Working Mechanism of Nanoporous Energy Absorption System under High Speed Loading

+. The working mechanism of nanoporous energy absorption system (NEAS) under high speed impact loading conditions are explored using molecular dynamics simulations, and the effects of loading rate and tube size are also considered. The present NEAS is composed of a single-walled carbon nanotube (CNT) segment and water molecules. The work done by the impact load can be converted into three parts: (I) water molecules potential change due to nanoconfinement, (11) solid-liquid interaction energy, and (III) the heat dissipated by the solid liquid surface friction. We found that with a small tube size, part III provides the main contribution to the overall energy absorption; with the increase of tube size, part III rapidly decreases, and part I begins to give the main contribution. This result is different with the reported mechanism in which part II is the main contributor. The energy absorption density of NEAS is much higher than that of the conventional energy absorption materials, which decreases with the tube size and slightly increases with the impact loading rate. In addition, water molecules can transport through CNTs very fast under the high loading rate, thus NEAS can meet the requirement of a very low response time to prevent against the high speed impact load. On the basis of our simulations, NEAS can be a very promising candidate to protect against high speed loading.