5,310 research outputs found

    CFD Modeling of the Flow of Resin into a Preform Mold of Carbon Fibers

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    Sandwich structures are formed by separating load bearing face sheets with a light weight core material. This type of structural design is both strong and light, making for an extremely efficient structure. Sustainable sandwich structures made using face sheets of natural fiber mats and natural oil based resins separated by a fungal mycelia core. The vacuum infusion of resin into the fiber mats is investigated numerically using Star CCM+, a computational fluid dynamics (CFD) package. The methodology focuses on ease of use while emphasizing good modeling practices. The models generated are compared to the experimental results and provide a theoretical foundation for mold geometries conducive to even resin infusion

    A comparison of hole-filling methods in 3D

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    This paper presents a review of the most relevant current techniques that deal with hole-filling in 3D models. Contrary to earlier reports, which approach mesh repairing in a sparse and global manner, the objective of this review is twofold. First, a specific and comprehensive review of hole-filling techniques (as a relevant part in the field of mesh repairing) is carried out. We present a brief summary of each technique with attention paid to its algorithmic essence, main contributions and limitations. Second, a solid comparison between 34 methods is established. To do this, we define 19 possible meaningful features and properties that can be found in a generic hole-filling process. Then, we use these features to assess the virtues and deficiencies of the method and to build comparative tables. The purpose of this review is to make a comparative hole-filling state-of-the-art available to researchers, showing pros and cons in a common framework.• Ministerio de Economía y Competitividad: Proyecto DPI2013-43344-R (I+D+i) • Gobierno de Castilla-La Mancha: Proyecto PEII-2014-017-PpeerReviewe

    Probabilistic Analysis Of Property Uncertainties Using Resin Infusion Flow Modeling And Simulations €“ Resin Viscosity And Preform Permeability

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    Physics based flow modeling provides an effective way to simulate the resin infusion process in liquid composite molding processes for polymer composite structures. These are effective to provide optimal injection time and locations for given process parameters of resin viscosity and preform permeability prior to resin gelation. However, there could be significant variations in these two parameters during actual manufacturing due to differences in the resin batches, mixes, temperature, ambient conditions for viscosity; in the preform rolls, compaction, etc., for permeability

    GTTC Future of Ground Testing Meta-Analysis of 20 Documents

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    National research, development, test, and evaluation ground testing capabilities in the United States are at risk. There is a lack of vision and consensus on what is and will be needed, contributing to a significant threat that ground test capabilities may not be able to meet the national security and industrial needs of the future. To support future decisions, the AIAA Ground Testing Technical Committees (GTTC) Future of Ground Test (FoGT) Working Group selected and reviewed 20 seminal documents related to the application and direction of ground testing. Each document was reviewed, with the content main points collected and organized into sections in the form of a gap analysis current state, future state, major challenges/gaps, and recommendations. This paper includes key findings and selected commentary by an editing team

    Marshall Space Flight Center Research and Technology Report 2019

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    Today, our calling to explore is greater than ever before, and here at Marshall Space Flight Centerwe make human deep space exploration possible. A key goal for Artemis is demonstrating and perfecting capabilities on the Moon for technologies needed for humans to get to Mars. This years report features 10 of the Agencys 16 Technology Areas, and I am proud of Marshalls role in creating solutions for so many of these daunting technical challenges. Many of these projects will lead to sustainable in-space architecture for human space exploration that will allow us to travel to the Moon, on to Mars, and beyond. Others are developing new scientific instruments capable of providing an unprecedented glimpse into our universe. NASA has led the charge in space exploration for more than six decades, and through the Artemis program we will help build on our work in low Earth orbit and pave the way to the Moon and Mars. At Marshall, we leverage the skills and interest of the international community to conduct scientific research, develop and demonstrate technology, and train international crews to operate further from Earth for longer periods of time than ever before first at the lunar surface, then on to our next giant leap, human exploration of Mars. While each project in this report seeks to advance new technology and challenge conventions, it is important to recognize the diversity of activities and people supporting our mission. This report not only showcases the Centers capabilities and our partnerships, it also highlights the progress our people have achieved in the past year. These scientists, researchers and innovators are why Marshall and NASA will continue to be a leader in innovation, exploration, and discovery for years to come

