Co-authors​ :

 Mohit SOOD (TAIWAN), Chang-Mou WU (TAIWAN), Jieng-Chiang CHEN (TAIWAN), Ming-Yuan SHEN  

Lattice structures having surface-based or strut-based could be used for the for-energy absorption under compression loading. For the improvement in the energy absorption and mechanical properties under compression, these two types of topologies combined by mimicking the seed growing principle. In the current study, carbon organic framework inspired lattice metamaterials (CFLM) of S2, a strut, and SS having surface-based structure are being used that taken from the previous study. During the seed growth, as the seed starts growing, the soil near it becomes more robust, and when the seed is fully grown, it grips the surrounding soil more firmly. Based upon this inspiration, the surface-based SS structure is considered soil, and the strut-based S2 CFLM is seeded inside the SS structures. To compare the effect of lattice seeding, four different kinds of hybrid lattice were designed and designated as H1, H2, H3, and H4. H1 has the least volume of seed in the form of an S2 lattice, and it is grown in H2 and H3, and in H4 the S2 fully engulfed SS structure. These structures are manufactured by Fused filament fabrication (FFF) from a bio-degradable polylactic acid (PLA) polymer. In the fabricated samples, an excellent inter-layer adhesion of the extruded layer is confirmed by scanning electron microscopy (SEM). All structures have approximately 37% relative volume fraction. All structures are compressed under the constant displacement rate of 5 mm/min in the printing direction. From the results, it is found that H1 densified at the slightest densification strain of 45.83%, and H4 provided the highest densification of 57.27 %. In terms of energy absorption, all seeded structures have almost equal energy absorption capacity and H4 topped with 3.78 MJ/m3. In the case of the peak strength, H2 is the best, with a value of 7.71 MPa. For the case of the modulus, the H1 and H2 showed almost similar values with 255 MPa. The highest mechanical properties of all the seeded structures are compared with the typical SS structure having no seed. It was found that the seeding improved the densification strain of surface-bounded SS structures by 24%. In the case of energy absorption and peak yield strength, 40% and 34% improvement are observed, respectively. On comparison of the stiffness an increment of 32% is observed than the structure without seeding. Deformation images show that as the amount of the seed increases, the severity of delamination decreases but is not eliminated. In conclusion, the seeding of the strut inside the surface-bounded lattice successfully enhanced the mechanical properties and energy absorption capacity of the surface-based lattice structures.