Orientador: Ricardo Enrique Medrano / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-04T00:41:03Z (GMT). No. of bitstreams: 1 QuilodranAlarcon_OscarEduardo_D.pdf: 15548788 bytes, checksum: 4505ace06d773524a32cc732adb31371 (MD5) Previous issue date: 2003 / Resumo: Os ferros fundidos cinzentos se classificam conforme sua resistência à tração, mas o ensaio de tração dos corpos de prova é lento e inadequado para ser utilizado no controle da produção. A resistência à compressão entre cunhas, mais fácil e rápida de avaliar, está relacionada com a resistência à tração dos ferros fundidos cinzentos por meio de uma equação linear, permitindo a determinação indireta desta última. O objetivo deste trabalho é retomar a pesquisa das características mecânicas dos ferros fundidos cinzentos, mediante a utilização dos ensaios de tração e compressão entre cunhas. Os resultados conseguiram-se s através da fabricação, ensaio e análise metalográfica e de fratura de materiais das classes NBR FC150 a FC300, não ligados (com diversos teores de fósforo e tratamentos térmicos de recozido) e levemente ligados no estado bruto de fusão (fundidos em condições diversas). O ensaio de compressão entre cunhas aplica-se para verificar a qualidade de mancais de FC200. Discute-se a influência das fases no comportamento mecânico, define-se a curva de compressão entre cunhas, o significado das regiões das curvas de tração e de compressão entre cunhas, e verifica-se a relação entre ambas resistências. Demonstra-se que a curva de compressão entre cunhas pode ser utilizada no controle estatístico de processos. Os ensaios de tração realizados com ciclos de carregamento e descarregamento sucessivos conduzem a curvas de tensão de tração relativa versus deformações recuperáveis e permanentes, utilizáveis na melhoria do projeto mecânico. Propõe-se a aplicação da curva de compressão entre cunhas na avaliação da tenacidade à fratura / Abstract: Grey cast irons are classified based on of their tensile strength, but tensile test is slow to perform and inadequate to be used for online quality control. The wedge srength is easer and faster to perform and it is related with the tensile strength of grey cast irons trhough a linear equation. This equation allows the indirect determination of the tensile strength. The aim of the present work is to address the research of the mechanical characteristics of grey cast irons, by focusing the study on the use of tensile and wedge penetration tests. The results were obtained by casting, tensile and wedge penetration testings, and through metallographic and fracture analysis on NBR- FC150 to FC300 no alloyed (several phosphor levels and annealing heat treatments) and as-cast low alloyed materials (using different casting conditions). The wedge penetration test is used for verifying the quality of structural bearings ofNBR-FC200 cast iron. It is discussed influence of phases on the mechanical behavior. It is defined the meaning of each region of tensile and wedge penetration curves and verified the relationship between tensile and wedge penetration strengths. It is shown that the wedge penetration curve can be used on statistical process control. The loading and unloading tensile test lead to curves of relative tension versus recoverable and permanent deformation which enhance mechanical projets. It is proposed to evaluate the fracture toughness of grey cast irons by the wedge compression curve / Doutorado / Materiais e Processos de Fabricação / Doutor em Engenharia Mecânica

Over the past several years, rapid advances in the field of integrated photonics coupled with nanofabrication capabilities have enabled studies of the interaction of light with the mechanics of a variety of physical structures. Concurrently, mechanical resonators have been extensively studied in the MEMS community due to their high quality factors, and have been implemented in a variety of RF filters and oscillators. The combination of MEMS with integrated optomechanical structures can generate a variety of novel devices that can be used for applications in RF-Photonics, timing and optical switching. While there are several demonstrations of electrostatic devices integrated with optomechanical structures, fewer examples exist in the piezoelectric domain. In particular, photonic integration in a piezoelectric material can benefit from some of the traditional strengths associated with this type of actuation, such as the ability to easily scale to higher frequencies of operation by patterning lateral features, the ability to interface with 50Ω electronics and strong electromechanical coupling. In addition, it enables a platform to produce new architectures for photonic-based electronic frequency reference oscillators that incorporate multiple degrees of freedom. This thesis presents the development of a piezoelectrically-actuated acousto-optic modulator in the aluminum nitride (AlN) material system. The process of implementing this device is carried out in five principal stages. First, light coupling from optical fibers to the AlN thin film is demonstrated with the use of on-chip grating couplers, exhibiting a peak insertion loss of -6.6 dB and a high 1 dB bandwidth of 60 nm for operation in the telecommunications C- and L-bands. This is followed by characterization of photonic whispering gallery mode microdisk and microring resonators with optical quality factors on the order of 104. Next, a robust fabrication method combining optical and electron-beam lithography is developed to produce a fully-integrated device preserving the critical features for acoustic and photonic resonators to be colocalized in the same platform. Acousto-optic modulation is demonstrated with the use of a contour mode resonator which drives displacements in the photonic resonator at 653 MHz, corresponding to the mechanical resonance of the composite structure. The modulator is then implemented in an opto-acoustic oscillator loop, for which an initial phase noise of -72 dBc/Hz at 10 kHz offset from the carrier is recorded with a large contribution from thermal noise at the photodetector. Finally, some possibilities to improve the modulator efficiency and oscillator phase noise are provided along with prospects for future work in this area.