    Analysing the impact of data quality and processing techniques on the accuracy of virtual reconstruction - a case study of a deactivated grain milling factory

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    Mestrado de dupla diplomação com a Associação Educativa Evangélica - UniEvangélicaThis research work focuses on the digitalization of an ancient grain grinding machine using a 3D scanner. The preservation of cultural heritage, specifically in the field of industrial archaeology, is the main objective of this study. By employing advanced 3D scanning technology, the machine was captured in high resolution to create a virtual reconstruction. The process involved utilizing a state-of-the-art 3D scanner to capture the intricate details and dimensions of the antique machine. The resulting three-dimensional model serves as a digital documentation of the artifact, enabling its preservation and analysis for future generations. The study encompasses various aspects through the generated 3D model, detailed investigations into the machine's mechanisms, components, and historical context are possible, shedding light on its functional and historical significance. Moreover, the digital restoration techniques applied in this research contribute to the preservation of the artifact's visual appearance, allowing for a virtual representation of its original state. This helps in visualizing the machine's original form and aids in understanding its intricate workings. The findings of this study have broader implications for the field of cultural heritage preservation. The digitization of historical artifacts using 3D scanning technology provides an innovative approach for documenting, studying, and disseminating knowledge about such artifacts. Additionally, it facilitates remote access and virtual exhibitions, ensuring the wider dissemination of cultural heritage to a global audience. This research work not only showcases the successful application of 3D scanning in preserving and studying an ancient grain grinding machine but also highlights the potential for further exploration and analysis of other industrial artifacts. The integration of advanced technologies and heritage preservation contributes to the understanding and appreciation of our industrial past, fostering a deeper connection with our cultural heritage.Este trabalho de pesquisa foca na digitalização de uma antiga máquina de moer grãos utilizando um scanner 3D. A preservação do patrimônio cultural, especificamente no campo da arqueologia industrial, é o principal objetivo deste estudo. Ao utilizar tecnologia avançada de escaneamento 3D, a máquina foi capturada em alta resolução para criar uma reconstrução virtual. O processo envolveu a utilização de um scanner 3D de ponta para capturar os detalhes e dimensões intrincados da máquina antiga. O modelo tridimensional resultante serve como documentação digital do artefato, permitindo sua preservação e análise para as gerações futuras. O estudo abrange vários aspectos através do modelo 3D gerado, investigações detalhadas sobre os mecanismos, componentes e contexto histórico da máquina são possíveis, lançando luz sobre sua importância funcional e histórica. Além disso, as técnicas de restauração digital aplicadas nesta pesquisa contribuem para a preservação da aparência visual do artefato, permitindo uma representação virtual de seu estado original. Isso ajuda na visualização da forma original da máquina e auxilia na compreensão de seu funcionamento intrincado. As descobertas deste estudo têm implicações mais amplas para o campo da preservação do patrimônio cultural. A digitalização de artefatos históricos utilizando tecnologia de escaneamento 3D oferece uma abordagem inovadora para documentar, estudar e disseminar conhecimento sobre esses artefatos. Além disso, facilita o acesso remoto e exposições virtuais, garantindo a ampla disseminação do patrimônio cultural para um público global. Este trabalho de pesquisa não apenas demonstra a aplicação bem-sucedida de escaneamento 3D na preservação e estudo de uma antiga máquina de moer grãos, mas também destaca o potencial para exploração e análise adicionais de outros artefatos industriais. A integração de tecnologias avançadas e preservação do patrimônio contribui para a compreensão e apreciação do nosso passado industrial, promovendo uma conexão mais profunda com nosso patrimônio cultural

    Vision 2040: A Roadmap for Integrated, Multiscale Modeling and Simulation of Materials and Systems

