Composite Materials
Viktor Gribniak
Abstract
The modern industry allows producing composite materials with a broad spectrum of mechanical properties applicable in medicine, aviation, and automotive industries. However, the building industry generates a substantial part of budgets worldwide and utilizes vast material amounts. At the same time, the ...
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The modern industry allows producing composite materials with a broad spectrum of mechanical properties applicable in medicine, aviation, and automotive industries. However, the building industry generates a substantial part of budgets worldwide and utilizes vast material amounts. At the same time, the engineering practice has revealed that innovative technologies require new design concepts related to developing materials with mechanical properties tailored for structural purposes. It is the opposite of the current design philosophy when design solutions allow applying only the existing typical materials, the physical characteristics of which, in general, are imperfectly suiting the technical requirements, leading to an inefficient increase of the material amounts for safety’s sake. Moreover, some structural solutions are barely possible using standardized approaches. The “Industrialised material-oriented engineering for eco-optimized structures” research project supported by the European Regional Development Fund inspired this article’s emergence, which adapts the Award lecture at the European Advanced Material Congress 2022 in Genoa. It summarizes the project results and illustrates the implementation of the proposed adaptive design concept.
Ihssan Hendi; Matthieu Blaise; Gaétan Schneider; Manuel Fendler
Abstract
Printed electronics can be considered as an additive manufacturing technique allowing the fabrication of circuits and devices such as sensors, MEMS, LEDs, etc. An important research subject in this field is identifying new materials exhibiting low resistivity. In this article, we present a new copper ...
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Printed electronics can be considered as an additive manufacturing technique allowing the fabrication of circuits and devices such as sensors, MEMS, LEDs, etc. An important research subject in this field is identifying new materials exhibiting low resistivity. In this article, we present a new copper paste interesting for structural electronics, based on additive manufacturing and laser activation. We characterized the structure of this copper paste after laser activation, by SEM, EDS, and FTIR. We also used four probe method to characterize sheet resistance to obtain a resistivity as low as 10 -7 Ω.m, and compared it to other commercial conductive pastes.
Vittoria Laghi; Michele Palermo; Giada Gasparini; Valentina Alena Girelli; Tomaso Trombetti
Abstract
In the last decades Additive Manufacturing has gained fundamental importance in the development of digital fabrication for the automotive, aerospace, biomedical and only lately civil engineering field. In particular, the technology of Wire-and-Arc Additive Manufacturing, based on a welding process adopted ...
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In the last decades Additive Manufacturing has gained fundamental importance in the development of digital fabrication for the automotive, aerospace, biomedical and only lately civil engineering field. In particular, the technology of Wire-and-Arc Additive Manufacturing, based on a welding process adopted on a robotic arm, is the most suitable to realize structural elements which usually requires large dimensions of the printed outcome, with still a good mechanical response of the printed metal material. The authors have been part of a pioneering work which provides the first insight into the material and geometrical properties relevant to characterize 308LSi stainless steel elements to realize the first 3D-printed steel footbridge to be held in Amsterdam by 2020 and manufactured by the Dutch company MX3D. In detail, the work presents the first results of an intense geometrical study to characterize the intrinsic irregularities of the printed outcome, by means of hand measurements and high-precision 3D scan acquisition of different element types. Copyright © VBRI Press.
Hong-Cheol Kim; Da-Yeong Kim; Ji-Eun Lee; Keun Park
Abstract
According to recent advancements in additive manufacturing (AM) technology, also known as 3d printing, the role of AM has changed from the conventional rapid prototyping (RP) to direct fabrication of functional parts. The AM technology based on layer-by-layer manufacturing has a limitation in its poor ...
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According to recent advancements in additive manufacturing (AM) technology, also known as 3d printing, the role of AM has changed from the conventional rapid prototyping (RP) to direct fabrication of functional parts. The AM technology based on layer-by-layer manufacturing has a limitation in its poor surface finish and mechanical strength, especially along the thickness direction. This study proposes a new post-processing method for thermoplastic AM products with the goal of improving surface finish and mechanical strength. The proposed method, called constrained remelting, uses a metal mould with a negative shape that surrounds the printed polymer part. This mould is heated near the melting temperature of the polymer material so that the printed sample is melted and reshaped inside the mould. To evaluate changes in surface finish and mechanical strength, tensile specimens were printed and tested with various build directions; the tensile test revealed that the Z-directionally printed specimen had much lower mechanical strength than the specimens built along X- or Y- directions. Remelting experiments were then performed for the Z-directionally printed specimen under various remelting conditions (remelting temperature and initial thickness), and the resulting changes in surface finish and tensile strength were investigated. Among these remelting conditions, the 160°C remelting temperature and 4.0 mm thickness condition provided the best result where surface finish and tensile strength were improved significantly so as to be comparable to those of injection-moulded products.
Anna Okunkova; Sergey V. Fedorov;Andrey Gusarov; Marina Volosova; Pavel Peretyagin; Ivan Zhirnov; Pavel Podrabinnik
Abstract
In the article, the study of laser beam modulation influence on the structure of materials produced by one of the methods of additive manufacturing as selective laser melting (SLM) is provided. For the purpose of creating a smoother temperature gradient and the optimal conditions of the heat and mass ...
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In the article, the study of laser beam modulation influence on the structure of materials produced by one of the methods of additive manufacturing as selective laser melting (SLM) is provided. For the purpose of creating a smoother temperature gradient and the optimal conditions of the heat and mass transfer in the melting pool, an experimental stand for SLM-processing with the system of laser beam power density distribution modulation was created. The laser beam modulation gives promising results for higher parameters’ combinations such as power more than 150W and scanning velocity more than 50 mm/sec. The single track’s formation was produced by different power density distribution as Gaussian, Flat-top and Inverse Gaussian (Donut). All the received single tracks were studied with the use of optical and SEM microscopy. The results produce important data about reducing the width of powder consolidation zone, more even structure and higher productivity.
Nicola M. Everitt; Nesma T. Aboulkhair; Ian Maskery; Chris J. Tuck; Ian Ashcroft
Abstract
Single track and single layer AlSi 10Mg has been produced by selective laser melting (SLM) of alloy powder on an AlSi12 cast substrate. The SLM technique produced a cellular-dendritic ultra-fined grained microstructure. Chemical composition mapping and nanoindentation showed higher hardness in the SLM ...
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Single track and single layer AlSi 10Mg has been produced by selective laser melting (SLM) of alloy powder on an AlSi12 cast substrate. The SLM technique produced a cellular-dendritic ultra-fined grained microstructure. Chemical composition mapping and nanoindentation showed higher hardness in the SLM material compared to its cast counterpart. Importantly, although there was some increase of grain size at the edge of melt pools, nanoindentation showed that the hardness (i.e. yield strength) of the material was uniform across overlapping tracks. This is attributed to the very fine grain size and homogeneous distribution of Si throughout the SLM material.