Abstract
Today, the rational combination of materials and design has enabled the development of bio-inspired lattice structures with unprecedented properties to mimic biological features. The present study aims to investigate the mechanical performance and energy absorption capacity of such sophisticated hybrid soft–hard structures with gradient lattices. The structures are designed based on the diversity of materials and graded size of the unit cells. By changing the unit cell size and arrangement, five different graded lattice structures with various relative densities made of soft and hard materials are numerically investigated. The simulations are implemented using ANSYS finite element modeling (FEM) (2020 R1, 2020, ANSYS Inc., Canonsburg, PA, USA) considering elastic-plastic and the hardening behavior of the materials and geometrical non-linearity. The numerical results are validated against experimental data on three-dimensional (3D)-printed lattices revealing the high accuracy of the FEM. Then, by combination of the dissimilar soft and hard polymeric materials in a homogenous hexagonal lattice structure, two dual-material mechanical lattice statures are designed, and their mechanical performance and energy absorption are studied. The results reveal that not only gradual changes in the unit cell size provide more energy absorption and improve mechanical performance, but also the rational combination of soft and hard materials make the lattice structure with the maximum energy absorption and stiffness, in comparison to those structures with a single material, interesting for multi-functional applications.
Highlights
Mechanical meta-materials demonstrate unprecedented mechanical properties that directly originate in their geometrical designs at different scales, in particular, small scales that are engineered to achieve unusual properties at the bulk [1,2,3]
Five different graded size hexagonal lattice structures made from thermoplastic co-polymer (TPC) and PA12 were designed, and their mechanical compressive force-displacement and energy absorption were investigated
The presented numerical simulations were performed using finite element modeling (FEM) implemented in ANSYS by considering elastic/plastic and hardening material behaviors
Summary
Mechanical meta-materials demonstrate unprecedented mechanical properties that directly originate in their geometrical designs at different scales, in particular, small scales that are engineered to achieve unusual properties at the bulk (or macroscale) [1,2,3]. Architected mechanical (multi) meta-materials and bio-inspired cellular structures have been shown as good alternatives with high energy absorption for multi-functional applications [15]. Mechanical performance and energy absorption of two-dimensional (2D) and 3D lattice structures can be tuned by integrating graded size, multiple material (volume fraction of materials, softhard interactions and configurations) through rational design and triply periodic minimal surfaces (TPMS) or topology optimization [20,21,22,23,24,25,26,27]. The mechanical performance (e.g., the quasi-static compression test) and energy absorption capacity of five types of graded cellular structures with soft and hard materials and two types of dual-material lattice structures are investigated. IInn ssaammppllee 33 ((FFiigguurree 11cc)),, tthhee ddiirreeccttiioonn ooff cchhaannggeessiissooppppoossitieteoofftthheessaammpplele. Once it is verified that there are no compression problems, the density of the materials is changed back to normal to ensure the original problem is being simulated with the increased solver time
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