Micromechanical analysis of the effective properties of lattice structures in additive manufacturing

Souza, J. A.; Großmann, A.; Mittelstedt, Christian

doi:10.1016/j.addma.2018.07.007

Cited by 37 publications

(20 citation statements)

References 9 publications

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“…For comparison purposes, the analytical model described by Souza et al [11] is exemplarily used. It determines the relationship between aspect ratio, strut diameter, and mechanical properties for a given cellular structure, whereby the cell struts are considered as Timoshenko beams [41] in order to cover high to low aspect ratios.…”

Section: Methodsmentioning

confidence: 99%

“…For the sake of brevity, the way the model works is shortly summed up. Please refer to the corresponding publication for more details [11]. The analytical model consists of a strain energy based homogenization scheme of the representative volume element (RVE) in the linear elastic domain.…”

Section: Methodsmentioning

confidence: 99%

“…Predictive modelling of such structures is the main challenge here. Available analytical models [7][8][9][10][11] are subject to relatively high deviations from experiments [12] due to modelling assumptions that do not take into account the systematic manufacturing defects [13,14]. Alternative approaches try to follow a more pragmatic approach, i.e., based on semi-empirical finite element models to account for manufacturing parameters and their influence on resulting lattice quality, mechanical performance is predicted [15].…”

Section: Introductionmentioning

confidence: 99%

“…Understanding this complex interaction between process parameters, microstructures and material properties is essential for prediction of the structural behavior of additive manufactured parts and in particular of thin walled and lattice structures. In the present study, an approach bridging several scales is proposed based on data being recompiled from previous work for the purpose of this investigation [11,[35][36][37][38][39]. This contribution is divided into various parts, where experimental and analytical methods are in focus.…”

Section: Introductionmentioning

confidence: 99%

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Influence of the Miniaturisation Effect on the Effective Stiffness of Lattice Structures in Additive Manufacturing

Meyer

Brenne

Niendorf

et al. 2020

Metals

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Thin-walled and cellular structures are characterised by superior lightweight potential due to their advantageous stiffness to weight ratio. They find particular interest in the field of additive manufacturing due to robust and reproducible manufacturability. However, the mechanical performance of such structures strongly depends on the manufacturing process and resultant geometrical imperfections such as porosity, deviations in strut thickness or surface roughness, for which an understanding of their influence is crucially needed. So far, many authors conducted empirical investigations, while analytical methods are rarely applied. In order to obtain efficient design rules considering both mechanical properties and process induced characteristics, analytical descriptions are desirable though. Available analytical models for the determination of effective properties are mostly based on the simple advancement of beam theories, mostly ignoring manufacturing characteristics that, however, strongly influence the mechanical properties of additive manufactured thin-walled structures. One example is the miniaturisation effect, a microstructural effect that has been identified as one of the main drivers of the effective elasto-plastic properties of lightweight structures processed by additive manufacturing. The current work highlights the need to quantify further microstructural effects and to encourage combining them into mesostructural approaches in order to assess macrostructural effective properties. This multi-scale analysis of lattice structures is performed through a comparison between effective stiffness calculated through an analytical approach and compression tests of lattice structures, coupled with an investigation of the arrangement of their struts. In order to cover different potential loading scenarios, bending-dominated and stretch-dominated lattice structures made of the commonly used materials 316L and Ti6Al4V are considered, whereby the impact of microstructural phase transformation during processing is taken into account.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Influence of the Miniaturisation Effect on the Effective Stiffness of Lattice Structures in Additive Manufacturing

Meyer

Brenne

Niendorf

et al. 2020

Metals

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“…Their results showed that the relative density and topology of unit cell considerably affect the mechanical behavior of structures. Souza et al 15 proposed a closed-form analytical solution to determine effective properties of additively manufactured microstructures. A comparison between experimental results and proposed analytical solution showed excellent agreement for relative densities lower than 40%.…”

Section: Introductionmentioning

confidence: 99%

Architected functionally graded porous lattice structures for optimized elastic-plastic behavior

Mahbod

Asgari

Mittelstedt

2020

Proceedings of the Institution of Mechanical Engineers, Part L:

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In this paper, the elastic–plastic mechanical properties of regular and functionally graded additively manufactured porous structures made by a double pyramid dodecahedron unit cell are investigated. The elastic moduli and also energy absorption are evaluated via finite element analysis. Experimental compression tests are performed which demonstrated the accuracy of numerical simulations. Next, single and multi-objective optimizations are performed in order to propose optimized structural designs. Surrogated models are developed for both elastic and plastic mechanical properties. The results show that elastic moduli and the plastic behavior of the lattice structures are considerably affected by the cell geometry and relative density of layers. Consequently, the optimization leads to a significantly better performance of both regular and functionally graded porous structures. The optimization of regular lattice structures leads to great improvement in both elastic and plastic properties. Specific energy absorption, maximum stress, and the elastic moduli in x- and y-directions are improved by 24%, 79%, 56%, and 9%, respectively, compared to the base model. In addition, in the functionally graded optimized models, specific energy absorption and normalized maximum stress are improved by 64% and 56%, respectively, in comparison with the base models.

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RVE-based grading of truss lattice cores in sandwich panels

2023

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Additive manufacturing enables the fabrication of strut-based lattices that consist of periodic representative volume elements (RVE) and can be used as cores in sandwich panels. Due to the design freedom provided by additive manufacturing, the lattice strut diameter may vary through the lattice. Thus, the diameter distribution can be adapted to the stress variation in the sandwich core to achieve an efficient core design and avoid oversizing the core. Such grading approaches are required when the core is subjected to localized loads, e.g., near support points and load application areas. In this work, an analytical model is derived to determine stresses and deformations in lattice struts of RVE-based graded lattice cores in elastic sandwich panels using homogenization and dehomogenization methods. In contrast to already available models, the analytical model presented in this work allows grading the lattice strut diameter both along the sandwich length and through the core thickness. Furthermore, local stresses in the lattice struts caused by concentrated load application can be captured adequately by the present model. To highlight the benefits of graded cores, the strut stress distribution in graded cores is compared to the stress distribution in homogeneous cores.

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Micromechanical analysis of the effective properties of lattice structures in additive manufacturing

Cited by 37 publications

References 9 publications

Influence of the Miniaturisation Effect on the Effective Stiffness of Lattice Structures in Additive Manufacturing

Influence of the Miniaturisation Effect on the Effective Stiffness of Lattice Structures in Additive Manufacturing

Architected functionally graded porous lattice structures for optimized elastic-plastic behavior

RVE-based grading of truss lattice cores in sandwich panels

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