Study of a compact energy absorber

Abstract

<p>Deformable energy absorbers play a vital role in crash protection systems. However, prevailing stringent design requirements to mitigate impact damage in a limited space have advocated a need for superior energy absorbing materials and versatile and compact structures. In this thesis, an intelligent compact energy absorbing structure is presented that alleviates the impact by distributing load over finite displacement (stroke). The structure's geometry is observed in the cross-section of a banana peel that has a specific graded cellular packing in a confined space. This packing enables the thin peel to protect the internal soft core from external impact loads. The cellular pattern observed in a banana peel is used to construct a finite element analysis model of the structure. The energy absorbing characteristics of the structure are evaluated and compared to the energy absorbing characteristics of a solid section by means of finite element simulations using ABAQUS. The structure was found to reduce the static and dynamic reactive forces up to 83 percent in comparison to a solid section provided the thickness and contact area are kept constant. The energy absorbing characteristics of peel structure were also compared to regular hexagonally shaped cellular honeycombs. The peel structure resulted in lower impacts and severity of deceleration-acceleration phase over regular honeycombs for higher velocity range under the same space/stroke constraints. Analytical models for low and high impact velocities were also developed to calculate the crushing strength and stroke of the graded structure.</p>