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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Bending Mechanics of Bio-mimetic Stiff Scale-Covered Plate

Sarkar, Pranta Rahman 01 January 2024 (has links) (PDF)
Biomimetic scale-covered systems offer immense potential and applications, particularly in soft robotics, protective armors, wearable materials, and multifunctional aerospace structures. A typical system consists of stiff rectangular plate like scales embedded in a softer media and arranged periodically. Experimentally, these systems indicate pronounced nonlinear strain stiffening behavior even when the underlying substrate strains are small. However, capturing these behaviors using commercial finite element (FE) codes has proved difficult due to multiple sliding contacts between the scales after engagement. Therefore, accurate and reliable analytical models of architecture-property-relationships are needed for analysis and design. This thesis investigates the contact kinematics and mechanics of biomimetic scale-covered plates subjected to bi-directional bending. Both synclastic and anti-clastic deformations of the plate are considered. The mechanical moment-curvature relationships are derived using the work-energy balance principle. The results show that when a plate is bent to a certain curvature, a quasi-rigid locked emerges for both synclastic and anticlastic curvature. Interestingly, while for anticlastic bending, the curvature at locking is nearly the same curvature as a beam with equivalent geometry and configuration, for synclastic bending, locking occurs significantly earlier due to cross-curvature effects. The moment-curvature relationships indicate strongly anisotropic behavior of the plate. The anisotropy itself was not constant, being strongly influenced by the state of deformation. The effect of scale arrangement parameters (lattice geometry) directly influenced the nonlinear behavior including the locked state. The analytical models developed are compared with equivalent FE analysis for validation for select cases and excellent agreements have been found. The outcome of this work would enhance the understanding of the nonlinear and anisotropic behavior of scale-covered plate systems, paving the way for systematic design and integration tailored for specific applications.
2

Um estudo sobre o design, a implementação e a avaliação de interfaces flexíveis para idosos em telefones celulares / A research on design, implementation and evaluation of flexible interfaces for the elderly in mobile phones

Gonçalves, Vinicius Pereira 16 April 2012 (has links)
A população idosa cresce no Brasil e cada vez mais se faz necessário desenvolver tecnologias de informação e comunicação adequadas a esse público. Com o barateamento dos telefones celulares, muitas famílias gostariam que seus idosos fossem usuários desses dispositivos visando ter contato com os mesmos quando esses estão fora de suas casas. No entanto, o design atual de celulares privilegia o público jovem, não levando em consideração as diferentes necessidades da população idosa. No mais, mesmo na população idosa, há diferenças com relação à escolaridade, experiência com tecnologias, habilidades cognitivas e destreza física. Este trabalho argumenta a favor do design, da implementação e da avaliação de interfaces que sejam flexíveis para atender à diversidade de requisitos dos idosos na interação com celulares. Uma abordagem para o design de interfaces de usuário flexíveis foi aplicada em um experimento exploratório e, considerando-se resultados de uma atividade estudo empírico com usuários idosos, um conjunto de normas que definem o design do comportamento flexível do sistema foi especificado. Esta dissertação propõe e apresenta um framework que propicia a reconfiguração de interfaces em tempo de interação, denominado de FlexInterface. Esse framework aborda o conceito de elementos da interface sendo, componentes que são carregados, instanciados e destruídos quando solicitados. Além disso, esta dissertação apresenta também uma abordagem que apoia a avaliação de interfaces flexíveis para idosos em telefones celulares. A abordagem analítica proposta, apresenta heurísticas específicas para esse contexto de uso. Por fim, uma avaliação com idosos foi realizada para verificar a viabilidade da proposta. Esse estudo constatou que houve uma redução no tempo de interação com o uso da interface flexível e um aumento na satisfação do usuário / The elderly population grows in Brazil and this fact increases the need to develop appropriate information and communication technologies to the public. As cell phones are getting cheaper, many families would like their elderly to be users of these devices aiming to have contact with them when they are out of their homes. However, the current cell phones design favors the younger people, not considering the different needs of the elderly population. At the most, even in the elderly population, there are differences regarding education, experience with technology, cognitive abilities and physical prowess. This dissertation argues for the design, implementation and evaluation of interfaces that are flexible to meet the diverse requirements of the elderly in the interaction with cell phones. One approach to the design of flexible user interfaces was applied in a case study and, considering the results of a practice with elderly users, a set of norms which define the design of the system flexible behavior was specified. This dissertation proposes and presents a framework that provides the interface reconfiguration during the interaction time, named FlexInterface. This framework addresses the concept of interface elements as components that are loaded, instantiated and destroyed when requested. Furthermore, this dissertation also brings an approachthat supports the evaluation of flexible interfaces for the elderly in mobile phones. The proposed analytical approach presents heuristics for this specific context of use. Finally, an assessment with elderly people was performed to verify the feasibility of the proposal. This study found that there was a reduction in the interaction time with the use of flexible interface and an increase in the users satisfaction
3

