Search

Polycrystalline materials have shown promise in advanced optical applications becauseof their unique optical and mechanical properties. As transparent polycrystalline materials become more important in optical applications, evaluation of their transmission across a wide range of wavelengths is crucial to device design. Most polycrystalline materials have non-uniform optical properties due to residual porosity, secondary phases, and/or crystalline anisotropies (e.g. birefringence). To better understand and describe transmission in these materials, an in-line transmission model is developed that incorporates reflection, scattering, and absorption losses. The model was fit onto transmission data from three polycrystalline material systems: ruby, yttria stabilized zirconia, and terbia. Parameters extracted from these fits can be used to describe wavelength dependent transmission with one simple analytical expression. The fit can also be used to decouple absorption form scattering, allowing for the extraction of important properties such as absorption coefficients. Another unique challenge to modeling transmission by transparent ceramics is modeling the scattering losses from birefringence. Even in the case of a single-phase polycrystal with negligible porosity, birefringence scattering will always be present whenever the crystal is anisotropic (non-cubic). Multiple models for birefringence scattering have been suggested in the literature that are generally successful in describing scattering loss in specific material systems. However, these models do not readily extrapolate to new material systems and their connection to birefringence scattering are never fully justified. We remedy this by deriving from Maxwell’s microscopic equations a first-principles model of birefringent scattering that is applicable to any single-phase, unaligned transparent polycrystal. This is achieved by first developing a framework for describing light propagation in dielectric solids by pertur

Many types of bio-inspired appendages have been designed for locomotion on various terrains. In this paper, a novel Jagged Anisotropic Mechanically Jamming (JAMJam) Appendage is presented which is passively compliant and super-underactuated, needing only one actuator to power multiple appendages. The JAMJam's characteristics are studied, with 'straight' appendages generating less force than 'curved' appendages, but requiring smaller sweep angle. A robot utilizing the appendages is designed for shallow-water environments, which can both walk while semi-submerged at up to 9 cm/s and swim at 7.2 cm/s. The robot is capable of locomotion in both turf and sandy laboratory conditions, and can traverse over obstacles in its path.

An equivalent single layer approach to model fracture events of multidirectional balanced thin-ply laminates via the use of the Phase Field method is explored. The inherent anisotropic nature of a multidirectional laminate is taken into account through the use of a structural tensor, defined from scaled directional vectors, which can account for the variation in fracture toughness of the laminates in varying directions. The scaling constants are defined using the lay-up of the laminate and the intra-laminar fracture toughness of the lamina, minimizing the number of input parameters required while also alleviating the structural tensor of a pure numerical and geometric meaning. They have a significant effect in the solution, and are here related to materials properties, not only providing a new perspective on their definition but also allowing the reduction of the number of numerical parameters used to calibrate the anisotropic PF model. The numerical implementation of the proposed formulation is performed using a simple and robust thermal analogy in Abaqus by exploiting the use of an anisotropic conductivity matrix that plays the role of the structural tensor in the anisotropic phase field formulation, which reduces the complexity of the simulations. Experimental results, based on open-hole tension and double edge-notched tension, are reproduced via simulation validating the model for size effects and for the response to off-axis loading. Successful prediction of notch size effects in multidirectional composite laminates is achieved by means of an equivalent single layer approach, incl. the off-axis open-hole tension strengths of a directional thin-ply laminate. All numerical strength predictions were well within acceptable errors of the respective experimental values.

An equivalent single layer approach to model fracture events of multidirectional balanced thin-ply laminates via the use of the Phase Field method is explored. The inherent anisotropic nature of a multidirectional laminate is taken into account through the use of a structural tensor, defined from scaled directional vectors, which can account for the variation in fracture toughness of the laminates in varying directions. The scaling constants are defined using the lay-up of the laminate and the intra-laminar fracture toughness of the lamina, minimizing the number of input parameters required while also alleviating the structural tensor of a pure numerical and geometric meaning. They have a significant effect in the solution, and are here related to materials properties, not only providing a new perspective on their definition but also allowing the reduction of the number of numerical parameters used to calibrate the anisotropic PF model. The numerical implementation of the proposed formulation is performed using a simple and robust thermal analogy in Abaqus by exploiting the use of an anisotropic conductivity matrix that plays the role of the structural tensor in the anisotropic phase field formulation, which reduces the complexity of the simulations. Experimental results, based on open-hole tension and double edge-notched tension, are reproduced via simulation validating the model for size effects and for the response to off-axis loading. Successful prediction of notch size effects in multidirectional composite laminates is achieved by means of an equivalent single layer approach, incl. the off-axis open-hole tension strengths of a directional thin-ply laminate. All numerical strength predictions were well within acceptable errors of the respective experimental values.

