Comparative analysis of mechanical properties and energy absorption capabilities of functionally graded and non-graded thermoplastic sheet gyroid structures

Abstract

Additive manufacturing allows the tailoring of the structure of energy-absorbing materials. It is thus feasible now to use light, printed structures instead of other materials such as foams and honeycombs, signifying greater possibilities for customization. Some of these structures are triply periodic minimal-surface structures that is a family of different structures like the gyroid one. Another benefit of additively manufactured graded structures, which foams or honeycombs lack, is the flexibility to vary the internal parameters along one or more directions. This study focuses on the comparative analysis of graded and non-graded gyroid structures for four common thermoplastic materials used in additive manufacturing. These structures are compared with each other under quasi-static compression testing, as well as with expanded polystyrene foam and solid samples of the thermoplastic materials. The analysis includes investigation of the stress–strain and specific stress–strain curves, capability of absorbing energy per unit weight and per unit volume, ideality, total efficiency, and normalized energy vs. normalized stress characteristics. We also analyze the internal fracture mechanism of the structures. The objective is to obtain more extensive knowledge of the behavior of non-graded structures.

Keywords:

• Periodic cellular lattice structures
• triply periodic minimal surfaces (TPMS)
• additive manufacturing
• compression
• energy absorption
• thermoplastic

Acknowledgements

The authors would like to thank nTopology that provided the software that was essential to prepare all the CAD models.

Additional information

Funding

This work was supported by the “University of ZaragozaCentro Universitario de la Defensa” joint Research Grant (grant number UZCUD2019-TEC-04).