Estudo e proposta de um framework para o design de interfaces de usuario ajustaveis / Study and proposal of a framework for designing tailorable user interfaces

Neris, Vania Paula de Almeida 15 August 2018 (has links)
Orientador: Maria Cecilia Calani Baranauskas / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Computação / Made available in DSpace on 2018-08-15T21:05:28Z (GMT). No. of bitstreams: 1 Neris_VaniaPauladeAlmeida_D.pdf: 10009475 bytes, checksum: dcbce6609f994467e260e73be8f433fc (MD5) Previous issue date: 2010 / Resumo: A socialização dos sistemas computacionais trouxe um desafio a mais para os pesquisadores de Interação Humano-Computador: como prover interfaces que propiciem acesso ao maior número possível de usuários independentemente de suas capacidades sensoriais, físicas, cognitivas e emocionais? Um dos caminhos que se apresenta é desenvolver sistemas flexíveis, i.e. que permitam modificações em seu comportamento durante a interação, oferecendo ao usuário a possibilidade de ajustar a interface de acordo com as suas preferências, necessidades e situações de uso. O design de interfaces flexíveis, que façam sentido e sejam acessíveis a mais pessoas, demanda abordagens que permitam conhecer e formalizar os diferentes requisitos de interação, definir funcionalidades e determinar o comportamento ajustável do sistema. Soluções encontradas na literatura relacionadas ao tema interfaces ajustáveis, (ou tailoring em inglês) enfatizam questões relacionadas à infra-estrutura necessária para o ajuste, não tendo sido encontrados trabalhos que apoiassem os designers de forma prática durante o processo de concepção dessas interfaces. Esta tese propõe e apresenta um framework para o design de interfaces de usuário ajustáveis, denominado PLuRaL. O termo framework é utilizado aqui no seu sentido mais amplo como uma estrutura composta por diretrizes, mecanismos, artefatos e sistemas usados no planejamento e na tomada de decisões de design. O PLuRaL adota uma perspectiva sócio-técnica para a concepção das interfaces ajustáveis e uma visão abrangente dos requisitos de interação, incluindo aqueles que são controversos ou minoritários e advindos não somente de usuários, mas também de diferentes dispositivos e ambientes de interação. Aspectos semânticos, pragmáticos e o impacto social da interação também são considerados. Por fim, o comportamento ajustável do sistema é modelado utilizando-se o conceito de normas. O referencial teórico-metodológico adotado para o trabalho de pesquisa envolveu as disciplinas de Interação Humano-Computador e Semiótica Organizacional. A construção do framework foi pautada por 2 estudos de caso envolvendo populações de usuário heterogêneas em contextos de sistemas de governo eletrônico e de rede social inclusiva. A validação do framework foi realizada com 17 designers e os resultados sugerem uma avaliação positiva considerando a utilidade, flexibilidade para apoiar mudanças, liberdade de criação e satisfação com as propostas de design resultantes / Abstract: The socialization of computer systems has brought a new challenge to Human-Computer Interaction researchers: how to design interfaces that provide access to as many users as possible regardless of their sensory, physical, cognitive and emotional characteristics? One approach to answer this question is to develop flexible systems, i.e. those that allow changes in their behavior during the interaction, offering users the possibility to tailor the interface according to their preferences, needs and situations of use. The design of flexible interfaces, which make sense and are accessible to more people, demands approaches to understand and formalize the different interaction requirements, define functionalities and determine the system tailorable behavior. Solutions found in the literature about tailorable interfaces have focused on the infrastructure needed to offer flexibility and works to support designers in a practical way during the conception of such interfaces were not found. This thesis proposes and presents a framework for the design of tailorable user interfaces, named PLuRaL. The term framework is used here in its broadest sense as a structure consisting of guidelines, mechanisms, artifacts and systems used in design planning and decision-making. PLuRaL adopts a socio-technical approach to design tailorable interfaces and a comprehensive view for interaction requirements, including those that are controversial or from minority, and arising not only from users, but also from different devices and interaction environments. The semantic, pragmatic and social impacts of the interaction are also considered. Finally, the behavior of the tailorable system is modeled using the concept of norms. The theoretical and methodological references adopted in this work involved the disciplines of Human-Computer Interaction and Organizational Semiotics. The framework's construction was guided by 2 case studies with heterogeneous populations, in the context of electronic government and inclusive social network system. The framework's validation was performed with 17 designers and the results suggest a positive evaluation considering the usefulness and flexibility to support changes, freedom to create and satisfaction with the final design proposals / Doutorado / Metodologia e Tecnicas da Computação / Doutor em Ciência da Computação
4

