Ionomeric polymer transducers exhibit electromechanical coupling capabilities. The transport of charge due to electric stimulus is the primary mechanism of actuation for a class of polymeric active materials known as ionomeric polymer transducers (IPTs). The research presented in this dissertation focuses on modeling the cation transport and cation steady state distribution due to the actuation of an IPT. Ion transport in the IPT depends on the morphology of the hydrated Nafion membrane and the morphology of the metal electrodes. Recent experimental findings show that adding conducting powders at the polymer-conductor interface increases the displacement output. However, it is difficult for a traditional continuum model based on transport theory to include morphology in the model. In this dissertation, a two-dimensional Monte Carlo simulation of ion hopping has been developed to describe ion transport in materials that have fixed and mobile charge similar to the structure of the ionic polymer transducer. In the simulation, cations can hop around in a square lattice. A step voltage is applied between the electrodes of the IPT, causing the thermally-activated hopping between multiwell energy structures. By sampling the ion transition time interval as a random variable, the system evolution is obtained. Conducting powder spheres have been incorporated into the Monte Carlo simulation. Simulation results demonstrate that conducting powders increase the ion conductivity. Successful implementation of parallel computation makes it possible for the simulation to include more powder spheres to find out the saturation percentage of conducting powders for the ion conductivity. To compare simulation results with experimental data, a multiscale model has been developed to increase the scale of Monte Carlo simulation. Both transient responses and steady state responses show good agreement with experimental measurements. / Ph. D.

The accurate and efficient numerical simulation of geophysical flows is of great interest in numerical weather prediction and climate modeling as well as in numerous critical areas and industries, such as agriculture, construction, tourism, transportation, weather-related disaster management, and sustainable energy technologies. Oceanic and atmospheric flows display an enormous range of temporal and spatial scales, from seconds to decades and from centimeters to thousands of kilometers, respectively. Scale interactions, both spatial and temporal, are the dominant feature of all aspects of general circulation models in geophysical fluid dynamics. In this thesis, to decrease the cost for these geophysical flow computations, several types of multiscale methods were systematically developed and tested for a variety of physical settings including barotropic and stratified wind-driven large scale ocean circulation models, decaying and forced two-dimensional turbulence simulations, as well as several benchmark incompressible flow problems in two and three dimensions. The new models proposed here are based on two classes of modern multiscale methods: (i) interpolation based approaches in the context of the multigrid/multiresolution methodologies, and (ii) deconvolution based spatial filtering approaches in the context of large eddy simulation techniques. In the first case, we developed a coarse-grid projection method that uses simple interpolation schemes to go between the two components of the problem, in which the solution algorithms have different levels of complexity. In the second case, the use of approximate deconvolution closure modeling strategies was implemented for large eddy simulations of large-scale turbulent geophysical flows. The numerical assessment of these approaches showed that both the coarse-grid projection and approximate deconvolution methods could represent viable tools for computing more realistic turbulent geophysical flows that provide significant increases in accuracy and computational efficiency over conventional methods. / Ph. D.