Plutonium is a hazardous radioactive material; the α-particles that are emitted are particularly damaging to health should contamination be inhaled or ingested into the body. During long term storage a number of conditions have been observed which can cause plutonium to corrode, which liberates particles from the surface. It is imperative to understand the processes involved in the corrosion of plutonium during long term storage to predict the likely state that metallic pieces may be found should subsequent handling be required. The growth mechanisms of plutonium hydride beyond the nucleation stage are not well understood. Detailed characterisation of the microstructural features associated with hydride reaction sites is required to develop a mechanistic understanding of the growth stage of hydrogen corrosion. Suitable processes and analysis methods were developed using cerium as an analogous material to δ-plutonium; during this stage, the knowledge of the corrosion of cerium by hydrogen was significantly improved using in situ gas dosing equipment, metallographic preparation, light microscopy, scanning electron microscopy (SEM), ion milling, secondary ion mass spectrometry (SIMS), atomic force microscopy (AFM) and vacuum nanoindentation. SEM and ion milling methods developed on cerium were subsequently used on the analysis on pre-formed and passivated hydride reaction sites on δ-plutonium .In situ exposure of electro-refined plutonium and a Pu 0.3 wt% Ga alloy were investigated without prior exposure to oxygen, revealing the as-formed microstructure of the hydride reaction product to be analysed. Subsequent metallographic preparation was used to confirm findings from the in situ analysis. The highest resolution analysis of the hydride product formed on cerium, delta plutonium and electro-refined plutonium has been obtained to date. Hydride reaction sites formed on cerium and δ-Pu were observed to be oblate, confirming growth anisotropy. A mechanism for the anisotropic growth was proposed where the stress fields introduced into the metal surrounding a lower density hydride play a significant role in further development of a hydride reaction site, causing failure of the surface oxide diffusion barrier surrounding a hydride reaction site.

Les émulsions sont très utilisées dans le domaine des cosmétiques, notamment pour les crèmes et les lotions. En fonction de leur composition, elles présentent diverses propriétés en matière de stabilité, de texture, de microstructure et de macrostructure. Il n’existe pas, à l’heure actuelle, d’étude dans la littérature qui se soit intéressée à l’effet de la composition sur ces différentes propriétés et aux relations qui peuvent exister entre celles-ci, tout en mettant en œuvre une maîtrise de la formulation. Pour répondre à cette double problématique, quatorze émulsions huile-dans-eau ont été formulées, avec un protocole maîtrisé, pour lesquelles les concentrations en phase grasse, en gomme acacia et en xanthane varient. Des solutions de xanthane et de gomme acacia ont également été préparées pour comparer l’effet des gommes en émulsion et en phase aqueuse seule. Les produits ont été ensuite caractérisés, de façon la plus complète et objective possible, pour mettre en évidence l’influence de la composition sur les propriétés de l’émulsion et leurs interactions. De nombreux paramètres ont ainsi été collectés par : analyse sensorielle, des observations microscopiques et des mesures en granulométrie laser, des mesures rhéologiques et mécaniques. On peut en conclure que chacun des paramètres de l’émulsion impacte ses propriétés, avec des différences notables, la teneur en phase grasse étant, globalement, prépondérante. Des relations entre l’ensemble des données ont été mises en évidence et permettent de proposer des hypothèses quant à l’impact de la formulation sur les propriétés tactiles des crèmes cosmétiques. / Emulsions are widely used in cosmetics. Depending on their composition, they exhibit various properties in terms of stability, texture, microstructure and macrostructure. At the present time, there a few to no studies in the literature interested in the effect of the emulsions composition on these different properties and the existing link between these characteristics that are implementing a command of the formulation. To address this dual problem, fourteen oil-in-water emulsions were formulated, with a controlled formulation protocol, for which the concentration of oil phase, acacia gum and xanthan gum evolve. Solutions of xanthan and acacia gums were also prepared to compare the effect of the gums on emulsions to the one on aqueous phase alone. The products were then characterized, in the most complete and objective way possible, to illustrate the influence of the composition on the properties of the emulsions and how these interact. Numerous parameters were collected through : ensory analysis, mcroscopic observations and static light scattering measurements, rhlogical and instrumental texture analyses. t can be concluded that the emulsions are well differentiates and that each of the emulsion parameter impacts its properties with significant differences, the oil phase content being preponderant overall. elationships between the data set were highlighted and suggest hypotheses about the impact of the formulation on the tactile properties of cosmetic creams.