Um estudo sobre o design, a implementação e a avaliação de interfaces flexíveis para idosos em telefones celulares / A research on design, implementation and evaluation of flexible interfaces for the elderly in mobile phones

Vinicius Pereira Gonçalves 16 April 2012 (has links)
A população idosa cresce no Brasil e cada vez mais se faz necessário desenvolver tecnologias de informação e comunicação adequadas a esse público. Com o barateamento dos telefones celulares, muitas famílias gostariam que seus idosos fossem usuários desses dispositivos visando ter contato com os mesmos quando esses estão fora de suas casas. No entanto, o design atual de celulares privilegia o público jovem, não levando em consideração as diferentes necessidades da população idosa. No mais, mesmo na população idosa, há diferenças com relação à escolaridade, experiência com tecnologias, habilidades cognitivas e destreza física. Este trabalho argumenta a favor do design, da implementação e da avaliação de interfaces que sejam flexíveis para atender à diversidade de requisitos dos idosos na interação com celulares. Uma abordagem para o design de interfaces de usuário flexíveis foi aplicada em um experimento exploratório e, considerando-se resultados de uma atividade estudo empírico com usuários idosos, um conjunto de normas que definem o design do comportamento flexível do sistema foi especificado. Esta dissertação propõe e apresenta um framework que propicia a reconfiguração de interfaces em tempo de interação, denominado de FlexInterface. Esse framework aborda o conceito de elementos da interface sendo, componentes que são carregados, instanciados e destruídos quando solicitados. Além disso, esta dissertação apresenta também uma abordagem que apoia a avaliação de interfaces flexíveis para idosos em telefones celulares. A abordagem analítica proposta, apresenta heurísticas específicas para esse contexto de uso. Por fim, uma avaliação com idosos foi realizada para verificar a viabilidade da proposta. Esse estudo constatou que houve uma redução no tempo de interação com o uso da interface flexível e um aumento na satisfação do usuário / The elderly population grows in Brazil and this fact increases the need to develop appropriate information and communication technologies to the public. As cell phones are getting cheaper, many families would like their elderly to be users of these devices aiming to have contact with them when they are out of their homes. However, the current cell phones design favors the younger people, not considering the different needs of the elderly population. At the most, even in the elderly population, there are differences regarding education, experience with technology, cognitive abilities and physical prowess. This dissertation argues for the design, implementation and evaluation of interfaces that are flexible to meet the diverse requirements of the elderly in the interaction with cell phones. One approach to the design of flexible user interfaces was applied in a case study and, considering the results of a practice with elderly users, a set of norms which define the design of the system flexible behavior was specified. This dissertation proposes and presents a framework that provides the interface reconfiguration during the interaction time, named FlexInterface. This framework addresses the concept of interface elements as components that are loaded, instantiated and destroyed when requested. Furthermore, this dissertation also brings an approachthat supports the evaluation of flexible interfaces for the elderly in mobile phones. The proposed analytical approach presents heuristics for this specific context of use. Finally, an assessment with elderly people was performed to verify the feasibility of the proposal. This study found that there was a reduction in the interaction time with the use of flexible interface and an increase in the users satisfaction
5