Ossos são sólidos não homogêneos com estruturas altamente complexas que requerem uma modelagem multiescala para entender seu comportamento eletromecânico e seus mecanismos de remodelamento. O objetivo deste trabalho é encontrar expressões analíticas para as propriedades elástica, piezoelétrica e dielétrica efetivas de osso cortical modelando-o em duas escalas: microscópica e macroscópica. Utiliza-se o Método de Homogeneização Assintótica (MHA) para calcular as constantes eletromecânicas efetivas deste material. O MHA produz um procedimento em duas escalas que permite obter as propriedades efetivas de um material compósito contendo uma distribuição periódica de furos cilíndricos circulares unidirecionais em uma matriz piezoelétrica linear e transversalmente isotrópica. O material da matriz pertence à classe de simetria cristalina 622. Os furos estão centrados em células de uma matriz periódica de secções transversais quadradas e a periodicidade é a mesma em duas direções perpendiculares. O compósito piezoelétrico está sob cisalhamento antiplano acoplado a um campo elétrico plano. Os problemas locais que surgem da análise em duas escalas usando o MHA são resolvidos por meio de um método da teoria de variáveis complexas, o qual permite expandir as soluções correspondentes em séries de potências de funções elípticas de Weierstrass. Os coeficientes das séries são determinados das soluções de sistemas lineares infinitos de equações algébricas. Truncando estes sistemas infinitos até uma ordem finita de aproximação, obtêm-se fórmulas analíticas para as constantes efetivas elástica, piezoelétrica e dielétrica, que dependem da fração de volume dos furos e de um fator de acoplamento eletromecânico da matriz. Os resultados numéricos obtidos a partir destas fórmulas são comparados com resultados obtidos pelas fórmulas calculadas via método de Mori-Tanaka e apresentam boa concordância. A boa concordância entre todas as curvas obtidas via MHA sugere que a expressão correspondente da primeira aproximação fornece uma fórmula muito simples para calcular o fator de acoplamento efetivo do compósito. Os resultados são úteis na mecânica de osso. / Bones are inhomogeneous solids with highly complex structures that require multiscale modeling to understand its electromechanical behavior and its remodeling mechanisms. The objective of this work is to find analytical expressions for the effective elastic, piezoelectric, and dielectric properties of cortical bone by modeling it on two scales: microscopic and macroscopic. We use Asymptotic Homogenization Method (AHM) to calculate the effective electromechanical constants of this material. The AHM yields a two-scale procedure to obtain the effective properties of a composite material containing a periodic distribution of unidirectional circular cylindrical holes in a linear transversely isotropic piezoelectric matrix. The matrix material belongs to the symmetry crystal class 622. The holes are centered in a periodic array of cells of square cross sections and the periodicity is the same in two perpendicular directions. The piezoelectric composite is under antiplane shear deformation together with in-plane electric field. Local problems that arise from the two-scale analysis using the AHM are solved by means of a complex variable method, which allows us to expand the corresponding solutions in power series of Weierstrass elliptic functions. The coefficients of these series are determined from the solutions of infinite systems of linear algebraic equations. Truncating the infinite systems up to a finite, but otherwise arbitrary, order of approximation, we obtain analytical formulas for effective elastic, piezoelectric, and dielectric properties, which depend on both the volume fraction of the holes and an electromechanical coupling factor of the matrix. Numerical results obtained from these formulas are compared with results obtained by the Mori-Tanaka approach and show good agreement. The good agreement between all curves obtained via AHM suggests that the corresponding expression of first approximation provides a very simple formula to calculate the effective coupling factor of the composite. The results are useful in bone mechanics.

