded random networks is the relative sliding at contacts and the ensuing fiber rearrangements. We show that suppressing sliding leads to a much stiffer response. The results indicate that the value of the exponent of the stress-strain power law is determined not only by fiber bending and the formation of new contacts, but also by the relative sliding and axial deformation of fibers.
使用数值模型研究了形成非键合网络的无热纤维集合体在三轴压缩下的力学行为。该响应表现出应力对应变膨胀的幂律依赖性以及加载和卸载时的滞后现象。在第一次加载和卸载循环后会形成一个稳定的滞后回线。在压实的早期阶段，应变能主要与纤维的弯曲相关，而在更高密度下，它主要存储在轴向变形模式中。结果表明，幂律的指数以及轴向和弯曲模式中的能量分配取决于纤维弯曲刚度与轴向刚度的比值。考虑纤维间摩擦并不会改变应力 - 应变关系的函数形式或指数。该系统力学与键合随机网络力学的核心区别特征在于接触处的相对滑动以及随之而来的纤维重排。我们表明，抑制滑动会导致响应刚度大幅增加。结果表明，应力 - 应变幂律指数的值不仅由纤维弯曲和新接触的形成决定，还由纤维的相对滑动和轴向变形决定。