Computer-Aided Formulation of Magnetic Pastes for Magnetic Components in Power Electronics

Ding, Chao 25 May 2021 (has links)
Magnetic components are necessary for switch-mode power electronics converters, but they are often the bulkiest and heaviest in the system. Novel magnetic designs with intricate structures lead to the size reduction of power electronics converters but pose challenges to the fabrication process and material availability. Because of their low-temperature and pressure-less process-ability, magnetic pastes would be the material of choice to make magnetic cores with complex geometries. However, most magnetic pastes reported in the literature suffer from low relative permeability (µr < 26) due to the low magnetic fraction limited by viscosity. The conventional approach of developing magnetic pastes involves experimental iterations with trial-and-error efforts to determine the optimal compositions. To shorten the development cycle and take advantage of the computational power in the current age, this work focuses on exploring, validating, and demonstrating a computer-aided methodology to correlate material's processing, microstructure, and property to guide the development of magnetic pastes. The discrete element method (DEM) simulation was explored to create materials' microstructure and the finite element method (FEM) simulation was utilized to study the magnetic permeability based on the microstructure created by DEM or taken from an actual material sample. The combination of DEM and FEM provided the linkage among processing-microstructure-property relations. Then, the methodology was verified and demonstrated by improving a starting formulation. The formulation was modeled with DEM based on multiple variables, e.g., particle shape, size, size distribution, mixing ratio, gap, gap distribution, magnetic volume fraction, etc. The optimal mixing ratio of different powders to achieve the maximum magnetic fraction was determined by DEM. Experimental results confirmed the predicted optimal mixing ratio. To further take advantage of the computational tools, the magnetic permeability of the magnetic pastes was computed by FEM based on the DEM-generated microstructures. The effects of powder mixing ratio and magnetic volume fraction on the magnetic permeability were studied, respectively. Compared with the experimental values, the microstructure-based FEM simulations could predict the magnetic permeability of the formulations with varied powder mixing ratios or magnetic volume fractions with an average error of only 10 %. Another critical aspect of employing magnetic pastes for magnetic components in power electronics is capable of tailoring their magnetic permeability to meet different design needs. The methodology was further verified and demonstrated by guiding the selection of composition parameters for tailorable magnetic permeability of a starting formulation with flaky particles. An FEM model was constructed from a microstructural image and varied parameters were explored (particle permeability, matrix permeability, particle volume fraction, etc.) to tailor the magnetic permeability. To verify the simulated results, a set of magnetic pastes with various volume fractions of flakes was prepared experimentally and characterized for their permeability. Comparing the simulated and measured permeability, the error was found to be less than 10 %. Last, the guideline was demonstrated to predict a material composition to achieve a target relative permeability of 30. From the predicted composition, the magnetic paste was prepared and characterized. The error between experimental permeability and the target was only 5 %. With the guideline, one can formulate magnetic pastes with tailorable permeability with minimal experimental effort and select the composition parameters to achieve a target permeability. After developing a series of magnetic pastes with tailorable permeability and a maximum value of 35, the feasibility of making magnetic components with magnetic pastes was demonstrated. The commonly used magnetic cores – C-core, E-core, toroid core, bar core, and plate core were fabricated by a low-temperature (< 200 °C) and pressure-less molding process. Several innovative magnetic components with intricate core structures were also fabricated to demonstrate the shape-forming flexibility. The magnetic paste can also be used as the feedstock for paste-extrusion-based additive manufacturing, which further enhances the shape-forming capability. For demonstration, a multi-permeability core was fabricated by 3D printing the magnetic pastes with tailored permeability. The feasibility of making high-performance magnetic components by additive manufacturing or low-temperature pressure-less molding of magnetic pastes opens the door to power electronics researchers to explore more innovative magnetic designs to further improve the efficiency and power density of the power electronics converters. / Doctor of Philosophy / Magnetic components are necessary for switch-mode power electronics converters, but they are often the bulkiest and heaviest in the system. To reduce the size of the power converters, it is crucial to reduce the size of magnetic components by employing innovative magnetic designs. However, the complicated geometries of the novel magnetic designs pose challenges to the availability of material feedstock and the fabrication process. Magnetic pastes would be the material of choice to make magnetic components with intricate structures because of their flexibility in shape-forming with low-temperature and pressure-less processes. However, most magnetic pastes reported in the literature suffer from low magnetic permeability due to the low magnetic fraction limited by viscosity. The conventional approach of developing magnetic pastes involves experimental trial-and-error efforts to determine the optimal compositions. To shorten the development cycle and take advantage of computational power in the current age, this project focuses on exploring, validating, and demonstrating a computer-aided way to correlate material's processing, microstructure, and property relations to guide material development. The numerical simulations were explored to generate the microstructures and study the properties. With the guidance provided by computer simulations, a series of magnetic pastes with tailorable permeability was developed. Several novel magnetic components were fabricated with the as-developed magnetic pastes via molding or additive manufacturing to demonstrate the shape-forming flexibility.
6

