Concept development for innovative functionally graded lattice structures to absorb desired energy and impact

Abstract

Densification and plateau behavior of lattices can be manipulated by selectively grading the cells. Metallic lattices are the conventional choice for energy absorption, while the generated impact has not been the subject of interest. However, this is the crucial requirement for protective applications like mine-blast absorber for armor vehicles. Different gradient approaches have been examined in this study to find the method which not only controls the absorbed energy, but also keeps the impact level below the identified threshold. This includes available density gradients as well as an innovative gradient geometry for the structure. The concept of how each gradient approach influences the plateau behavior was discussed. A novel approach has been presented which enables tracking the impact magnitude during densification. Although, series density-gradient is a common approach to improve energy absorption in industry, the result of this study demonstrates that crushing the denser region of lattice may generate significantly larger impact. Instead, arranging density gradient cells parallelly can absorb higher energy, while the increase in impact is not significant. An innovative design is presented for lattice structure with gradient geometry. It starts absorbing energy at very low impact and ends with significantly higher absorbed energy at full compaction. To expand the domain of application and effectiveness, new gradient approach was proposed by combining geometry and density grading. It was demonstrated that this highly efficient and flexible design configuration could reduce the activation impact by 94% with descending arrangement and double the absorbed energy by ascending arrangement. This was achieved while the impact magnitude was kept at a reasonable level. In addition, design parameters can be adjusted for desired level of energy and impact for particular application.