Abstract
Lattices are periodic three-dimensional architected solids designed at the micro and nanoscale to achieve unique properties not attainable by their constituent materials. The design of lightweight and strong structured solids by additive manufacturing requires the use of high-strength constituent materials and non-slender geometries to prevent strut elastic instabilities. Low slenderness carbon octet microlattices are obtained through pyrolysis of polymeric architectures manufactured with stereolithography technique. Their compressive behaviour is numerically and experimentally investigated when the relative density $\bar{\rho}$ ranges between 10$\%$ and 50$\%$, \textcolor{red}{with specific stiffness and strength approaching the limit of existing micro and nanoarchitectures}. It is shown that additive manufacturing can introduce imperfections such as increased nodal volume, non-cubic unit cell, and orientation-dependent beam slenderness, all of which deeply affect the mechanical response of the lattice material. An accurate numerical modelling of non-slender octet lattices with significant nodal volumes is demonstrated to overcome the limitations of classical analytical methods based on beam theory for the prediction of the lattice stiffness, strength and scaling laws. The presented numerical results and experimental methods provide new insights for the design of structural carbon architected materials towards ultra-strong and lightweight solids.
Highlights
Additive manufacturing has become one of the most promising technique to fabricate advanced materials and microstructures that exhibit properties unattained by homogeneous solids or conventionally manufactured architectures
We show that digital light processing stereolithography (DLP-SLA) 3D printing and pyrolysis techniques can affect the designed lattice architecture introducing undesired features as increased nodal volume, non-cubic unit cell and different strut slenderness depending on the beam orientation with respect to the printing direction
We have investigated the compressive behavior of stiff and strong non-slender octet carbon microlattices obtained by pyrolyzing 3D-printed polymer architectures fabricated through stereolithography
Summary
Additive manufacturing has become one of the most promising technique to fabricate advanced materials and microstructures that exhibit properties unattained by homogeneous solids or conventionally manufactured architectures. The field of architected material has benefited from the advancement of small-scale manufacturing that enables the design of multistable solids for energy storage (Shan et al, 2015), the evolution of phononic bandgap behavior (Sugino et al, 2015; Amendola et al, 2018) and the exploration of previously inaccessible mechanical property combinations (Bauer et al, 2016). Examples include structural metamaterials designed to achieve extremely lightweight and strong solids through a hierarchical design (Meza et al, 2015) or novel highly deformable and recoverable nanolattices made up of brittle materials (Meza et al, 2014)
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