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• Lattice structures with eccentric body center were proposed for energy absorption. • Statistical pattern recognition was used to classify the EBCC lattice structures. • An RBF surrogate model was established for energy absorption optimization. • Symmetric surrogate model with improved efficiency was proposed. Lattice structures have shown excellent mechanical properties, such as high energy absorption capacity. In this work, the extended body centered cubic lattice was proposed by offsetting the position of the body center. The pattern recognition method of nonlinear discriminant function was creatively used to classify the proposed eccentric body centered cubic (EBCC) lattice structures according to their deformation patterns. The results indicated that the lattice structures belong to X-Pattern possessed the best energy absorption capability. Further, the relationship between the energy absorption properties and the configuration was captured using a modified symmetric radius basis function (RBF) surrogate model showing higher computational efficiency and approximately equal accuracy compared to the original RBF model. The nondominated sorting genetic algorithm II (NSGA-II) was carried out to obtain the Pareto optimal set, rendering the EBCC structure with balanced properties of high specific energy absorption and low peak crushing force. This work presents a first effort in optimizing the energy absorption of lattice structures through pattern recognition, thus expanding the approaches for designing new lattice structures. [Display omitted] [ABSTRACT FROM AUTHOR]

Lattice structures have gained larger design space and wider application in aerospace, automobile, civil and other engineering fields due to the advancements in additive manufacturing (AM) technology. Seeking the optimal lattice structure configuration for the purpose of enhancing mechanical performance holds paramount importance. The hollow lattice structure possesses high material utilization efficiency, but often suffers from premature failure at the node interconnections. In this paper we propose a partially hollow lattice structure (PHBCC) with solidified nodes and capsule-shaped cavities in the middle of truss components. Quasi-static compression tests were performed on the partially hollow body-centered cubic (BCC) lattices manufactured via selective laser melting technology (SLM). The effects of various geometric parameters were analyzed through finite element simulations. The findings demonstrate that the introduced PHBCC lattice exhibits enhanced mechanical properties. Specifically, there is an observed increase of 92%, 51.9%, and 22.8% in terms of specific stiffness, specific strength, and specific energy absorption, respectively, in comparison to the conventional BCC and hollow BCC (HBCC) structure. Notably, the proposed PHBCC lattice displays superior energy absorption capacity compared to a majority of existing lattice structures. • A lattice structure with solidified nodes and hollow truss components is proposed. • More uniform stress distribution is achieved compared with conventional BCC lattice. • Higher specific modulus and higher specific strength are achieved compared with conventional BCC lattice. • Higher plateau stress and higher specific energy absorption are achieved compared with other architected structures. [ABSTRACT FROM AUTHOR]

Hybridization is an effective approach to designing new lattice structures. In this paper, a novel hybrid lattice design is proposed with nested cell topology combining inner stretching-dominated struts and outer bending-dominated struts. Two hybrid lattices have been created, i.e., HS1 with inner G7 and outer octagonal cell topology, and HS2 with inner simple cubic (SC) and outer octagonal cell topology. Extensive finite element (FE) simulations were carried out to compare the compression performances of the proposed HS1 and HS2 lattices with those of the octet and octagonal lattices. The accuracy of the FE simulations was verified by energy absorption theory and comparison with experimental results in the literature. The results show that the proposed HS2 lattice possesses the best energy absorption performance. Under the same relative density conditions, the energy absorption (EA) capacity of the HS2 lattice exceeds the traditional octagonal and octet lattices by 30% and 42%, respectively. The compression stability of the hybrid lattices is also improved, which can be attributed to the simultaneous collapse pattern instead of the layer-by-layer collapse pattern and the more uniform stress distribution. In addition, the effects of geometrical deviation coefficient m of the hybrid lattices and the loading direction have also been investigated through a parametric study. It is found that the HS2 lattice achieves the maximum EA capacity at an intermediate m value of 0.5, and exhibits anisotropic responses in terms of the deformation pattern and the energy absorption efficiency under different loading directions. [ABSTRACT FROM AUTHOR]

• Gradient lattice structures were designed by gradiently varying the BCC cell center vertex. • Python script was employed to architect lattice structures with different gradient. • Multi-jet Fusion technique was used to fabricate gradient lattice samples with PA 12. • Topology gradient can change the deformation mode and improve the mechanical properties. Lattice structures have been widely used in biomedicine, transportation, infrastructure, and other engineering fields due to their high specific strength, strong energy absorption capacity, and tunable mechanical property. Existing researches mainly focus on the uniform lattice structure or gradient lattice structure with varying density, with the design potential of lattice structure not fully exploited. In this study, inspired by the functionally graded material, a novel topologically gradient lattice structure with varying cell topology is proposed to realize spacial adjustability of the mechanical properties. The new lattice structure evolves from the classical body-centered cubic (BCC) lattice, with the body center positions varying gradiently from cell to cell along the specified directions. The prototypes of the new lattice are additively manufactured by the Multi-Jet Fusion (MJF) technology and quasi-statically compressed by the universal testing machines. Experimental and numerical simulation results reveal that the proposed structure topology gradient can significantly improve both the stiffness and the energy absorption capacity compared with the classical BCC lattice structures. It is found that the mechanical properties of the topologically gradient lattice structures are sensitive to the gradient direction, the gradient magnitude and the loading direction. This study expands the design space of lattice structures by introducing the topology gradient of the composing cells across the space. In this way, further improvement in the mechanical properties of lightweight lattice structures can be achieved. [ABSTRACT FROM AUTHOR]

• Novel lattice structures with twin boundaries were designed by mimicking twining micro structures of triclinic crystal system. • Python scripts were developed to automatically architect lattice structures with different twin boundary densities. • Introducing twin boundaries can control the deformation mode and enhance the energy absorption capacity of triclinic lattice structures. • Plateau stresses versus equivalent grain size obeys Hall-Petch relationship. Inspired by the microstructure of the triclinic crystal material, in this work we designed triclinic lattice structures (TC) with twin boundaries for energy absorption application. The deformation mode and energy absorption capacity of TCs under the quasi-static compression are investigated by finite element method, which is validated by the experiments on the TC specimen additively manufactured by the selective laser sintering (SLS) method. The TC design is further extended to the triclinic body-centered cubic lattice structures (TBCC). The results indicate that introducing twin boundaries into the lattice structure can control the deformation mode and thus improve the energy absorption performance. The energy absorption increases with the number of twin boundaries in both TCs and TBCCs. In addition, the plateau stress and the equivalent grain size of the proposed structures are found to also obey the Hall-Petch relationship that is prevalent in the polycrystal materials. This work verifies the feasibility of the approach of designing novel lattice structures by mimicking the material microstructures. [ABSTRACT FROM AUTHOR]