An equivalent single layer approach to model fracture events of multidirectional balanced thin-ply laminates via the use of the Phase Field method is explored. The inherent anisotropic nature of a multidirectional laminate is taken into account through the use of a structural tensor, defined from scaled directional vectors, which can account for the variation in fracture toughness of the laminates in varying directions. The scaling constants are defined using the lay-up of the laminate and the intra-laminar fracture toughness of the lamina, minimizing the number of input parameters required while also alleviating the structural tensor of a pure numerical and geometric meaning. They have a significant effect in the solution, and are here related to materials properties, not only providing a new perspective on their definition but also allowing the reduction of the number of numerical parameters used to calibrate the anisotropic PF model. The numerical implementation of the proposed formulation is performed using a simple and robust thermal analogy in Abaqus by exploiting the use of an anisotropic conductivity matrix that plays the role of the structural tensor in the anisotropic phase field formulation, which reduces the complexity of the simulations. Experimental results, based on open-hole tension and double edge-notched tension, are reproduced via simulation validating the model for size effects and for the response to off-axis loading. Successful prediction of notch size effects in multidirectional composite laminates is achieved by means of an equivalent single layer approach, incl. the off-axis open-hole tension strengths of a directional thin-ply laminate. All numerical strength predictions were well within acceptable errors of the respective experimental values.

It is widely recognized in engineering fracture mechanics that integral and differential forms of nonlocal damage models with a constant internal length scale suffer from an incorrect representation of failure mechanisms either by spurious damage growth or by incorrect damage initiation and propagation. In this regard, in this thesis, a displacement-based gradient-enhanced damage model (GEDM) with a transient internal length scale is formulated and used for failure analysis of quasi-brittle materials. Research is focused on mode-I and mode-II failure mechanisms. In a GEDM, a local field is enhanced into a nonlocal field and the nonlocal field is the output of the enhancement. Displacement-based GEDM enhances local displacement fields into nonlocal displacement fields instead of enhancing local equivalent strain fields into nonlocal equivalent strain fields, as in strain- and stressbased GEDMs. The key ingredient of the proposed extension is a transient internal length scale that tends to zero as the damage parameter tends to one. Various expressions for this transient internal length scale are proposed, formulated, and discussed. Also, the need for correction on the gradient activity operator in mode-II failure is demonstrated. To this end, an anisotropic formulation of the displacementbased GEDM is formulated and used to control the material failure mechanism in mode-II failure. Examples of the new model regularization capabilities are compared to the original/classical displacement-based GEDM with a constant internal length scale. Despite the existence of spurious damage growth in mode-I failure for two dimensional problems (4-point bending beam example) for both the transient isotropic and the transient anisotropic versions, spurious damage growth is eliminated for mode-I failure in one-dimensional problems. Also, the proposed transient isotropic model eliminates spurious damage growth for mode-II failure in two-dimensional problems. However, the damage m, Applied Mechanics

A versatile class of composite materials composed of functional filler particles in polymer matrices are increasingly used in high-performance applications that leverage their adaptable mechanical, electrical, thermal, and other functional properties. The choice of constituent materials largely determines these properties: for example, long fibers redistribute stress efficiently, highly conductive filler particles impart their conductivity to the material, and combinations of ionic and electrically conductive fillers with energy storage materials increase the capacity of battery electrodes. The performance of these composites, however, is highly dependent on the internal arrangement of particles. Consequently, controlling this internal structure enables property improvements and novel functionalities. In particular, combining microstructure control with the design freedom of 3D printing presents opportunities to maximize the performance of functional components by spatially modulating properties and their directionality (e.g. reinforcing high-stress regions, prescribing electrical interconnects, or directing heat away from hot spots), as well as introducing novel combinations of properties.To develop this structural control in printed materials, this work utilizes pressure fields to assemble filler particles into patterns within composites during 3D printing. Particle patterns are engineered to improve material properties by leveraging microscopic acoustic forces on particles, tailoring the particle arrangement for improvements in the functionality of the material. This acoustic patterning technique is integrated into 3D printing with attention to processing constraints (e.g. component and feature sizes, material properties, cost, throughput rate, etc.) required in existing and emerging technological applications. In particular, 3D printed composites with high electrical or thermal conductivity, which are simultaneously mechanically flexible or strain-tolerant, are

