Chapter 9: Iterative Design Studies on Additively Manufactured Energy Absorbing Structures

The ability to protect vital infrastructure and to provide secure transport containers is critical for the future storage, handling, and deployment of energetic materials. Therefore, investigation of energy-absorbing structures which are light-weight and accessible for urban and transport environment is crucial. The recent advances in the additive manufacturing (AM) have allowed the development of light-weight, energy-absorbing structures to be more precise and efficient. Given the range of potential materials applicational flexibility is superior to the existing polymer-based foams. The advantages of rapid prototyping, enabled through AM, allows a streamlined process in obtaining a structure of desired mechanical behaviour. In this work, a development, design variation of a flexible lattice structure with core strut modification is demonstrated. The core struts are varied in terms of shape and density and are fabricated using stereolithography (SLA) and experimental methodology is outlined for the characterisation of the printed specimen under compressive loading. Mechanical characterisation under different strain rates presents that the implementation of the core strut increases the elastic modulus of the lattice structure. The enhanced stiffness effects are further increased with the variations in shape, while the evaluation of the density variations shows significantly different deformation behaviour and strain rate sensitivity. Lastly, the comparison of the structures to other soft materials such as polyurethane, hydrogel and gelatine presents that the different core variants can effectively match the deformation stress levels of these materials, demonstrating the functional efficiency and the viability of additively manufactured structures.