<b>TAILORABLE ENERGETIC MATERIALS: PROPELLANT MANUFACTURING AND MODIFICATION OF EXPLOSIVES’ WAVE SHAPES AND SENSITIVITIES</b>

Joseph Robert Lawrence (18417564) 20 April 2024 (has links)
<p dir="ltr">Tailorable energetics are energetic materials that can be modified to alter their performance and sensitivity. Examples of tailoring energetic materials include additive manufacturing, manufactured hot spots, switchable energetics, and cocrystallization. Developing novel energetic material is a difficult and cost intensive process, because of this, tailoring the performance and sensitivity of existing energetic materials is critical for continued improvement. Additive manufacturing has provided new methods for generating complex geometries of composite materials. Additive manufacturing of composite materials through direct-ink-write (DIW) experiences extrusion limitations due to the high viscosities of highly solids loaded mixtures; the limitations being more severe with smaller syringe tip diameter. A novel printing technique called vibration-assisted printing (VAP) was developed as a method to extend the extrudability limits and extrusion speeds observed with direct-ink-write systems. Printability envelopes were shown in previous work to extend extrudability of monomodal glass bead composites in VAP systems over conventional DIW systems. This study compares the mass flowrates and extrudability limits for bimodal mixtures of glass beads suspended in a hydroxyl-terminated polybutadiene (HTPB) binder for both VAP and DIW printing as a function of volume percent solids loading. The bimodal glass bead mixtures showed a linear response in extrusion rate versus solids loading for both VAP and DIW systems. The VAP system was able to print higher volume loadings than the direct-ink-write system. In addition to extending the extrudability limits, the mass flowrate for the VAP system was significantly higher at all volume loadings tested compared to the DIW. Interestingly, bimodal mixtures were shown to extrude quicker than the monomodal mixtures at all volume loadings and across both printing systems.</p><p><br></p><p dir="ltr">Inhomogeneities within explosives affect the sensitivity and detonation wave shape of energetic materials. The influence of voids on explosive initiation has been well documented; however, the effects that voids between 0.1 mm and 10 mm have on a propagating detonation wave remains largely unexplored. The effect of single cylindrical voids on detonation wave shape and re-initiation was examined here using manufactured voids in a rubberized 1,3,5-trinitro-1,3,5-triazinane (RDX) explosive. Two streak imaging techniques were fielded to investigate void influence. For the first, back-surface streak imaging, the location of the void on the samples was changed and the resulting change in detonation wave shape at the downstream breakout was captured using a streak camera in cut-back experiments. The results from this experiment showed the effects of an initial jet form for short cut-back distances and as shock propagation progressed, the jet formation was absorbed by the unaffected portions of the wave front. The second method, top-surface streak imaging, was used to investigate the re-initiation/downstream propagation of the detonation front and the detonation velocity of the rubberized explosive. These experiments were compared to similar experimental results from machined voids in PBX 9501, a 1,3,5,7-tetranitro-1,3,5,7-tetrazocane (HMX)-based explosive, to investigate the interaction of a detonation wave with a 0.5 mm void for different explosives. The experiments were also compared to simulations using a multi-dimensional and multi-material hydrodynamic code (CTH). These results showed the influence that small features can have on detonation wave shaping and how explosive properties play a key role in that interaction. In addition to air-filled voids, this study examined the effects of 0.5 mm diameter voids filled with different inert metals on the detonation wave shape for an RDX-based rubberized explosive. The metals selected for experiments were 1066 aluminum, brass, copper, and