Development and characterisation of novel three-dimensional axisymmetric chiral auxetic structures

Novak, Nejc; Mauko, Anja; Ulbin, Miran; Krstulović‐Opara, Lovre; Ren, Zoran

doi:10.1016/j.jmrt.2022.02.025

Cited by 28 publications

(18 citation statements)

References 40 publications

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“…The mass normalized mechanical responses of different ACS geometries are shown in Figure 7 a. The responses of initial non‐graded ACS and the primitively graded ACS geometries are taken from [ 33 ] and are shown in gray (different gradation strategies) and black curves in Figure 7a. The optimized ACS provides a much stiffer response with delayed densification than the other geometries, Figure 7a.…”

Section: Resultsmentioning

confidence: 99%

“…The ACS with a cylindrical shape was presented in the previous work [ 33 ] and the patent is currently pending at the European patent office. [ 37 ] The ACS was built from the regular tetrachiral unit cells with their shape corresponding to the 10 th eigenmode of the regular cubic unit cell, presented in ref.…”

Section: Methodsmentioning

confidence: 99%

“…Six samples were fabricated from gas atomized stainless steel 316 L powder using the additive manufacturing machine EOS M280 based on a powder bed fusion system and used for the initial experimental testing, reported in the previous work. [ 33 ] The physical properties of the samples are given in Table 1 . Uniaxial compression tests were performed using a servo‐hydraulic INSTRON 8801 testing machine with a position‐controlled cross‐head rate of 0.1 mm s −1 .…”

Section: Methodsmentioning

confidence: 99%

“…The Poisson's ratio was measured in the experiments using digital image correlation (DIC), where the method was tracking the edge of the compressed sample, which is explained in ref. [33]. The Poisson's ratio in the computational models was measured on one side of the sample (due to the axial symmetry) in points marked in Figure 2, which represents the outermost edge of the structure.…”

Section: Methodsmentioning

confidence: 99%

“…ACS's mechanical behavior and energy absorption capabilities can be further enhanced with the introduction of graded porosity. [ 33 ] This can be done in a trivial trial‐and‐error approach as presented in ref. [33] with discrete concentric regions of different strut thicknesses or more sophisticatedly by applying structural optimization.…”

Section: Introductionmentioning

confidence: 99%

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Structural Optimization of the Novel 3D Graded Axisymmetric Chiral Auxetic Structure

Novak

Nowak

Vesenjak

et al. 2022

Physica Status Solidi (b)

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A recently introduced novel 3D auxetic axisymmetric chiral structure (ACS) with a periodic structure exhibits nonuniform stress distribution, with stresses concentrated primarily on the inner part of the structure. The structural optimization of one unit cell of the validated computational model is conducted to determine the optimal geometrical configuration of the unit cell, considering the target strain energy density as the optimization objective function. The results of the unit cell optimization are then used to build the parametric computational model of the whole ACS structure, where the areas of the significantly different strut thicknesses are defined as a separate section to control the thickness of the struts discretely. The parametric computational model is then optimized. This results in a new, spatially graded ACS with a stiffer structure, providing 4.25 times higher energy absorption capability than regular ACS, with one of the highest specific energy absorption (SEA) values in the strut‐based metamaterial class and thus ideal for future crash absorption applications.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Structural Optimization of the Novel 3D Graded Axisymmetric Chiral Auxetic Structure

Novak

Nowak

Vesenjak

et al. 2022

Physica Status Solidi (b)

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Numerical Prediction of the Yield Surface of a Chiral Auxetic Structure

Kose,

Novak,

Grednev

et al. 2023

Adv Eng Mater

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For today’s requirements, the material itself is often not sufficient anymore. This leads to structural cellular materials and metamaterials, which allow for more degrees of freedom by a strong structure‐property‐relationship. Auxetic structures investigated in this contribution belong to metamaterials. Auxetic metamaterials show huge advantages in their properties, e.g. an enhanced specific energy absorption capacity as well as a negative Poisson’s ratio, combined with a very high stiffness‐to‐weight ratio. Experimental probing of these structures is very challenging, hence, up to now, auxetic materials are only investigated in uniaxial, bending or shear loading. But for an industrial application, the knowledge of the multiaxial yield behaviour is inevitable. For the first time, the present study deals with the numerical probing of the yield surface for a chiral auxetic structure applying multiaxial loading. The changes in Poisson’s ratio, specific energy absorption capacity and the resulting non‐convex yield surface are studied numerically. It showed, that the highest specific energy absorption capacities are reached under compression load cases while higher stiffnesses and yield stresses are achieved under tensile loading. There is a strong‐structure‐property relationship and load case dependency for the Poisson’s ratio as well as for the specific energy absorption capacity.This article is protected by copyright. All rights reserved.

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Generative Lattice Units with 3D Diffusion for Inverse Design: GLU3D

Jadhav,

Berthel,

et al. 2024

Adv Funct Materials

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Architected materials, exhibiting unique mechanical properties derived from their designs, have seen significant growth due to the design versatility and cost‐effectiveness offered by additive manufacturing. While finite element methods accurately evaluate the mechanical response of these structures, identifying new designs exhibiting specific mechanical properties remains challenging, often requiring computationally expensive simulations and design expertise. This underscores the need for a framework that generates structures based on desired mechanical properties without requiring expert input. In this work, a novel denoising diffusion‐based model is presented that generates complex lattice unit cell structures based on desired mechanical properties, manufacturable via additive techniques. The proposed framework generates unique lattice unit cell structures in the implicit domain which can be easily converted to mesh structures for fabrication and voxel structures for structural analysis. The proposed model accelerates the design process by generating unique structures with both isotropic and anisotropic stiffness, outperforming traditional unit cells like simple cubic and body‐centered‐cubic in energy absorption and compression load at lower densities. Additionally, this work explores a new class of hybrid structures, derived by combining multiple configurations of triply periodic minimal surface structures using non‐linear transition functions, which may offer equivalent or enhanced strength compared to conventional designs.

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Development and characterisation of novel three-dimensional axisymmetric chiral auxetic structures

Cited by 28 publications

References 40 publications

Structural Optimization of the Novel 3D Graded Axisymmetric Chiral Auxetic Structure

Structural Optimization of the Novel 3D Graded Axisymmetric Chiral Auxetic Structure

Numerical Prediction of the Yield Surface of a Chiral Auxetic Structure

Generative Lattice Units with 3D Diffusion for Inverse Design: GLU3D

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