We calculate the stress response, or rheology, of a micro-mechanical model suspension of rigid, Brownian spheroids in a Newtonian fluid in an oscillatory shear flow. The straining and rotation components of a linear flow affects the microstructure, or particle orientation in space and time, and thus, the suspension stress. A statistical description of the microstructure is given by an orientation probability distribution function, which quantifies the likelihood of a particle possessing a particular orientation at an instance in time. The evolution of the microstructure results from the memory of the material, advection from the flow, and rotational Brownian motion. The macroscopic stress response is calculated from ensemble averages of the stresslet weighted by the orientation distribution function. First, we calculate the linear stress response of a dilute suspension of rigid, spheroidal, self-propelled particles under a small-amplitude oscillatory shear deformation using regular perturbation theory. The particle activity leads to a direct contribution to the material stress, via self-propulsion, and an indirect contribution due to correlated tumbling events. The mechanism and strength of self-propulsion and correlation between tumbling events can be determined from the linear stress response of an active suspension. Next, we develop a framework for determining the relaxation moduli of a viscoelastic material through the combination of a memory integral expansion and a multimode-frequency oscillatory shear flow. We analytically determine the first nonlinear relaxation modulus of the model suspension through a comparison of the second normal stress difference from the microstructural stress response, calculated via regular perturbation theory, and a co-rotational memory integral expansion. The stress response of the system is reconstructed for the start-up and cessation of steady simple shear and uniaxial extension. Finally, we numerically calculate the nonlinear viscoelasticity of the model system subject to a large-amplitude oscillatory shear flow. In a sufficiently strong flow with oscillation frequency comparable to the material relaxation rate, secondary overshoots in the stress response occur. We attribute the origin of secondary overshoots to particles undergoing a Jeffery orbit during a (half) cycle of the oscillation, analogous to the case of non-Brownian spheroids in steady shear flow.

Les absorbeurs de chocs en matériaux composites sont capables de dissiper une grande quantité d'énergie, grâce à une compétition de deux mécanismes que sont le délaminage et la fragmentation des plis en compression. Ce second mode de rupture a pour origine le plissement, qui s'initie de façon intrinsèque à l'échelle des fibres. Cette thèse est une contribution à la modélisation multi-échelles de la rupture en compression pour la simulation de structures composites. A cette fin, on propose une stratégie en trois étapes. La première consiste à construire un modèle microscopique capable de représenter la physique du plissement. La difficulté est d'intégrer les influences pertinentes en termes de contrainte ultime et d'énergie absorbée, en particulier l'influence des défauts et du cisaillement. La seconde étape consiste à homogénéiser la réponse de ce micromodèle pour une variété de chargements représentatifs. Un modèle de comportement original et paramétré par les défauts de la microstructure est proposé. Il intègre des lois de comportement déterministes, identifiées par des simulations du micromodèle numérique. Enfin, la troisième étape a pour objet d’intégrer ce comportement basé sur la micromécanique dans un modèle à l'échelle du pli, existant et validé. L'implantation est réalisée dans le cadre d’un code de calcul hybride continu/discret, pour mener des simulations d'échantillons et observer les interactions entre le plissement et les autres modes de dégradation. / Composite shock-absorbing devices can dissipate a large amount of energy, thanks to the combined action of delamination and fragmentation of the plies in compression. The latter failure mode is due to kinking, which naturally arises at the scale of the fibers. This Ph.D. is a contribution to the multiscale modeling of this phenomenon for the simulation of composite structures. Therefore, three-step-strategy is adopted. The first step deals with the design of a microscopic model able to represent the kinematics and kinetics of kinking. The difficulty is to include all relevant parameters in terms of ultimate stress and dissipated energy, particularly defects and shear. The second step deals with the nonlinear homogenization of the micromodel reponse for several load paths. This is done by postulating an original constitutive model with a parametric influence of defects. It includes deterministic constitutive laws which are identified through numerical tests on the microstructure. Finally, the third step deals with the introduction of this micromechanics-based behavior in an existing and validated model at the scale of the plies. It is implemented in the framework of a hybrid continuous/discrete computation code, in order to perform sample-scale simulations and observe interactions between kinking and other failure mechanisms.