A method for the calculation of the acoustic performance of open-cell foammaterials is discussed. From a known micro-structural geometry and theconstituent material, the relevant acoustic properties are computed using apreviously published analytical method for the calculation of the dynamicdrag impedance and a previously published method for the calculation of theelastic moduli. These have been combined and are here used to generate thenecessary inputs to a fully anisotropic state space formulation of a TransferMatrix Method (TMM) based solution where only geometry and materialproperties need to be known. From the TMM solution, the sound absorptionand sound transmission loss of multilayer panels including anisotropic opencell materials is estimated. It is shown that the proposed method may beused in an optimization of sound absorption in multi-layer porous materials, where the different layers can have different degrees of anisotropy in theiracoustic and elastic properties. In the current work, the micro-geometry is based on the Kelvin cellwhich then is modified to achieve a controlled degree of anisotropy. The method has been validated by comparing the absorption and sound transmission loss for isotropic porous materials have been compared to equivalent structures computed with a commercial TMM mode, including a porous material which has been fully characterized with regard to previously published Johnson-Champoux-Allard parameters. In addition the calculated dynamic drag impedance has been compared to measurements conductedon a series of small samples with a defined 3D printed micro geometry forwhich the static flow resistivity has been measured. The method in general underestimates the dynamic drag impedance compared to the static flowresistivity due to not including the contributions to the losses from the constrictions between the struts close to the cell vertices. All verification showa good degree of agreement, confirming that for open-cell porous materials, En metod för beräkning av de akustiska egenskaperna hos skummaterialmed öppna celler diskuteras. Baserat på en känd mikrogeometri and de ingående materialen kan de relevanta akustiska egenskaperna beräknas. Metoden bygger på arbeten för dynamiskt flödesmotstånd och beräkning avelastiska egenskaper som publicerats tidigare. De egenskaperna ¨ar inkluderade i en fullt anisotrop formulering för lösning av en state space TransferMatrix Method (TMM) beräkning, där endast geometri och material krävs som indata. Från TMM-beräkningen kan ljudabsorption och ljudtransmission i konstruktioner med flera skikt uppskattas. Möjligheten att göra optimering av ljudabsorption av flera kombinerade skikt med olika grader avanisotropi i beräknade akustiska och styvhetsegenskaper har visats. I detta arbete baseras mikrogeometrin på en Kelvincell-geometri, som modifierats för att uppnå en definerad grad av anisotropi. Metoden har validerats genom att jämföra absorption och ljudtransmission av ekvivalenta strukturer beräknade med ett kommersiellt TMM-program på ett skum-material som karaktäriserats med avseende på publicerade Johnson-Champoux-Allard parametrar. Dessutom har de beräknade dynamiska flödesmotstånden jämförts medmätningar av statiskt flödesmotstånd på små prov tillverkade med 3D-printer. Metoden underskattar generellt flödesmotståndet jämfört med det uppmätta statiska flödesmotståndet eftersom inverkan av trånga sektioner mellan mikro-strävorna negligeras. All verifiering visar en god nivå av överensstämmelse och bekräftar att metoden skulle kunna användas för att göra nya typer av akustiska konstruktioner i flera lager med porösa material med öppna celler och relativt hög porositet ., QC 220905, VinnExcellence Center for ECO2 Vehicle design, VinnExcellence Center for ECO2 Vehicle design

Anisotropic elasticity and inelasticity is of relevance in many practical applications. The Eulerian formulation for anisotropic elastic and inelastic response based on microstructural vectors is used here to model an injection-moulded low-density polyethylene. In contrast with Lagrangian models of inelasticity, the Eulerian formulation is insensitive to arbitrariness of the reference and intermediate configurations as well as to measures of total and inelastic deformations. A specific strain-space-type anisotropic yield function is proposed that depends on anisotropic measures of elastic deformation and anisotropic hardening variables. Use is also made of a rate-independent model with a smooth elastic-inelastic transition. The material parameters were calibrated to reproduce uniaxial test data for loading in three directions in the moulding plane. In addition, a strongly objective numerical implementation is presented and used to simulate stretching of a plate with a circular hole. In contrast with metals, this polyethylene experiences elastic deformations of about 10%. Although the inelastic spin rate could not be determined by the available test data, simulations of loadings in different material directions yield observable influences of inelastic spin rate.

Anisotropic elasticity and inelasticity is of relevance in many practical applications. The Eulerian formulation for anisotropic elastic and inelastic response based on microstructural vectors is used here to model an injection-moulded low-density polyethylene. In contrast with Lagrangian models of inelasticity, the Eulerian formulation is insensitive to arbitrariness of the reference and intermediate configurations as well as to measures of total and inelastic deformations. A specific strain-space-type anisotropic yield function is proposed that depends on anisotropic measures of elastic deformation and anisotropic hardening variables. Use is also made of a rate-independent model with a smooth elastic-inelastic transition. The material parameters were calibrated to reproduce uniaxial test data for loading in three directions in the moulding plane. In addition, a strongly objective numerical implementation is presented and used to simulate stretching of a plate with a circular hole. In contrast with metals, this polyethylene experiences elastic deformations of about 10%. Although the inelastic spin rate could not be determined by the available test data, simulations of loadings in different material directions yield observable influences of inelastic spin rate.