Submitted by Maria Cristina (library@lncc.br) on 2017-08-10T14:46:54Z No. of bitstreams: 1 tese_AlineRocha_2017.pdf: 17879231 bytes, checksum: 4f4051ece6ff4381064ab5338f79624d (MD5) / Approved for entry into archive by Maria Cristina (library@lncc.br) on 2017-08-10T14:47:10Z (GMT) No. of bitstreams: 1 tese_AlineRocha_2017.pdf: 17879231 bytes, checksum: 4f4051ece6ff4381064ab5338f79624d (MD5) / Made available in DSpace on 2017-08-10T14:47:21Z (GMT). No. of bitstreams: 1 tese_AlineRocha_2017.pdf: 17879231 bytes, checksum: 4f4051ece6ff4381064ab5338f79624d (MD5) Previous issue date: 2017-03-20 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / In this work we construct a new multiscale computational model to describe the flow of gases in unconventional reservoirs (shale gas) containing distinct levels of fractures (natural and hydraulic). Such reservoirs exhibit peculiar characteristics that make an accurate description of the physical phenomenon involved a hard task. Among the characteristics we can highlight the low permeability (order of nanodarcys) and the multiple levels of porosity related to the multiple scales involved. In the present work the multiscale modeling of the gas flow is built with the formal homogenization procedure. The geological formation is characterized by four distinct length scales. The finest one, the nanoscopic, is related to the nanopores in the organic matter (kerogen) where gas is adsorbed. In order to accurately describe the gas adsorption in kerogen we pursue in the context of the Thermodynamics of Inhomogeneous Fluids. More precisely, the isotherms that describe the gas adsorption in nanopores are built based on the Density Functional Theory (DFT). The upscaling to the microscale is reached through the homogenization procedure. The window of observation related to this scale is composed of kerogen aggregates and inorganic matter (clay, quartz, calcite). Such phases are separated by the network of interparticle pores exibting characteristic length between 10^{-4} and 10^{-9} meters. The micropores are partially-saturated, filled with a free gas phase in thermodynamic equilibrium with the dissolved gas in the aqueous phase. The model considers immobile water phase with the equation of fickian diffusion of the dissolved gas coupled to the Darcyan flow of the free gas. At the mesoscale the shale matrix (where interparticle pores, kerogen aggregates and inorganic matter are envisioned as an homogenized media) is intertwined by the network of natural fractures exhibiting preferred paths for the flow of gas. The upscaling of this coupled system of partial differential equations gives rise to a macroscopic model of double porosity in the sense of Arbogast and coworkers (ARBOGAST; DOUGLAS JR.; HORNUNG, 1990). Within this context the shale matrix behaves as a microstructural distributed mass source term in the mass balance equation that describes the gas movement in the homogenized network of natural fractures. Finally we establish the coupling between the hydrodynamics in the networks of natural and hydraulic fractures, where single phase gas flow takes place. Such coupling is accomplished by reduced dimension techniques where induced fractures are treated as (n-1), n = 2,3 lower dimensional geological objects. The resulting model is composed of three partial differential nonlinear equations governing the gas hydrodynamics in the shale matrix and networks of natural and hydraulic fractures. In order to decouple the system we proceed within the context proposed by Arbogast (ARBOGAST,1997) which adopts a variable decomposition leading to the numerical solution of independent subsystems. This strategy allows the solution of the system mentioned above to be made in a sequential form avoiding additional iterations between the subsystems. The resultant governing equations are discretized by the finite element method with the introduction of submeshes to threat the gas transport in shale matrix and compute the source term in the pressure equation of the natural fractures network. The discretized model is used to simulate gas production as well as transient well tests. Promising numerical results are obtained which can be used to improve the description of the involved phenomena giving rise to new diagnostic curves to the characterization of unconventional reservoirs. / Neste trabalho propomos um novo modelo computacional multiescala para descrever o transporte de gases em reservatórios não convencionais (shale gas) com distintos níveis de fraturas (naturais e hidráulicas). Tais reservatórios apresentam características bastante peculiares que tornam a descrição acurada dos fenômenos físicos envolvidos uma tarefa árdua. Dentre estas características podemos ressaltar a baixíssima permeabilidade (da ordem de nanodarcys) e os múltiplos níveis de porosidade associados às múltiplas escalas envolvidas. No presente trabalho a modelagem multiescala