Abstract The recent trend in low temperature co-fired ceramic (LTCC) technology is to integrate more elements into multilayer modules. This thesis describes work specifically aimed at developing ferroelectric barium strontium titanate (BST) for integration into such modules. In particular, an objective was the development of a novel, electric field controlled, tunable component to be used at microwave frequencies (2–26 GHz). For the application envisaged, relative permittivity is required to be low (100–1000) and adjustable by a suitable applied electric field, the dissipation factor at room temperature must be low (~0.001) at 2–26 GHz, and most importantly, the sintering temperature must be suited to the LTCC technology (~900 °C) Initial work was focused on sol-gel derived Ba0.7Sr0.3TiO3 powders with boron oxide addition, which were sintered at 900 °C, the dissipation factor was 0.006. The dissipation factor was not low enough for the desired microwave application, and attention turned to powders prepared by the mixed-oxide route. The Ba0.7Sr0.3TiO3 powders, fluxed with the optimum amounts of boron oxide and lithium carbonate, could be sintered at 890 °C to the same density as is achieved with un-fluxed Ba0.7Sr0.3TiO3 sintered at 1360 °C. The dissipation factor for this fluxed powder was acceptably low, although permittivity was too high for the particular objective. Subsequently, research was on BST modified by magnesia, 0.4Ba0.55Sr0.45TiO3-0.6MgO (BSTM). With the optimum fluxing additives, the sintering temperature necessary to achieve a dense BSTM-based ceramic was reduced to 950 °C. The developed microstructure was good, and the relative permittivity and dissipation factor values (221, 0.0012 at 1 kHz) at room temperature indicated good microwave properties. Studies were also undertaken with organic-based tape-casting slurries, laminating procedures and burn-out and sintering schedules. Several kinds of tapes were fabricated and characterized. A test structure for the measurement of dielectric properties at 26 GHz of the optimized BSTM-based ceramic was constructed. The specimen was 50 μm thick layer of BST on an alumina substrate. The relative permittivity and tunability were 130 and >15 % at 4 V μm-1 at room temperature. A tunable phase-shifter was fabricated from the same BSTM-based tape using a novel gravure printing technique, and measurements at 26 GHz showed phase shift from 10 to 35° when the electric field was increased from 1 V μm-1 to 2.5 V μm-1. Some exploratory experiments are described to assess the compatibility of the developed BST-based LTCC with commercial LTCC and some electroceramics.

