Dynamic compressive behavior of foamed polyethylene film

¹ Graduate Student, School of Systems Engineering, National Defense Academy, Kanagawa 239-8686, Japan
² School of Systems Engineering, National Defense Academy, Kanagawa 239-8686, Japan
³ Foam Development Center, Sekisui Chemical Co., LTD., Saitama 616-8255, Japan
⁴ Institute of Space Dynamics, Kyoto 616-8255, Japan

^a Corresponding author: ymda@nda.ac.jp

Published online: 7 September 2015

Abstract

The foamed film as the shock absorption material has attracted much attention because it is thin (100 μm ∼ 400 μm) and has a closed cell structure. However, the dynamic mechanical properties have not been reported in the foamed film. The purpose of this study is to elucidate the compressive behavior of the foamed polyethylene film at the wide strain rate range. First, the new compressive test apparatus for the dynamic strain rate, the drop-weight testing machine with opposed load cell, was developed, which can be also evaluated the dynamic stress equilibrium of the specimen. It is confirmed that the compressive flow stress increased with increasing the strain rate, regardless of the film thickness. The foamed polyethylene film has the high strain rate sensitivity in the quasi-static deformation. On the other hand, there is almost no change of the strain rate sensitivity in the dynamic and the impact deformation. In order to investigate the mechanism of strain rate dependence, the foamed polyethylene film was observed by X-ray computed tomography scanner before and after compressive test. The fracture of the closed cell only occurred in the quasi-static deformation. It was clarified that the strain rate sensitivity of the foamed film depends strongly on that of the construction material, polyethylene.