do transporte do gás metano é construída fazendo uso do processo formal de homogeneização. O modelo considera o reservatório descrito por quatro escalas espaciais distintas. A escala mais fina, nanoscópica, é associada aos nanoporos na matéria orgânica (querogênio) onde o gás encontra-se adsorvido. Para descrever precisamente a adsorção do gás no querogênio fazemos uso da Termodinâmica de Gases Confinados. Mais precisamente, as isotermas de adsorção do gás nos nanoporos são construídas fazendo uso da Density Functional Theory (DFT). Através do processo de homogeneização é realizado o upscaling para a escala intermediária (microscópica). A janela observacional associada a esta escala consiste dos agregados de querogênio juntamente com a matéria inorgânica (considerada impermeável) e rede de microporos que podem exibir tamanhos entre 10^{-4} a 10^{-9} metros. Consideramos estes, por sua vez, parcialmente saturados preenchidos por uma fase gás livre em equilíbrio termodinâmico local com o gás dissolvido na fase aquosa. O modelo considera a água estagnada com a equação de difusão fickiana do gás dissolvido acoplada ao escoamento do gás livre. Na mesoescala a matriz do folhelho (na qual microporos, agregados de querogênio e matéria inorgânica são tratados como um meio contínuo homogeneizado) é permeada por uma rede de fraturas naturais que exibem caminhos preferenciais para o movimento do gás. O processo do upscaling deste sistema acoplado de equações diferenciais parciais dá origem a um modelo macroscópico de porosidade dupla no sentido de Arbogast e colaboradores (ARBOGAST; DOUGLAS JR.; HORNUNG, 1990). Neste contexto, a matriz atua como uma fonte de massa distribuída microestruturalmente no balanço de massa que descreve o movimento do gás na rede de fraturas naturais. Finalmente estabelecemos o acoplamento entre as hidrodinâmicas nas redes de fraturas naturais e hidráulicas, onde ocorre o escoamento monofásico do gás livre. Tal acoplamento é realizado via técnica de redução de dimensão onde as fraturas hidráulicas são tratadas como objetos geológicos de dimensão reduzida (n-1), n=2,3. O modelo resultante é composto por três equações diferenciais parciais não lineares acopladas que governam a hidrodinâmica do gás na matriz e redes de fraturas naturais e hidráulicas. Com o intuito de desacoplar o sistema procedemos no contexto proposto por Arbogast (ARBOGAST,1997) que consiste em utilizar uma decomposição das variáveis resultando em subsistemas independentes a serem resolvidos numericamente. Esta escolha permite que o sistema supracitado seja resolvido de forma sequencial evitando a necessidade de iterações adicionais entre os subsistemas. Na discretização espacial adotamos o método de elementos finitos com a introdução de submalhas para tratar o transporte do gás na matriz e assim efetuar de forma precisa o cálculo do termo de fonte na equação da pressão do gás na rede de fraturas naturais. O modelo discreto é utilizado para o cômputo da produção de gás bem como para simular testes transientes de pressão em poços. Resultados numéricos promissores são obtidos os quais podem ser empregados para aprimorar a descrição dos fenômenos envolvidos e dar origem a novas curvas de diagnóstico para caracterização de propriedades de reservatórios não convencionais.

<div>Computational Chemistry has proven to be an effective means of solving chemical problems. The two main tools of Computational Chemistry - quantum mechanics and molecular mechanics, have provided viable avenues to probe such chemical problems at an electronic or molecular level, with varying levels of accuracy and speed. In this work, attempts have been made to combine the speed of molecular mechanics and the accuracy of quantum mechanics to work across multiples scales of time and length, effectively resulting in simulations of large chemical systems without compromising the accuracy.</div><div><br></div><div>The primary tool utilized for methods development and application in this work is the Effective Fragment Potential (EFP) method. The EFP method is a computational technique for studying non-covalent interactions in complex systems. EFP is an accurate \textit{ab initio} force field, with accuracy comparable to many Density Functional Theory (DFT) methods, at significantly lower computational cost. EFP decomposes intermolecular interactions into contributions from four terms: electrostatics, polarization, exchange-repulsion and dispersion.