A versatile class of composite materials composed of functional filler particles in polymer matrices are increasingly used in high-performance applications that leverage their adaptable mechanical, electrical, thermal, and other functional properties. The choice of constituent materials largely determines these properties: for example, long fibers redistribute stress efficiently, highly conductive filler particles impart their conductivity to the material, and combinations of ionic and electrically conductive fillers with energy storage materials increase the capacity of battery electrodes. The performance of these composites, however, is highly dependent on the internal arrangement of particles. Consequently, controlling this internal structure enables property improvements and novel functionalities. In particular, combining microstructure control with the design freedom of 3D printing presents opportunities to maximize the performance of functional components by spatially modulating properties and their directionality (e.g. reinforcing high-stress regions, prescribing electrical interconnects, or directing heat away from hot spots), as well as introducing novel combinations of properties.To develop this structural control in printed materials, this work utilizes pressure fields to assemble filler particles into patterns within composites during 3D printing. Particle patterns are engineered to improve material properties by leveraging microscopic acoustic forces on particles, tailoring the particle arrangement for improvements in the functionality of the material. This acoustic patterning technique is integrated into 3D printing with attention to processing constraints (e.g. component and feature sizes, material properties, cost, throughput rate, etc.) required in existing and emerging technological applications. In particular, 3D printed composites with high electrical or thermal conductivity, which are simultaneously mechanically flexible or strain-tolerant, are

In the latest experimental success, NbOI2 two-dimensional (2D) crystals with anisotropic electronic and optical properties have been fabricated (Adv. Mater. 33 (2021), 2101505). In this work inspired by the aforementioned accomplishment, we conduct first-principles calculations to explore the mechanical, electronic, and optical properties of NbOX2 (X = Cl, Br, I) nanosheets. We show that individual layers in these systems are weakly bonded, with exfoliation energies of 0.22, 0.23, and 0.24 J m-2, for the isolation of the NbOCl2, NbOBr2, and NbOI2 monolayers, respectively, distinctly lower than those of the graphene. The optoelectronic properties of the single-layer, bilayer, and bulk NbOCl2, NbOBr2, and NbOI2 crystals are investigated via density functional theory calculations with the HSE06 approach. Our results indicate that the layered bulk NbOCl2, NbOBr2, and NbOI2 crystals are indirect gap semiconductors, with band gaps of 1.79, 1.69, and 1.60 eV, respectively. We found a slight increase in the electronic gap for the monolayer and bilayer systems due to electron confinement at the nanoscale. Our results show that the monolayer and bilayer of these novel 2D compounds show suitable valence and conduction band edge positions for visible-light-driven water splitting reactions. The first absorption peaks of these novel monolayers along the in-plane polarization are located in the visible range of light which can be a promising feature to design advanced nanoelectronics. We found that the studied 2D systems exhibit highly anisotropic mechanical and optical properties. The presented first-principles results provide a comprehensive vision about direction-dependent mechanical and optical properties of NbOX2 (X = Cl, Br, I) nanosheets.

Peripheral nerve regeneration with large defects needs innovative design of nerve guidance conduits (NGCs) which possess anisotropic guidance, electrical induction and right mechanical properties in one. Herein, we present, for the first time, facile fabrication and efficient neural differentiation guidance of anisotropic, conductive, self-snapping, hydrogel-based NGCs. The hydrogels were fabricated via crosslinking of graphitic carbon nitride (g-C3N4) upon exposure with blue light, incorporated with graphene oxide (GO). Incorporation of GO and in situ reduction greatly enhanced surface charges, while decayed light penetration endowed the hydrogel with an intriguing self-snapping feature by the virtue of a crosslinking gradient. The hydrogels were in the optimal mechanical stiffness range for peripheral nerve regeneration and supported normal viability and proliferation of neural cells. The PC12 cells differentiated on the electroactive g-C3N4 H/rGO3 (3 mg/mL GO loading) hydrogel presented 47% longer neurite length than that of the pristine g-C3N4 H hydrogel. Furthermore, the NGC with aligned microchannels was successfully fabricated using sacrificial melt electrowriting (MEW) moulding, the anisotropic microchannels of the 10 mu m width showed optimal neurite guidance. Such anisotropic, electroactive, self-snapping NGCs may possess great potential for repairing peripheral nerve injuries., QC 20221102

The dynamic behaviour of a novel anisotropic cellular micro-structural geometry derived from the basic symmetric Kelvin cell is discussed for varying relative density. The cells are arranged in a cubic array and the dynamic response is studied in a classical seismic mass setup using beam elements to represent the ligaments of the cell. The eigenfrequencies and the eigenmodes of the cellular array are computed together with forced response simulations where a proportional damping model of the Young's modulus for the cell ligaments is assumed. The frequency dependence of the damping is based on a fractional derivative representation. Using a recently developed inversion method, equivalent, homogenised solid material models of the cellular array are discussed with the associated equivalent elastic properties given in terms of the 21 elastic constants of the Hooke's tensor. For the equivalent solid material models, the eigenfrequencies and eigenmodes are computed, and forced response simulations are performed assuming the same type of proportionality in the damping as the cellular array, for the same seismic mass setup. The correlation, between the eigenfrequencies and the eigenmodes, shows an overall interesting agreement between the cellular and the equivalent solid model for the quite complex deformation shapes observed. The forced response results indicate that the equivalent solid modelling accurately represents the global dynamics of the anisotropic cellular array, but needs to be further refined when local shearing deformation within the individual cells starts to be dominating., QC 20221024

