Heterogeneities dominate mechanical performance of additively manufactured metal lattice struts

Dressler, Amber Dawn; Jost, Elliott; Miers, John C.; Moore, David G.; Seepersad, Carolyn Conner; Boyce, Brad Lee

doi:10.1016/j.addma.2019.06.011

Cited by 29 publications

(22 citation statements)

References 25 publications

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“…Some researchers investigate the defects of the structures fabricated by SLM or AM (additive manufacturing). It was noted that struts waviness, strut oversizing or strut thickness variation is prevalent on lattice structures fabricated by SLM [9,[37][38][39][40][41] with horizontal struts features showing more severe geometric imperfections than vertical struts and diagonal struts [9,39,41,42]. Moreover, vertical struts were found to be thinner than as-designed ones [9,37,39], and the magnitude of strut oversizing can change the failure mode from one to another [9].…”

Section: Introductionmentioning

confidence: 99%

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Investigation of Compressive and Tensile Behavior of Stainless Steel/Dissolvable Aluminum Bimetallic Composites by Finite Element Modeling and Digital Image Correlation

Ghasri-Khouzani

Bogno

et al. 2021

Materials

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This study reports fabrication, mechanical characterization, and finite element modeling of a novel lattice structure based bimetallic composite comprising 316L stainless steel and a functional dissolvable aluminum alloy. A net-shaped 316L stainless steel lattice structure composed of diamond unit cells was fabricated by selective laser melting (SLM). The cavities in the lattice structure were then filled through vacuum-assisted melt infiltration to form the bimetallic composite. The bulk aluminum sample was also cast using the same casting parameters for comparison. The compressive and tensile behavior of 316L stainless steel lattice, bulk dissolvable aluminum, and 316L stainless steel/dissolvable aluminum bimetallic composite is studied. Comparison between experimental, finite element analysis (FEA), and digital image correlation (DIC) results are also investigated in this study. There is no notable difference in the tensile behavior of the lattice and bimetallic composite because of the weak bonding in the interface between the two constituents of the bimetallic composite, limiting load transfer from the 316L stainless steel lattice to the dissolvable aluminum matrix. However, the aluminum matrix is vital in the compressive behavior of the bimetallic composite. The dissolvable aluminum showed higher Young’s modulus, yield stress, and ultimate stress than the lattice and composite in both tension and compression tests, but much less elongation. Moreover, FEA and DIC have been demonstrated to be effective and efficient methods to simulate, analyze, and verify the experimental results through juxtaposing curves on the plots and comparing strains of critical points by checking contour plots.

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Section: Introductionmentioning

confidence: 99%

“…SLM parameters also affect the mechanical properties of lattice structures [3,43]. Horizontal struts are the first to fracture, indicating they are experiencing greater stress than neighboring struts [41,44].…”

Section: Introductionmentioning

confidence: 99%

Investigation of Compressive and Tensile Behavior of Stainless Steel/Dissolvable Aluminum Bimetallic Composites by Finite Element Modeling and Digital Image Correlation

Ghasri-Khouzani

Bogno

et al. 2021

Materials

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“…The effective moduli of a periodic beam lattice can be derived using standard open-source software [11]. The morphology of actual cellular materials, however, in many cases deviates from the periodicity and there is a significant difference between "as-designed" and "as-manufactured" materials [12][13][14], vastly affecting their performance [2]. The corresponding knockdown of effective moduli owing to imperfections is, besides the aforementioned works, considered in [15] for three-dimensional foams, in [16] for beam lattices modeling twodimensional cellular materials, and in [6] for spring lattice systems.…”

Section: Introductionmentioning

confidence: 99%

Analysis of randomly damaged triangular beam lattice: elastic field and effective properties

Ryvkin

Cherkaev

2021

Mathematics and Mechanics of Solids

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The decay of elastic moduli of the triangular beam lattice with randomly missed links is studied. Random low-intensity damage is considered with no more than 10% of the links removed. Unidirectional and isotropic damage models are considered. Approximate analytical formulas for elastic moduli of damaged lattice are suggested and numerically verified. Models of isotropic and scalar damage are discussed; the variation of the Poisson coefficients as a result of damage is studied. Beams of different thicknesses are examined; the dependence of moduli on thickness is investigated. Random damage is simulated using a method based on the discrete Fourier transform; the mean value and standard deviation are calculated.

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“…It allows a larger freedom in designing parts but comes along with some limitations. Inherited defects such as a large surface roughness, a variable dimensional accuracy, and a characteristic porosity have been widely studied . The as‐built surface can be detrimental for lattice structures for which no machining can be used.…”

Section: Introductionmentioning

confidence: 99%

“…Inherited defects such as a large surface roughness, a variable dimensional accuracy, and a characteristic porosity have been widely studied. [13][14][15][16] The as-built surface can be detrimental for lattice structures for which no machining can be used. The discrimination of most detrimental defects for parts fabricated by E-PBF under tensile loading has been studied for fatigue applications.…”

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confidence: 99%

Surface Defects Sensitivity during the Unfolding of Corrugated Struts Made by Powder‐Bed Additive Manufacturing

et al. 2020

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Corrugated struts as part of lattice structures can lead to novel mechanical behavior by a combination of material and geometrical hardening. The unfolding behavior of such struts offers a potential of large macroscopic straining. However, their ability to be unfolded is impacted by the surface characteristics inherited from the additive manufacturing process. This study evaluates the unfolding sensitivity to these surface characteristics. Corrugated struts with varying surface roughness have been produced using a combination of Electron Beam Powder-Bed Fusion to produce corrugated samples with different nominal diameters, and chemical etching assisted by micro-CT to achieve a given final diameter. In-situ micro-CT tensile tests have been carried out to track the evolution of the struts morphology under loading. Surface defects play a significant role in the unfolding ability of such struts. They are characterized either by a global roughness or by a local notch depth. A quite broad unfolding dispersion remains for samples with the same level of roughness. A finer description of notch depth and location within the gauge length allows a more accurate prediction of the unfolding ability. A model for predicting the probability of failure during unfolding is presented.

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Heterogeneities dominate mechanical performance of additively manufactured metal lattice struts

Cited by 29 publications

References 25 publications

Investigation of Compressive and Tensile Behavior of Stainless Steel/Dissolvable Aluminum Bimetallic Composites by Finite Element Modeling and Digital Image Correlation

Investigation of Compressive and Tensile Behavior of Stainless Steel/Dissolvable Aluminum Bimetallic Composites by Finite Element Modeling and Digital Image Correlation

Analysis of randomly damaged triangular beam lattice: elastic field and effective properties

Surface Defects Sensitivity during the Unfolding of Corrugated Struts Made by Powder‐Bed Additive Manufacturing

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