</div><div><br></div><div>In the first chapter, the possibility of applying EFP method to study large radical-water clusters is probed. An approximate theoretical model in which the transition dipole moments of excitations are computed using the information from the ground state orbitals is implemented.</div><div><br></div><div>A major challenge to broaden the scope of EFP is to overcome its limitation in describing only small and rigid molecules such as water, acetone, etc. In the second chapter, the extension of EFP method to large covalently bound biomolecules and polymers such as proteins, lipids etc., is described. Using this new method, referred to as BioEFP/mEFP, it is shown that the effect of polarization is non-negligible and must be accounted for when modeling photochemical and electron-transfer processes in photoactive proteins.</div><div><br></div><div>Another area of interest is the development of novel drug-target binding models, in which a chemically active part of the ligand is modified via functional group modification, while the rest of the system remains intact. In the third chapter, the development and application of a drug-target binding model is explained.<br></div><div><br></div><div><div>Lastly, in the fourth and final chapter, we show the derivation for working equations corresponding to the coupling gradient term describing the dispersion interactions between quantum mechanical and effective fragment potential regions.</div><div><br></div><div>The primary focus of this work is to explore and expand the boundaries of multiscale QM/MM simulations applied to chemical and biomolecular systems. We believe that the work described here leads to exciting pathways in the future in terms of modeling novel systems and processes such as heterogeneous catalysis, QSAR, crystal structure prediction, etc.</div></div>

First-principles calculations such as density functional theory (DFT) employ numerical approaches to solve the Schrodinger equation of a system. Standard functionals employed to determine the cohesive system energy, specifically the local density and generalized gradient approximations (LDA and GGA), underestimate the correlation of 5f electrons to their ions in AO₂ systems (A=U/Pu/Np). The standard correction, the "Hubbard +U," causes the multidimensional energy surface to develop a large number of local minima which do not correspond to the ground state (global minimum). Because all useful energy values derived from DFT calculations depend on small differences between relatively large cohesive energies, comparing systems wherein one or more of the samples are not in the ground state has the potential to introduce large errors. This work presents an analysis of the fundamental issues of metastable states in both pure and binary AO₂ systems, investigates novel methods of handling them, and describes why current literature approaches which appear to work well for the pure compounds are not well-suited for systems containing multiple actinide species.

Diffusive mass transport within porous SOFC components is explored using two modeling approaches that can better inform the SOFC electrode design process. These approaches include performance metrics for electrode cross-sectional design and a fractal approach for modeling mass transport within the pore structure of the electrode reaction zone. The performance metrics presented are based on existing analytical models for transport within SOFC electrodes. These metrics include a correction factor for button-cell partial pressure predictions and two forms of dimensionless reactant depletion current density. The performance impacts of multi-dimensional transport phenomena are addressed through the development of design maps that capture the trade-offs inherent in the reduction of mass transport losses within SOFC electrode cross-sections. As a complement to these bulk electrode models, a fractal model is presented for modeling diffusion within the electrochemically active region of an SOFC electrode. The porous electrode is separated into bulk and reaction zone regions, with the bulk electrode modeled in one-dimension based on the dusty-gas formalism. The reaction zone is modeled in detail with a two-dimensional finite element model using a regular Koch pore cross-section as a fractal template for the pore structure. Drawing on concepts from the analysis of porous catalysts, this model leads to a straightforward means of assessing the performance impacts of reaction zone microstructure. Together, the modeling approaches presented provide key insights into the impacts of bulk and microstructural geometry on the performance of porous SOFC components.