tungsten. Experimental results showed that the extent of detonation wave shaping was closely tied to the density differential between the bulk explosive and metal insert. Simulations were performed using CTH to further analyze material inclusions. Forty-four different filler materials were simulated to isolate the driving factors for wave shaping of the detonation front. The main factors of interest were bulk sound speed, shock impedance, and filler material density. Understanding the influence of material inclusions on detonation performance and wave shape allows for tailoring of detonations as well as characterizing how unintentional defects will alter the explosive.</p><p><br></p><p dir="ltr">Improving the safety of explosive materials through the synthesis of insensitive explosives has been studied extensively. However, little work has focused on creating switchable explosives. A switchable explosive is normally insensitive to detonation, and therefore safe to handle and transport, but can be sensitized when needed to create a functional explosive. Similarly, it may be desired to desensitize an explosive to prevent its function. This study examined the ability to create a switchable RDX-based rubberized explosive using thermally-expandable microspheres (TEMs). The addition of TEMs to the explosive formulation allowed for microstructural changes and potential hot spot locations such as voids to form as the microspheres expanded. Small voids (less than about 10 µm) are more likely to be critical hot spots when shocked, and likewise larger voids are less likely to ignite successfully (sub-critical) when shocked. Consequently, both sensitization and desensitization are possible. The rubberized explosive considered here with unexpanded microspheres was unable to sustain a detonation for the size used, but after specific heating followed by cooling to produce small voids, a detonation was achieved. That is, the TEMs addition to the RDX-based rubberized explosive resulted in an explosive that is detonation insensitive when unheated but becomes a functional explosive after it is sensitized through heating. This paves the way to create insensitive explosive formulations with on-demand switchable detonation function through the incorporation of thermally-expandable microspheres. Desensitization was also demonstrated with specific heating of TEMs in an initially detonable explosive charge. And finally, we also demonstrated that deflagration can be affected by heating TEMs.</p><p><br></p><p dir="ltr">Energetic cocrystallization is a technique that produces a cocrystal that is formed using two known explosives to potentially gain the benefits of one or both without the drawbacks for a particular application. A comparison of cocrystals to a physical mixture of the same coformers can be considered. Cocrystals have unique material properties and crystal structure, whereas a physical mixture is just a mixed combination of the known materials at the same molar ratio. This study used photon Doppler velocimetry (PDV) to compare the particle velocity for 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) and 1-methyl-3,5-dinitro-1,2,4-triazole (MDNT) at a 1:1 molar ratio for both a cocrystal and a physical mixture of the two energetic materials. This cocrystal was previously shown to detonate faster than a physical mixture. However, the PDV results here were not consistent with this result. In addition to measuring output particle velocity with PDV, the cocrystal was characterized to examine phase purity and possible signs of deterioration of the material over time. Evaluating the cocrystal with Fourier-transform infrared spectroscopy (FT-IR), bomb calorimetry, and powder X-ray diffraction (PXRD) allowed for more accurate comparison and greater confidence in the particle velocity measurements obtained in these experiments. The most significant difference in the material characterization results was the difference in enthalpy of formation, as the material tested in this study had a substantially lower enthalpy of formation than previously measured for a CL-20/MDNT cocrystal.</p>
7

