Experimental Measurement of the Energy Dissipative Mechanisms of the Kevlar Micro-fibrillar Network for Multi-scale Application

The study presented in this paper is a subset of the research described in a manuscript by the authors that was accepted for publication. In this study, nanoindentation tests were conducted on the surfaces of Kevlar 49 single fibers under a variety of contact conditions (i.e., probe geometry, indentation depth, and effective strain). The total, absorbed, and recovered energies of indentation were measured and associated with the observed deformation mechanisms of the Kevlar fibrillar network. To directly compare the energies of indentations made with the different probe geometries, the total energy of indentation was normalized by probe volume (i.e., specific energy). In general, the total energy, the percentage of the total energy that was absorbed, and specific energy of indentation increased as indentation depth and/or the effective strain increased, which correlated with the onset of additional fibril deformation mechanisms.