À Paris environ 44% des bâtiments ont été construits avant 1914 avec des murs épais non isolés et des matériaux poreux, caractérisés par une forte inertie thermique et des propriétés hygroscopiques. Les propriétés hygrothermiques des matériaux utilisés dans les constructions anciennes ont des effets qui : (i) confèrent (aux bâtiments) de bonnes qualités thermiques en période estivale et (ii) contribuent à réguler la température et l’humidité relative intérieure. En France les politiques d’économie d’énergie et la régulation thermique ont abouti à la mise en place de l’isolation thermique afin de réduire les consommations d'énergie pendant l'hiver. L'installation de l'isolation thermique dans la rénovation des bâtiments existants pose cependant des difficultés. D’autre part, il est prévu que des conditions extrêmes de chaleur deviennent plus fréquentes dans des scénarios du climat futur. Ainsi, les évolutions possibles du climat futur doivent être intégrées dans l'évaluation des stratégies de rénovation dans le bâtiment ancien. Ce travail de thèse porte sur l'évaluation du comportement hygrothermique de constructions anciennes rénovées à Paris, dans des conditions météorologiques actuelles et de vague de chaleur. A l’échelle des logements un modèle a été construit sur un outil de simulation thermique dynamique, calé et validé à travers des données enregistrées dans une campagne de mesure lancée en 2014 dans les logements étudiés. À l’échelle de la paroi un modèle macroscopique en 2D est proposé afin d'étudier les transferts de chaleur et de masse dans un mur poreux constitué de plusieurs couches avec de l’isolation thermique par intérieur et par l’extérieur. / In Paris 44% of the dwellings were built before 1914 with uninsulated thick walls made of porous materials, characterized by high thermal inertia and hygroscopic properties. The hygrothermal properties of existing buildings materials have effects that: (i) give (to these buildings) good thermal qualities in summer and (ii) help to regulate indoor temperature and relative humidity. In France the energy saving policies and thermal regulation have resulted in the implementation of thermal regulation to reduce energy consumption during winter. Though the installation of thermal insulation in existing buildings poses a number of difficulties. Moreover, it is expected that extreme heat conditions become more frequent in future climate scenarios. Thus, the possible evolutions of future climate must be integrated into the evaluation of renovation strategies in old buildings. This thesis focuses on the assessment of the hygrothermal behavior of old renovated Parisian buildings, in current and heat wave weather. At the building scale (housing), a model was built in dynamic thermal simulation tool. The model was calibrated and validated through recorded data from a measurement campaign launched in 2014 on the studied housings. At the wall scale, a macroscopic model in 2D is proposed to study the heat and mass transfer through a multilayered porous wall, renovated with internal thermal insulation and external thermal insulation.

Ossos são sólidos não homogêneos com estruturas altamente complexas que requerem uma modelagem multiescala para entender seu comportamento eletromecânico e seus mecanismos de remodelamento. O objetivo deste trabalho é encontrar expressões analíticas para as propriedades elástica, piezoelétrica e dielétrica efetivas de osso cortical modelando-o em duas escalas: microscópica e macroscópica. Utiliza-se o Método de Homogeneização Assintótica (MHA) para calcular as constantes eletromecânicas efetivas deste material. O MHA produz um procedimento em duas escalas que permite obter as propriedades efetivas de um material compósito contendo uma distribuição periódica de furos cilíndricos circulares unidirecionais em uma matriz piezoelétrica linear e transversalmente isotrópica. O material da matriz pertence à classe de simetria cristalina 622. Os furos estão centrados em células de uma matriz periódica de secções transversais quadradas e a periodicidade é a mesma em duas direções perpendiculares. O compósito piezoelétrico está sob cisalhamento antiplano acoplado a um campo elétrico plano. Os problemas locais que surgem da análise em duas escalas usando o MHA são resolvidos por meio de um método da teoria de variáveis complexas, o qual permite expandir as soluções correspondentes em séries de potências de funções elípticas de Weierstrass. Os coeficientes das séries são determinados das soluções de sistemas lineares infinitos de equações algébricas. Truncando estes sistemas infinitos até uma ordem finita de aproximação, obtêm-se fórmulas analíticas para as constantes efetivas elástica, piezoelétrica e dielétrica, que dependem da fração de volume dos furos e de um fator de acoplamento eletromecânico da matriz. Os resultados numéricos obtidos a partir destas fórmulas são comparados com resultados obtidos pelas fórmulas calculadas via método de Mori-Tanaka e apresentam boa concordância. A boa concordância entre todas as curvas obtidas via MHA sugere que a expressão correspondente da primeira aproximação fornece uma fórmula muito simples para calcular o fator de acoplamento efetivo do compósito. Os resultados são úteis na mecânica de osso. / Bones are inhomogeneous solids with highly complex structures that require multiscale modeling to understand its electromechanical behavior and its remodeling mechanisms. The objective of this work is to find analytical