Composite Strengthening via Stress-Concentration Regions Softening: The Proof of Concept with Schwarzites and Schwarzynes Inspired Multi-Material Additive Manufacturing

Inspired by nature, porous graded topological structures based on carbon, like Schwarzites and Schwartzynes, exhibit a distinctive radial-gradient distribution of pores. The pores are strategically arranged in two patterns: small pores at the centre and larger pores in the outer region (ψ), and larger pores at the centre with smaller pores in the outer region (Ω). This type of topological engineering, with its unique deformation behaviour, makes these structures highly suitable for engineering applications requiring high energy absorption. However, the existence of stress-concentration regions within the porous graded structures leads to premature structural failure during uni-axial compression. To enhance the mechanical properties of such porous graded structures, this study proposes a strategy of tailoring their pores’ deformation characteristics by replacing the stress concentration regions with soft/flexible materials. The selective reinforcing two ( ψ2) and three layers (Ω3) soft material enhances the specific yield strength of the multi-material composite by 187.27 % and 230.22 %, respectively compared to the respective porous soft structures. Specific resilience is heightened by 289.93 % and 323.82 % for multi-material composite ψ2 and Ω3, w.r.t the respective porous hard structure(ψʹ0 and Ω, 0). Our results present a unique strategy for improving the structural performance of the porous graded structures by tailoring the deformation characteristics. Engineered multi-material-based advanced composites, resulting from this approach, exhibit significant potential for applications requiring energy absorption without failure.