MECHANICS OF STRUCTURE GENOME-BASED MULTISCALE DESIGN FOR ADVANCED MATERIALS AND STRUCTURES

Su Tian (14232869) 09 December 2022 (has links)
<p>Composite materials have been invented and used to make all kinds of industrial products, such as automobiles, aircraft, sports equipment etc., for many years. Excellent properties such as high specific stiffness and strength have been recognized and studied for decades, motivating the use of composite materials. However, the design of composite structures still remains a challenge. Existing design tools are not adequate to exploit the full benefits of composites. Many tools are still based on the traditional material selection paradigm created for isotropic homogeneous materials, separated from the shape design. This will lose the coupling effects between composite materials and the geometry and lead to less optimum design of the structure. Hence, due to heterogeneity and anisotropy inherent in composites, it is necessary to model composite parts with appropriate microstructures  instead of simplistically replacing composites as black aluminum and consider materials and geometry at the same time.</p> <p><br></p> <p>This work mainly focuses on the design problems of complex material-structural systems through computational analyses. Complex material-structural systems are structures made of materials that have microstructures smaller than the overall structural dimension but still obeying the continuum assumption, such as fiber reinforced laminates, sandwich structures, and meta-materials, to name a few. This work aims to propose a new design-by-analysis framework based on the mechanics of structure genome (MSG), because of its capability in accurate and efficient predictions of effective properties  for different solid/structural models and three-dimensional local fields (stresses, strains, failure status, etc). The main task is to implement the proposed framework by developing new tools and integrating these tools into a complete design toolkit. The main contribution of this work is a new efficient high-fidelity design-by-analysis framework for complex material-structural systems.</p> <p><br></p> <p>The proposed design framework contains the following components. 1) MSG and its companion code SwiftComp is the theoretical foundation for structural analysis in this design framework. This is used to model the complex details of the composite structures. This approach provides engineers the flexibility to use different multiscale modeling strategies. 2) Structure Gene (SG) builder creates finite element-based model inputs for SwiftComp using design parameters defining the structure. This helps designers deal with realistic and meaningful engineering parameters directly without expert knowledge of finite element analysis. 3) Interface is developed using Python for easy access to needed data such as structural properties and failure status. This is used as the integrator linking all components and/or other tools outside this framework. 4) Design optimization methods and iteration controller are used for conducting the actual design studies such as parametric study, optimization, surrogate modeling, and uncertainty quantification. This is achieved by integrating Dakota into this framework. 5) Structural analysis tool is used for  computing global structural responses. This is used if an integrated MSG-based global analysis process is needed.</p> <p><br></p> <p>Several realistic design problems of composite structures are used to demonstrate the capabilities of the proposed framework. Parameter study of a simple fiber reinforce laminated structure is carried out for investigating the following: comparing with traditional design-by-analysis approaches, whether the new approach can bring new understandings on parameter-response relations and because of new parameterization methods and more accurate analysis results. A realistic helicopter rotor blade is used to demonstrate the optimization capability of this framework. The geometry and material of composite rotor blades are optimized to reach desired structural performance. The rotor blade is also used to show the capability of strength-based design using surrogate models of sectional failure criteria. A thin-walled composite shell structure is used to demonstrate the capability of designing variable stiffness structures by steering in-plane orientations of fibers of the laminate. Finally, the tool is used to study and design auxetic laminated composite materials which have negative Poisson's ratios.</p>

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