2,877 research outputs found

    Behavior modeling for the spraying device in the layered manufacturing process

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    Published ArticleA component, which has a perfect combination of different materials (probably including homogeneous materials and three different types of heterogeneous materials) in its different portions for a specific application, is considered as the component made of a multiphase perfect material. To fabricate such components, a hybrid layered manufacturing process has been developed. In order to accurately spray different materials with their required volume fractions for every pixel during fabrication, it is important to investigate its spraying operation. This paper establishes the behavior model of the spraying device and proves its validity using digital simulations

    Behavior modeling for the spraying device in the layered manufacturing process for the components made of a multiphase perfect material

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    A component, which has a perfect combination of different materials (probably including homogeneous materials and three different types of heterogeneous materials) in its different portions for a specific application, is considered as the component made of a multiphase perfect material. To fabricate such components, a hybrid layered manufacturing process has been developed. In order to accurately spray different materials with their required volume fractions for every pixel during fabrication, it is important to investigate its spraying operation. This paper establishes the behavior model of the spraying device and proves its validity using digital simulations.published_or_final_versio

    CFD modelling of a mixing chamber for the realisation of functionally graded scaffolds

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    Biological tissues are characterised by spatially distributed gradients, intricately linked with functions. It is widely accepted that ideal tissue engineered scaffolds should exhibit similar functional gradients to promote successful tissue regeneration. Focusing on bone, in previous work we proposed simple methods to obtain osteochondral functionally graded scaffolds (FGSs), starting from homogeneous suspensions of hydroxyapatite (HA) particles in gelatin solutions. With the main aim of developing an automated device to fabricate FGSs, this work is focused on designing a stirred tank to obtain homogeneous HA-gelatin suspensions. The HA particles transport within the gelatin solution was investigated through computational fluid dynamics (CFD) modelling. First, the steady-state flow field was solved for the continuous phase only. Then, it was used as a starting point for solving the multi-phase transient simulation. CFD results showed that the proposed tank geometry and setup allow for obtaining a homogeneous suspension of HA micro-particles within the gelatin solution

    Research and Education in Computational Science and Engineering

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    Over the past two decades the field of computational science and engineering (CSE) has penetrated both basic and applied research in academia, industry, and laboratories to advance discovery, optimize systems, support decision-makers, and educate the scientific and engineering workforce. Informed by centuries of theory and experiment, CSE performs computational experiments to answer questions that neither theory nor experiment alone is equipped to answer. CSE provides scientists and engineers of all persuasions with algorithmic inventions and software systems that transcend disciplines and scales. Carried on a wave of digital technology, CSE brings the power of parallelism to bear on troves of data. Mathematics-based advanced computing has become a prevalent means of discovery and innovation in essentially all areas of science, engineering, technology, and society; and the CSE community is at the core of this transformation. However, a combination of disruptive developments---including the architectural complexity of extreme-scale computing, the data revolution that engulfs the planet, and the specialization required to follow the applications to new frontiers---is redefining the scope and reach of the CSE endeavor. This report describes the rapid expansion of CSE and the challenges to sustaining its bold advances. The report also presents strategies and directions for CSE research and education for the next decade.Comment: Major revision, to appear in SIAM Revie

    Review of the Synergies Between Computational Modeling and Experimental Characterization of Materials Across Length Scales

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    With the increasing interplay between experimental and computational approaches at multiple length scales, new research directions are emerging in materials science and computational mechanics. Such cooperative interactions find many applications in the development, characterization and design of complex material systems. This manuscript provides a broad and comprehensive overview of recent trends where predictive modeling capabilities are developed in conjunction with experiments and advanced characterization to gain a greater insight into structure-properties relationships and study various physical phenomena and mechanisms. The focus of this review is on the intersections of multiscale materials experiments and modeling relevant to the materials mechanics community. After a general discussion on the perspective from various communities, the article focuses on the latest experimental and theoretical opportunities. Emphasis is given to the role of experiments in multiscale models, including insights into how computations can be used as discovery tools for materials engineering, rather than to "simply" support experimental work. This is illustrated by examples from several application areas on structural materials. This manuscript ends with a discussion on some problems and open scientific questions that are being explored in order to advance this relatively new field of research.Comment: 25 pages, 11 figures, review article accepted for publication in J. Mater. Sc

    Methods for Characterizing Multiphase Magnetocaloric Materials

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    This thesis is aimed to study the characteristics of thermomagnetic phase transitions and the resulting magnetocaloric effect in multiphase magnetocaloric materials, which is a very common scenario in the research of the magnetocaloric effect and can lead to complex situations that need to be properly approached. On the one hand, composites that combine various phases with Curie transitions close to each other are interesting and highly studied as they can lead to an enhanced refrigerant capacity with respect to the pure phases while keeping a large enough response. In this thesis, newly developed Gd + Gd7Pd3 composites are presented as a case in which the mentioned improvement of the refrigerant capacity is achieved. This intentional situation of overlapping Curie transitions has been used for the development of a method for the deconvolution of the magnetocaloric responses by means of the scaling laws of the magnetocaloric effect. On the other hand, materials exhibiting magnetostructural transformation (first-order phase transition) can also show the Curie transitions of the phases (second-order phase transition), where the phase transitions of different type can be concurrent. This situation is approached using Heusler alloys undergoing magnetostructural transformation located close to the Curie transitions of the martensitic and austenitic phases. The competing effect of both types of phase transitions in this case is investigated by experimental and analytical methods. The deconvolution method used for the composites is successfully applied here, enabling the subtraction of the Curie transition to the total response. It has to be noted that these situations of overlapping phase transitions can also occur unintentionally (i.e., due to the presence of impurities during synthesis). Therefore, the developed methods can also be used in these situations to know the effect of additional phase transitions and to gauge the actual response of the desired phase. Additionally, it has also been shown how the overlapping Curie transitions of the phases affect the hysteretic signature of the alloys undergoing magnetostructural transformation. This study is addressed through the emerging Temperature first-order reversal curves (TFORC) method for the study of magnetocaloric materials, using again Heusler alloys as a model case. This part combines experimental results with results from the modelling of the thermomagnetic behavior of the material. This has enabled a direct correlation between the characteristics of the thermomagnetic behavior of the alloys and the features of the TFORC distributions. Finally, the emerging topic of using polymer-based composites for the 3D printing of functional parts is addressed. Here, the main existing problem lies in the fabrication of uniform composite materials that allow the 3D printing of parts with predictable and repeatable functionality without relying on industrial techniques. A novel manufacturing method of polymer-based filaments containing functional fillers is proposed. Soft-magnetic steel particles have been used to manufacture polymer-based magnetic composites as proof of concept of the validity of the method. Once validated, the method is used to manufacture polymer-based magnetocaloric composites for additive manufacturing. The relatively simple method provides highly homogeneous filaments that preserve the magnetic functionality of the fillers. However, the property of the polymeric matrix is significantly affected by the addition of the metallic fillers, which has an important influence on the processability parameters both for the extrusion and printing

    Simulation-Based Innovation and Discovery: Energetics Applications

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