expressions for the effective elastic, piezoelectric, and dielectric properties of cortical bone by modeling it on two scales: microscopic and macroscopic. We use Asymptotic Homogenization Method (AHM) to calculate the effective electromechanical constants of this material. The AHM yields a two-scale procedure to obtain the effective properties of a composite material containing a periodic distribution of unidirectional circular cylindrical holes in a linear transversely isotropic piezoelectric matrix. The matrix material belongs to the symmetry crystal class 622. The holes are centered in a periodic array of cells of square cross sections and the periodicity is the same in two perpendicular directions. The piezoelectric composite is under antiplane shear deformation together with in-plane electric field. Local problems that arise from the two-scale analysis using the AHM are solved by means of a complex variable method, which allows us to expand the corresponding solutions in power series of Weierstrass elliptic functions. The coefficients of these series are determined from the solutions of infinite systems of linear algebraic equations. Truncating the infinite systems up to a finite, but otherwise arbitrary, order of approximation, we obtain analytical formulas for effective elastic, piezoelectric, and dielectric properties, which depend on both the volume fraction of the holes and an electromechanical coupling factor of the matrix. Numerical results obtained from these formulas are compared with results obtained by the Mori-Tanaka approach and show good agreement. The good agreement between all curves obtained via AHM suggests that the corresponding expression of first approximation provides a very simple formula to calculate the effective coupling factor of the composite. The results are useful in bone mechanics.

<div>Textile composites have been widely used due to the excellent mechanical performance and lower manufacturing costs, but the accurate prediction of the mechanical behaviors of textile composites is still very challenging due to the complexity of the microstructures and boundary conditions. Moreover, there is an unprecedented amount of design options of different textile composites. Therefore, a highly efficient yet accurate approach, which can predict the macroscopic structural performance considering different geometries and materials at subscales, is urgently needed for the structural design using textile composites.</div><div><br></div><div>Mechanics of structure genome (MSG) is used to perform multiscale modeling to predict various performances of textile composite materials and structures. A two-step approach is proposed based on the MSG solid model to compute the elastic properties of different two-dimensional (2D) and three-dimensional (3D) woven composites. The first step computes the effective properties of yarns at the microscale based on the fiber and matric properties. The effective properties of yarns and matrix are then used at the mesoscale to compute the properties of woven composites in the second step. The MSG plate and beam models are applied to thin and slender textile composites, which predict both the structural responses and local stress field. In addition, the MSG theory is extended to consider the pointwise temperature loads by modifying the variational statement of the Helmholtz free energy. Instead of using coefficients of thermal expansions (CTEs), the plate and beam thermal stress resultants derived from the MSG plate and beam models are used to capture the thermal-induced behaviors in thin and slender textile composite structures. Moreover, the MSG theory is developed to consider the viscoelastic behaviors of textile composites based on the quasi-elastic approach. Furthermore, a meso-micro scale coupled model is proposed to study the initial failure of textile composites based on the MSG models which avoids assuming a specific failure criterion for yarns. The MSG plate model uses plate stress resultants to describe the initial failure strength that can capture the stress gradient along the thickness in the thin-ply textile composites. The above developments of MSG theory are validated using high-fidelity 3D finite element analysis (FEA) or experimental data. The results show that MSG achieves the same accuracy of 3D FEA with a significantly improved efficiency.</div><div> </div><div>Taking advantage of the advanced machine learning model, a new yarn failure criterion is constructed based on a deep neural network (DNN) model. A series of microscale failure analysis based on the MSG solid model is performed to provide the training data for the DNN model. The DNN-based failure criterion as well as other traditional failure criteria are used in the mesoscale initial failure analysis of a plain woven composite. The results show that the DNN yarn failure criterion gives a better accuracy than the traditional failure criteria. In addition, the trained model can be used to perform other computational expensive simulations such as predicting the failure envelopes and the progressive failure analysis.</div><div> </div><div>Multiple software packages (i.e., texgen4sc and MSC.Patran/Nastran-SwiftComp GUI) are developed to incorporate the above developments of the MSG models. These software tools can be freely access and download through cdmHUB.org, which provide practical tools to facilitate the design and analysis of textile composite materials and structures.</div>