Multilayer panels consisting of a load carrying structure, a porous material for thermal and acoustic insulation and an interior trim panel is a very common type of design for vehicles. Weight as well as total build height are usually limiting constraints on the design. The idea of using an anisotropic porous material instead of an isotropic one to improve the sound transmission loss without adding a lot of weight or thickness is explored in the paper. By using a state space formulation of the transfer matrix method transmission loss it is possible to include anisotropic material properties in the calculation. The anisotropic material is modelled by a combination of a simplified analytical model for the acoustic losses and inverse estimation of the 21 independent elastic constants of the Hooke’s tensor. The porous material, which has typical dimensions possible to 3D print, is based on a Kelvin cell micro model that has a controlled degree of anisotropy., Proceedings will be published after the conference taking part 12th-14th September 2022. The conference paper has been submitted.QC 20220909

A method for the calculation of the acoustic performance of open-cell foammaterials is discussed. From a known micro-structural geometry and theconstituent material, the relevant acoustic properties are computed using apreviously published analytical method for the calculation of the dynamicdrag impedance and a previously published method for the calculation of theelastic moduli. These have been combined and are here used to generate thenecessary inputs to a fully anisotropic state space formulation of a TransferMatrix Method (TMM) based solution where only geometry and materialproperties need to be known. From the TMM solution, the sound absorptionand sound transmission loss of multilayer panels including anisotropic opencell materials is estimated. It is shown that the proposed method may beused in an optimization of sound absorption in multi-layer porous materials, where the different layers can have different degrees of anisotropy in theiracoustic and elastic properties. In the current work, the micro-geometry is based on the Kelvin cellwhich then is modified to achieve a controlled degree of anisotropy. The method has been validated by comparing the absorption and sound transmission loss for isotropic porous materials have been compared to equivalent structures computed with a commercial TMM mode, including a porous material which has been fully characterized with regard to previously published Johnson-Champoux-Allard parameters. In addition the calculated dynamic drag impedance has been compared to measurements conductedon a series of small samples with a defined 3D printed micro geometry forwhich the static flow resistivity has been measured. The method in general underestimates the dynamic drag impedance compared to the static flowresistivity due to not including the contributions to the losses from the constrictions between the struts close to the cell vertices. All verification showa good degree of agreement, confirming that for open-cell porous materials, En metod för beräkning av de akustiska egenskaperna hos skummaterialmed öppna celler diskuteras. Baserat på en känd mikrogeometri and de ingående materialen kan de relevanta akustiska egenskaperna beräknas. Metoden bygger på arbeten för dynamiskt flödesmotstånd och beräkning avelastiska egenskaper som publicerats tidigare. De egenskaperna ¨ar inkluderade i en fullt anisotrop formulering för lösning av en state space TransferMatrix Method (TMM) beräkning, där endast geometri och material krävs som indata. Från TMM-beräkningen kan ljudabsorption och ljudtransmission i konstruktioner med flera skikt uppskattas. Möjligheten att göra optimering av ljudabsorption av flera kombinerade skikt med olika grader avanisotropi i beräknade akustiska och styvhetsegenskaper har visats. I detta arbete baseras mikrogeometrin på en Kelvincell-geometri, som modifierats för att uppnå en definerad grad av anisotropi. Metoden har validerats genom att jämföra absorption och ljudtransmission av ekvivalenta strukturer beräknade med ett kommersiellt TMM-program på ett skum-material som karaktäriserats med avseende på publicerade Johnson-Champoux-Allard parametrar. Dessutom har de beräknade dynamiska flödesmotstånden jämförts medmätningar av statiskt flödesmotstånd på små prov tillverkade med 3D-printer. Metoden underskattar generellt flödesmotståndet jämfört med det uppmätta statiska flödesmotståndet eftersom inverkan av trånga sektioner mellan mikro-strävorna negligeras. All verifiering visar en god nivå av överensstämmelse och bekräftar att metoden skulle kunna användas för att göra nya typer av akustiska konstruktioner i flera lager med porösa material med öppna celler och relativt hög porositet ., QC 220905, VinnExcellence Center for ECO2 Vehicle design, VinnExcellence Center for ECO2 Vehicle design

