Abstract
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.
Highlights
The aim of the present paper is to highlight the impact of the so-called miniaturisation effect, i.e., local texturing due to temperature gradients in lattice struts depending on the process parameters and geometrical input, on the elasto-plastic properties of additively manufactured lattice structures
The highest texture intensity is observed for the thinnest struts, resembling a strong texture
Souza et al [11] discussed that the formulation of shear loading used in the beam model applied may not be appropriate for low aspect ratios, for which the vicinity between strut-joints would render the beam theory obsolete
Summary
I.e., the 3D-printing technology, has found application in several industries, especially due to its flexibility and versatility enabling the realization of new design parts that cannot be achieved by the classical manufacturing processes on an economic basis [1,2].Thanks to its nature, the additive manufacturing process can offer tailored designs based on optimised geometries as an integral product, allowing a reduction of the single parts number and manufacturingMetals 2020, 10, 1442; doi:10.3390/met10111442 www.mdpi.com/journal/metalsMetals 2020, 10, x FOR PEER REVIEWMetals 2020, 10, 1442 to its nature, the additive manufacturing process can offer tailored designs based on optimised geometries as an integral product, allowing a reduction of the single parts number and manufacturing steps involved to in comparison to classicalmethods.construction where the steps involved in comparison classical construction Thismethods.is whereThis the is concepts of concepts of “individualization for free” andfor “complexity for free”are These derived from. I.e., the 3D-printing technology, has found application in several industries, especially due to its flexibility and versatility enabling the realization of new design parts that cannot be achieved by the classical manufacturing processes on an economic basis [1,2]. The additive manufacturing process can offer tailored designs based on optimised geometries as an integral product, allowing a reduction of the single parts number and manufacturing. Metals 2020, 10, 1442 to its nature, the additive manufacturing process can offer tailored designs based on optimised geometries as an integral product, allowing a reduction of the single parts number and manufacturing steps involved to in comparison to classicalmethods. Is whereThis the is concepts of concepts of “individualization for free” andfor “complexity for free”. “individualization for free” and “complexity free” are derived from
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