Design of Tessellation Based Load Transfer Mechanisms in Additively Manufactured Lattice Structures to Obtain Hybrid Responses

The quest for obtaining lattice structures with mutually exclusive properties through morphological innovations has been rapidly increasing. Nowadays, lattice structures are not only meant for achieving lightweight components but also to deliver unique hybrid functionalities. In this context, the concept of tessellation is recently developed to obtain specific paths of stimulus (load, heat, fluid, vibration, etc.) transfer based on the required responses. The mechanical and functional properties of the lattice structures can be governed and manipulated by changing the path of stimulus transfer in it. In this study, the uniaxial load is considered as a stimulus to examine the load transfer mechanism and various properties of non-edge-to-edge tessellations. These tessellations were designed based on the principles of metallic crystal stacking systems. The designed tessellations were fabricated using HP multi-jet powder bed fusion technology. The deformation behavior, load transfer via stress contours, and equivalent plastic strain (PEEQ) were investigated using experimental compression and numerical analysis. The study reveals unique mechanical properties with changes in structural behavior upon changing the load transfer mechanism (i.e. tessellations). The study reveals radial, zig-zag, and S-shaped patterns of load transfers in BCC, FCC, and HCP tessellated lattice structures. As a result, both the BCC and FCC tessellated lattice structures are known for their load-bearing properties. FCC tessellation demonstrates the highest strength and specific energy absorption capacity. The PEEQ analysis shows extreme plastic deformation in many regions which is cross-validated by cracks in the experimental samples. Contrary to that, HCP is the only structure that shows a constant positive plateau slope until densification. The quasi-static crash force efficiency of the HCP structure outperforms its other counterparts. Moreover, the HCP lattice structure also shows very few locations of plastic deformation with a PEEQ value not exceeding 25%. These properties make HCP a suitable choice for generating cushioning effect. The real-time applications of these structures are presented in protective helmets which need high-strength strength outer covering and high cushioning inner liner. Similarly, the advantageous properties can also be exploited in customized athletic shoes.