A method for the calculation of the acoustic performance of open-cell foammaterials is discussed. From a known micro-structural geometry and theconstituent material, the relevant acoustic properties are computed using apreviously published analytical method for the calculation of the dynamicdrag impedance and a previously published method for the calculation of theelastic moduli. These have been combined and are here used to generate thenecessary inputs to a fully anisotropic state space formulation of a TransferMatrix Method (TMM) based solution where only geometry and materialproperties need to be known. From the TMM solution, the sound absorptionand sound transmission loss of multilayer panels including anisotropic opencell materials is estimated. It is shown that the proposed method may beused in an optimization of sound absorption in multi-layer porous materials, where the different layers can have different degrees of anisotropy in theiracoustic and elastic properties. In the current work, the micro-geometry is based on the Kelvin cellwhich then is modified to achieve a controlled degree of anisotropy. The method has been validated by comparing the absorption and sound transmission loss for isotropic porous materials have been compared to equivalent structures computed with a commercial TMM mode, including a porous material which has been fully characterized with regard to previously published Johnson-Champoux-Allard parameters. In addition the calculated dynamic drag impedance has been compared to measurements conductedon a series of small samples with a defined 3D printed micro geometry forwhich the static flow resistivity has been measured. The method in general underestimates the dynamic drag impedance compared to the static flowresistivity due to not including the contributions to the losses from the constrictions between the struts close to the cell vertices. All verification showa good degree of agreement, confirming that for open-cell porous materials, En metod för beräkning av de akustiska egenskaperna hos skummaterialmed öppna celler diskuteras. Baserat på en känd mikrogeometri and de ingående materialen kan de relevanta akustiska egenskaperna beräknas. Metoden bygger på arbeten för dynamiskt flödesmotstånd och beräkning avelastiska egenskaper som publicerats tidigare. De egenskaperna ¨ar inkluderade i en fullt anisotrop formulering för lösning av en state space TransferMatrix Method (TMM) beräkning, där endast geometri och material krävs som indata. Från TMM-beräkningen kan ljudabsorption och ljudtransmission i konstruktioner med flera skikt uppskattas. Möjligheten att göra optimering av ljudabsorption av flera kombinerade skikt med olika grader avanisotropi i beräknade akustiska och styvhetsegenskaper har visats. I detta arbete baseras mikrogeometrin på en Kelvincell-geometri, som modifierats för att uppnå en definerad grad av anisotropi. Metoden har validerats genom att jämföra absorption och ljudtransmission av ekvivalenta strukturer beräknade med ett kommersiellt TMM-program på ett skum-material som karaktäriserats med avseende på publicerade Johnson-Champoux-Allard parametrar. Dessutom har de beräknade dynamiska flödesmotstånden jämförts medmätningar av statiskt flödesmotstånd på små prov tillverkade med 3D-printer. Metoden underskattar generellt flödesmotståndet jämfört med det uppmätta statiska flödesmotståndet eftersom inverkan av trånga sektioner mellan mikro-strävorna negligeras. All verifiering visar en god nivå av överensstämmelse och bekräftar att metoden skulle kunna användas för att göra nya typer av akustiska konstruktioner i flera lager med porösa material med öppna celler och relativt hög porositet ., QC 220905, VinnExcellence Center for ECO2 Vehicle design, VinnExcellence Center for ECO2 Vehicle design

Anisotropic elasticity and inelasticity is of relevance in many practical applications. The Eulerian formulation for anisotropic elastic and inelastic response based on microstructural vectors is used here to model an injection-moulded low-density polyethylene. In contrast with Lagrangian models of inelasticity, the Eulerian formulation is insensitive to arbitrariness of the reference and intermediate configurations as well as to measures of total and inelastic deformations. A specific strain-space-type anisotropic yield function is proposed that depends on anisotropic measures of elastic deformation and anisotropic hardening variables. Use is also made of a rate-independent model with a smooth elastic-inelastic transition. The material parameters were calibrated to reproduce uniaxial test data for loading in three directions in the moulding plane. In addition, a strongly objective numerical implementation is presented and used to simulate stretching of a plate with a circular hole. In contrast with metals, this polyethylene experiences elastic deformations of about 10%. Although the inelastic spin rate could not be determined by the available test data, simulations of loadings in different material directions yield observable influences of inelastic spin rate.

Dans ce présent travail, quatre classes de contributions sont réalisées: • Contribution à la modélisation numérique de la conduction de la chaleur, en régime transitoire, des solides multi-matériaux caractérisés par des tenseurs de conductivité thermique anisotrope et de natures différentes. L’équation de la conduction de la chaleur est exprimée par la variable température. • Contribution à la modélisation numérique de la conduction de la chaleur, en régime transitoire, des solides multi-matériaux caractérisés par des tenseurs de conductivité thermique anisotrope et de natures différentes, avec ou sans changement de phase. L’équation de la conduction de la chaleur est exprimée par la variable enthalpie volumique. • Contribution à la modélisation numérique de la conduction de la chaleur, en régime stationnaire, par la transformée de Kirchhoff : i) cas de conduction-convection et ii) cas de conduction-convection-radiation (conditions aux limite). • Contribution à la modélisation de chauffage diélectrique des biocomposites (matériaux diélectriques) anisotrope et non linéaire avec changement de phase. Dans le cas de la résolution numérique de l’équation de la conduction en fonction de la température, la méthode implicite des éléments finis est considérée. Pour l'amélioration de l'efficacité et de la précision de la solution numérique, la stratégie prédicteur/correcteur est utilisé [35]. L'approche proposée est validée pour cinq situations : 1. Distribution de la température analytique dans un cylindre anisotrope avec un transfert de chaleur convectif (avec variation circonférentielle). 2. Distribution de la température analytique dans une sphère anisotrope avec un transfert de chaleur convectif (avec variation circonférentielle). 3. Distribution de la température numérique pour une plaque carrée constituée de deux matériaux différents, dont l'un est un matériau isotrope, tandis que le second est orthotrope. 4. Chauffage anisotrope du bois (en tenant compte du changement