The use of supplementary cementitious materials (SCMs) in commercial construction have been increasing over the last several decades as climate change and sustainability has been gaining global attention. Incorporation of SCMs into concrete mixtures provides several environmental benefits. Since most SCMs are waste by-products of other industries, their use in concrete reduces waste disposal. Additionally, cements substitution with SCMs reduces the carbon footprint of the construction industry. Cement production generates large amounts of CO2 emissions; the use of SCMs reduces the amount of cement in a concrete mixture thereby reducing emissions from its production. In addition to SCMs, modern concretes typically incorporate a combination of chemical admixtures. Adverse interaction of admixtures with cement, with or without the SCMs, or with each other is one of the most common reasons for early-age concrete issues. Since the possible combinations of admixtures are numerous and there is a variety of cements on the market, testing all possible chemical/mineral/cement admixture combinations is impractical. The aim of this research was to cover a broad base of admixture-related issues, each addressing a specific need of the construction industry. There is currently no explanation for why calcium chloride-based accelerator is not always effective when used with high tricalcium aluminate (C3A) cements. It was determined that increasing C3A or gypsum content alone did not appear to significantly affect acceleration; however, the presence of alkalis reduced the effectiveness of CaCl2 accelerator. When CaCl2-based accelerators are used in concrete, they are typically used in combination with other chemical admixtures, such as water-reducing and retarding admixtures (WRRA) to allow for the use of a low water-cementitious material ratio. In order to avoid premature hardening, CaCl2 accelerator is most often added onsite, rather than at the concrete batching plant. Onsite addition can lead to accidental overdose of accelerator. It was found that increasing dosages of calcium chloride-containing accelerating admixtures in the presence of WRRA has a non-linear effect on the pore size distribution and consequently a non-linear increase on the autogenous shrinkage, which can contribute to early-age concrete cracking. Water-reducing admixtures and superplasticizers are added to concrete to improve workability, which decreases not only with a decrease in water-cementitious material ratio, but also with addition of some SCMs. Silica fume and metakaolin are known to decrease workability; fly ash and slag addition improve it. The effect of SCM combinations on workability is typically assumed to be additive. However, this investigation revealed that combining SCMs does not have an additive effect on workability, measured in terms of apparent yield stress and plastic viscosity; consequently, these parameters cannot be estimated from their respective values. Cement replacement with SCMs affects not only workability, but also heat of hydration, and is commonly used to reduce concrete temperature rise in concrete. Prediction and control of concrete temperature rise due to cement hydration is of great significance for mass concrete structures since large temperature gradients between the surface and the core of the structure can lead to cracking thus reducing durability of the structure. A number of equations have been proposed to predict the heat of hydration of cement and cement/SCM blends. However, these equations do not include metakaolin, which is a relatively new mineral admixture. Based on statistical experimental design, an equation was developed to predict the reduction of total hydration heat at 24, 48 and 72 hours with addition of SCMs compared to a plain ordinary portland cement (OPC)-water mixture. The developed equation allows the evaluation of the contribution of Class F fly ash (FA), blast furnace slag (BFS), silica fume (SF) and metakaolin (MK) as well as their combinations. Since metakaolin has been on the market for only about 10 years, the current knowledge on its effect on hydration products and paste microstructure remains incomplete. The effect of MK on the nature of hydration products was evaluated through x-ray diffraction. Its effect on the microstructure was assessed by measuring porosity with nitrogen adsorption and determining nanoindentation modulus as well as the volume fraction of calcium silicate hydrates (C-S-H) with variable packing densities. No significant effect was observed on the nature of hydration products with MK or BFS addition. However, nitrogen-accessible porosity increased with MK and BFS addition, the increase being larger with BFS. The average indentation modulus for the hydration products decreased with addition of MK and BFS, which corresponded to increasing nitrogen accessible pores. The results of this study indicate that phase quantification by quantitative x-ray diffraction (QXRD) of the hydrated paste may not be sufficient to assess the impact of metakaolin or BFS addition on the hydrating cementitious systems, and a multi-technique approach that provides information not only on the amount of hydration products, but also their morphology is preferable.

Doctor of Philosophy / Department of Grain Science and Industry / Hulya Dogan / Jon M. Faubion / The overall hypothesis underlying this study is that the nature and extent of bran interactions with the gluten protein matrix play a dominant role in both 'in-process' dough and final product quality of whole grain baked goods. Therefore, the purposeful manipulation of those interactions should be able to minimize adverse processing or product characteristics resulting from bran inclusion/presence. The approach we took was to study the effects of bran milled to different particle sizes on dough development during and after dough mixing using fundamental rheology combined with traditional cereal chemistry approaches and x-ray microtomography (XMT). The research outcomes were used to create a better picture of how the bran is effecting the dough development and to suggest strategies that allow for the control of that effect. Study-I focused on characterization of the chemical properties, empirical rheological properties and baking performance of flours and dough with different bran contents from different sources. The development of dough microstructure and the resulting crumb texture in the presence of different bran were studied using XMT. HRW and SW bran additions resulted in higher water absorptions (WA) irrespective of the flour type and bran source. Fine bran caused slightly higher WA followed by coarse and as is bran. Both HRW and SW bran decreased the dough stability of HRW flour, while it improved the stability of SW flour doughs. Macro and microstructure of baked products were significantly affected both bran type and addition level. HRW bran added to HRW flour resulted in 8-23% decrease in loaf volume while SW bran added at the same level caused 3-11% decrease. XMT indicated that bran decreased the total number of air cells significantly. SW flour resulted in harder crumb texture than that of HRW flour breads. Overall, SW bran had less detrimental effects on mixing and baking performance of HRW flour. Study-II focused on specific bran particle size and composition on small and large deformation behavior of strong and weak flour doughs. Small deformation behavior was characterized using frequency and temperature sweep tests, while the large deformation behavior was studied using creep–recovery and uniaxial extensional testing. The results revealed that the rheological behavior of bran-enriched doughs depend on type of base flour, bran type, bran replacement level (0, 5, 10%), and the dough development protocol. Weak flour doughs benefited from inclusion of bran as inherently low peak height and stability of these doughs improved in the presence of bran. Temperature sweeps indicated a slight decrease in Gʹ and G" until around 55-60°C. In the same temperature range, presence of bran increased the moduli of composite four compared to that of the control flours. Creep compliance parameters indicated that both bran source and bran replacement had significant effect on maximum compliance (J[subscript max]) and elastic compliance (J[subscript e]). Finally, the bran type affected uniaxial extensional properties, maximum resistance (R[subscript max]) and elasticity (E), significantly independent from the type of base flour.

