Mechanical Behavior of Non-bonded Fiber Networks in Compression

The mechanical behavior of an ensemble of fibers which are not bonded to each other subjected to compression is studied using a numerical model. It is shown that the stress-strain curve is a power law and the strain energy is stored predominantly in the bending deformation mode of the fibers. Hysteresis is observed when the system is subjected to cyclic loading-unloading, with a stable hysteresis loop being obtained after few cycles. The deformation is not smooth; rather it is dominated by instabilities which lead to pronounced stress drops. These instabilities are due to relative fiber sliding and rearrangement and a correlation is observed between stress drops and collective sliding events. The resulting jerky flow is observed even in absence of friction between fibers and is a result of the evolution of the system over a rough energy landscape during compression.