We study the pointwise multiplier property of the characteristic function of the half-space on weighted mixed-norm anisotropic vector-valued function spaces of Bessel potential and Triebel–Lizorkin type., Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public., Analysis

Shape morphing materials, especially those fabricated by 4D printing, are gaining much attention due to their versatility of actuation and capability of being programmed in advance. These materials become particularly interesting for biomedical applications where implant materials could be remotely actuated, exerting a force on the surrounding tissues and cells. However, applications in this field have been restricted due to the biocompatibility of the materials and the character of the required stimuli, generally not compatible with physiological environments. Magnetic nanoparticles (MNPs) represent a great opportunity to this end; however, the actuation results in a uniform movement toward the magnet that requires anchoring of the object. Here, for the first time, the application of anisotropic Fe3O4 MNPs is described, and synthesized by a novel and easy route, that can be aligned on pre-defined patterns within objects printed by digital light processing, resulting in materials that can be actuated remotely (4D printing). These nanoparticles (178 nm x 55 nm), show good biocompatibility when directly seeded on top of human mesenchymal stem cells, despite being uptaken. Most importantly, the alignment of the MNPs can tune the movement of fabricated nanocomposite materials, resulting in complex movements of attraction or repulsion depending on the direction of the applied magnetic field.

A method for the calculation of the acoustic performance of open-cell foammaterials is discussed. From a known micro-structural geometry and theconstituent material, the relevant acoustic properties are computed using apreviously published analytical method for the calculation of the dynamicdrag impedance and a previously published method for the calculation of theelastic moduli. These have been combined and are here used to generate thenecessary inputs to a fully anisotropic state space formulation of a TransferMatrix Method (TMM) based solution where only geometry and materialproperties need to be known. From the TMM solution, the sound absorptionand sound transmission loss of multilayer panels including anisotropic opencell materials is estimated. It is shown that the proposed method may beused in an optimization of sound absorption in multi-layer porous materials, where the different layers can have different degrees of anisotropy in theiracoustic and elastic properties. In the current work, the micro-geometry is based on the Kelvin cellwhich then is modified to achieve a controlled degree of anisotropy. The method has been validated by comparing the absorption and sound transmission loss for isotropic porous materials have been compared to equivalent structures computed with a commercial TMM mode, including a porous material which has been fully characterized with regard to previously published Johnson-Champoux-Allard parameters. In addition the calculated dynamic drag impedance has been compared to measurements conductedon a series of small samples with a defined 3D printed micro geometry forwhich the static flow resistivity has been measured. The method in general underestimates the dynamic drag impedance compared to the static flowresistivity due to not including the contributions to the losses from the constrictions between the struts close to the cell vertices. All verification showa good degree of agreement, confirming that for open-cell porous materials, En metod för beräkning av de akustiska egenskaperna hos skummaterialmed öppna celler diskuteras. Baserat på en känd mikrogeometri and de ingående materialen kan de relevanta akustiska egenskaperna beräknas. Metoden bygger på arbeten för dynamiskt flödesmotstånd och beräkning avelastiska egenskaper som publicerats tidigare. De egenskaperna ¨ar inkluderade i en fullt anisotrop formulering för lösning av en state space TransferMatrix Method (TMM) beräkning, där endast geometri och material krävs som indata. Från TMM-beräkningen kan ljudabsorption och ljudtransmission i konstruktioner med flera skikt uppskattas. Möjligheten att göra optimering av ljudabsorption av flera kombinerade skikt med olika grader avanisotropi i beräknade akustiska och styvhetsegenskaper har visats. I detta arbete baseras mikrogeometrin på en Kelvincell-geometri, som modifierats för att uppnå en definerad grad av anisotropi. Metoden har validerats genom att jämföra absorption och ljudtransmission av ekvivalenta strukturer beräknade med ett kommersiellt TMM-program på ett skum-material som karaktäriserats med avseende på publicerade Johnson-Champoux-Allard parametrar. Dessutom har de beräknade dynamiska flödesmotstånden jämförts medmätningar av statiskt flödesmotstånd på små prov tillverkade med 3D-printer. Metoden underskattar generellt flödesmotståndet jämfört med det uppmätta statiska flödesmotståndet eftersom inverkan av trånga sektioner mellan mikro-strävorna negligeras. All verifiering visar en god nivå av överensstämmelse och bekräftar att metoden skulle kunna användas för att göra nya typer av akustiska konstruktioner i flera lager med porösa material med öppna celler och relativt hög porositet ., QC 220905, VinnExcellence Center for ECO2 Vehicle design, VinnExcellence Center for ECO2 Vehicle design

