Dynamic enhancement mechanism of energy absorption of multi-cell thin-walled tube

Abstract

In order to study dynamic response of multi-cell thin-wall tubes with small aspect ratio and diameter thickness ratio under high velocity impacts of lightweight devices, the mass block impact tests were performed on three types of thin-walled tubes including circular tube (CirT), multi-cell tube (MT) and polyurethane foam (PUR) filled multi-cell tube (FMT). The dynamic enhancement mechanism of collapse force of MTs was discussed based on numerical simulation and deformation pattern analysis of MTs and FMTs. The results indicated that the dynamic enhancement coefficient of mean crushing force (MCF) was 1.0–1.17 and 1.12–1.3 for MTs and FMTs, respectively. The dynamic enhancement of EA was 24–29.2% for CirTs, 0–14.7% for MTs and 9.42–21.16% for FMTs, compared to the quasi-static compression. The multi-cellularization tended to degenerate the sensitivity of collapse force of MTs to the loading rate, while the foam filling increased the rate sensitivity. With the impact velocity increasing from 30 to 70 m/s, the folding half-wavelength of MTs and FMTs decreased about 2–5 mm. Also, the effective stress level of the MTs increased with the impact velocity and the material strain hardening mechanism. The folding pattern of MTs could be improved by foam filling and enhancing the impact velocity.