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    Over the last few decades, advances in high-performance computing, new materials characterization methods, and, more recently, an emphasis on integrated computational materials engineering (ICME) and additive manufacturing have been a catalyst for multiscale modeling and simulation-based design of materials and structures in the aerospace industry. While these advances have driven significant progress in the development of aerospace components and systems, that progress has been limited by persistent technology and infrastructure challenges that must be overcome to realize the full potential of integrated materials and systems design and simulation modeling throughout the supply chain. As a result, NASA's Transformational Tools and Technology (TTT) Project sponsored a study (performed by a diverse team led by Pratt & Whitney) to define the potential 25-year future state required for integrated multiscale modeling of materials and systems (e.g., load-bearing structures) to accelerate the pace and reduce the expense of innovation in future aerospace and aeronautical systems. This report describes the findings of this 2040 Vision study (e.g., the 2040 vision state; the required interdependent core technical work areas, Key Element (KE); identified gaps and actions to close those gaps; and major recommendations) which constitutes a community consensus document as it is a result of over 450 professionals input obtain via: 1) four society workshops (AIAA, NAFEMS, and two TMS), 2) community-wide survey, and 3) the establishment of 9 expert panels (one per KE) consisting on average of 10 non-team members from academia, government and industry to review, update content, and prioritize gaps and actions. The study envisions the development of a cyber-physical-social ecosystem comprised of experimentally verified and validated computational models, tools, and techniques, along with the associated digital tapestry, that impacts the entire supply chain to enable cost-effective, rapid, and revolutionary design of fit-for-purpose materials, components, and systems. Although the vision focused on aeronautics and space applications, it is believed that other engineering communities (e.g., automotive, biomedical, etc.) can benefit as well from the proposed framework with only minor modifications. Finally, it is TTT's hope and desire that this vision provides the strategic guidance to both public and private research and development decision makers to make the proposed 2040 vision state a reality and thereby provide a significant advancement in the United States global competitiveness

    Modeling multiphase flow and substrate deformation in nanoimprint manufacturing systems

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    Nanopatterns found in nature demonstrate that macroscopic properties of a surface are tied to its nano-scale structure. Tailoring the nanostructure allows those macroscopic surface properties to be engineered. However, a capability-gap in manufacturing technology inhibits mass-production of nanotechnologies based on simple, nanometer-scale surface patterns. This gap represents an opportunity for research and development of nanoimprint lithography (NIL) processes. NIL is a process for replicating patterns by imprinting a fluid layer with a solid, nano-patterned template, after which ultraviolet cure solidifies the fluid resulting in a nano-patterned surface. Although NIL has been demonstrated to replicate pattern features as small as 4 nm, there are significant challenges in using it to produce nanotechnology. Ink-jet deposition methods deliver the small fluid volumes necessary to produce the nanopattern, and drop volumes can be tuned to what the pattern requires. However the drops trap pockets of gas as they merge and fill the template, and due to relatively slow gas dissolution, reduce processing throughput. Capillary forces that arise from the gas-liquid interfaces drive non-uniform gap closure and the resulting variations in residual layer reduces process yield or degrades product performance. This thesis develops reduced-order models for fluid flow and structural mechanics of the imprint process for NIL. Understanding key phenomena of gas trapping and residual layer non-uniformity drives model development to better understand how throughput and yield can be improved. Reynolds lubrication theory, the \textit{disperse} type of multiphase flow, and a lumped-parameter model of dissolution unite to produce a two-phase flow model for NIL simulations of 10,000 drops per cm2\text{cm}^2. Qualitative agreement between simulation and experiment provides a modicum of validation of this model for flow in NIL simulations. The two-phase model simulations predicts that both dissolution and viscous resistance affect throughput. The coupling of a reduced-order model for 3D structural mechanics with the two-phase flow model enables simulations of drop merger on a free-span tensioned web. Challenges in improving the structural model lead to formulation of a 2D model for which sources of instability are more easily discovered and understood. Inextensible cylindrical shell theory and lubrication theory combine into a model for the elastohydrodynamics of a rolling-imprint modality of NIL. Foil-bearing theory describes the lubrication layer that forms between a thin, tensioned web moving past another surface. Reproduction of the results of foil-bearing theory validates this coupled model and reveals a highly predictable region of uniformity that provides low shear stress conditions ideal for UV-cure. These results show theoretical limitations that are used to construct a processing window for predicting process feasibility
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