Une approche combinant simulation numérique et expérimentation est développée pour modéliser la microfissuration complexe dans des matériaux hétérogènes cimentaires. Le modèle numérique proposé a permis de prévoir précisément en 3D l'initiation et la propagation des microfissures à l'échelle de la microstructure réelle d'un échantillon soumis à un chargement de compression. Ses prévisions ont été validées par une comparaison directe avec le réseau de fissures réel caractérisé par des techniques d'imagerie 3D. Dans une première partie, nous développons et testons les outils de simulation numérique. Plus précisément, la méthode de champ de phase est appliquée pour simuler la microfissuration dans des milieux fortement hétérogènes et ses avantages pour ce type de modélisation sont discutés. Ensuite, une extension de cette méthode est proposée pour tenir compte d'un endommagement interfacial, notamment aux interfaces inclusion/matrice. Dans une deuxième partie, les méthodes expérimentales utilisées et développées au cours de cette thèse sont décrites. Les procédures utilisées pour obtenir l'évolution du réseau de fissures 3D dans les échantillons à l'aide de microtomographie aux rayons X et d'essais mécaniques in-situ sont présentées. Ensuite, les outils de traitement d'image utilisant la corrélation d'images volumiques, pour extraire les fissures des images en niveaux de gris avec une bonne précision, sont détaillés. Dans une troisième partie, les prévisions du modèle numérique sons comparées avec les données expérimentales d'un matériau modèle en billes de polystyrène expansé intégrées dans une matrice de plâtre dans un premier temps, et, dans un second temps, d'un béton léger plus complexe. Plus précisément, nous utilisons les données expérimentales pour identifier les paramètres microscopiques inconnus par une approche inverse, et utilisons les déplacements expérimentaux déterminés par corrélation d'images volumiques pour définir des conditions limites à appliquer sur les bords de sous-domaines dans l'échantillon pour les simulations. Les comparaisons directes de réseaux de microfissures 3D et de leur évolution montrent une très bonne capacité prédictive du modèle numérique / An approach combining numerical simulations and experimental techniques is developed to model complex microcracking in heterogeneous cementitious materials. The proposed numerical model allowed us to predict accurately in 3D the initiation and the propagation of microcracks at the scale of the actual microstructure of a real sample subjected to compression. Its predictions have been validated by a direct comparison with the actual crack network characterized by 3D imaging techniques. In a first part, the numerical simulation tools are developed and tested. More specifically, the phase-field method is applied to microcracking simulations in highly heterogeneous microstructures and its advantages for such simulations are discussed. Then, the technique is extended to account for interfacial cracking, possibly occurring at inclusion/matrix interfaces. In a second part, the experimental methods used and developed in this work are described. The procedures to obtain the evolution of the 3D crack network within the samples by means of X-rays computed microtomography and in-situ mechanical testing are presented. Then, we focus on the developed image processing tools based on digital volume correlation to extract with good accuracy the cracks from the grey level images. In a third part, we compare the predictions of the numerical model with experimental results obtained, first, with a model material made of expanded polystyrene beads embedded in a plaster matrix, and second, to a more complex lightweight concrete. More precisely, we use the experimental data to identify by inverse approaches the local microstructural parameters, and use the experimental displacements measured by digital volume correlation to define boundary conditions to be applied on sub-domains within the sample for the simulations. The obtained direct comparisons of 3D microcrack networks and their evolutions demonstrate the very good predictive capability of the numerical model