A method for the calculation of the acoustic performance of open-cell foammaterials is discussed. From a known micro-structural geometry and theconstituent material, the relevant acoustic properties are computed using apreviously published analytical method for the calculation of the dynamicdrag impedance and a previously published method for the calculation of theelastic moduli. These have been combined and are here used to generate thenecessary inputs to a fully anisotropic state space formulation of a TransferMatrix Method (TMM) based solution where only geometry and materialproperties need to be known. From the TMM solution, the sound absorptionand sound transmission loss of multilayer panels including anisotropic opencell materials is estimated. It is shown that the proposed method may beused in an optimization of sound absorption in multi-layer porous materials, where the different layers can have different degrees of anisotropy in theiracoustic and elastic properties. In the current work, the micro-geometry is based on the Kelvin cellwhich then is modified to achieve a controlled degree of anisotropy. The method has been validated by comparing the absorption and sound transmission loss for isotropic porous materials have been compared to equivalent structures computed with a commercial TMM mode, including a porous material which has been fully characterized with regard to previously published Johnson-Champoux-Allard parameters. In addition the calculated dynamic drag impedance has been compared to measurements conductedon a series of small samples with a defined 3D printed micro geometry forwhich the static flow resistivity has been measured. The method in general underestimates the dynamic drag impedance compared to the static flowresistivity due to not including the contributions to the losses from the constrictions between the struts close to the cell vertices. All verification showa good degree of agreement, confirming that for open-cell porous materials, En metod för beräkning av de akustiska egenskaperna hos skummaterialmed öppna celler diskuteras. Baserat på en känd mikrogeometri and de ingående materialen kan de relevanta akustiska egenskaperna beräknas. Metoden bygger på arbeten för dynamiskt flödesmotstånd och beräkning avelastiska egenskaper som publicerats tidigare. De egenskaperna ¨ar inkluderade i en fullt anisotrop formulering för lösning av en state space TransferMatrix Method (TMM) beräkning, där endast geometri och material krävs som indata. Från TMM-beräkningen kan ljudabsorption och ljudtransmission i konstruktioner med flera skikt uppskattas. Möjligheten att göra optimering av ljudabsorption av flera kombinerade skikt med olika grader avanisotropi i beräknade akustiska och styvhetsegenskaper har visats. I detta arbete baseras mikrogeometrin på en Kelvincell-geometri, som modifierats för att uppnå en definerad grad av anisotropi. Metoden har validerats genom att jämföra absorption och ljudtransmission av ekvivalenta strukturer beräknade med ett kommersiellt TMM-program på ett skum-material som karaktäriserats med avseende på publicerade Johnson-Champoux-Allard parametrar. Dessutom har de beräknade dynamiska flödesmotstånden jämförts medmätningar av statiskt flödesmotstånd på små prov tillverkade med 3D-printer. Metoden underskattar generellt flödesmotståndet jämfört med det uppmätta statiska flödesmotståndet eftersom inverkan av trånga sektioner mellan mikro-strävorna negligeras. All verifiering visar en god nivå av överensstämmelse och bekräftar att metoden skulle kunna användas för att göra nya typer av akustiska konstruktioner i flera lager med porösa material med öppna celler och relativt hög porositet ., QC 220905, VinnExcellence Center for ECO2 Vehicle design, VinnExcellence Center for ECO2 Vehicle design

Anisotropic elasticity and inelasticity is of relevance in many practical applications. The Eulerian formulation for anisotropic elastic and inelastic response based on microstructural vectors is used here to model an injection-moulded low-density polyethylene. In contrast with Lagrangian models of inelasticity, the Eulerian formulation is insensitive to arbitrariness of the reference and intermediate configurations as well as to measures of total and inelastic deformations. A specific strain-space-type anisotropic yield function is proposed that depends on anisotropic measures of elastic deformation and anisotropic hardening variables. Use is also made of a rate-independent model with a smooth elastic-inelastic transition. The material parameters were calibrated to reproduce uniaxial test data for loading in three directions in the moulding plane. In addition, a strongly objective numerical implementation is presented and used to simulate stretching of a plate with a circular hole. In contrast with metals, this polyethylene experiences elastic deformations of about 10%. Although the inelastic spin rate could not be determined by the available test data, simulations of loadings in different material directions yield observable influences of inelastic spin rate.

Anisotropic elasticity and inelasticity is of relevance in many practical applications. The Eulerian formulation for anisotropic elastic and inelastic response based on microstructural vectors is used here to model an injection-moulded low-density polyethylene. In contrast with Lagrangian models of inelasticity, the Eulerian formulation is insensitive to arbitrariness of the reference and intermediate configurations as well as to measures of total and inelastic deformations. A specific strain-space-type anisotropic yield function is proposed that depends on anisotropic measures of elastic deformation and anisotropic hardening variables. Use is also made of a rate-independent model with a smooth elastic-inelastic transition. The material parameters were calibrated to reproduce uniaxial test data for loading in three directions in the moulding plane. In addition, a strongly objective numerical implementation is presented and used to simulate stretching of a plate with a circular hole. In contrast with metals, this polyethylene experiences elastic deformations of about 10%. Although the inelastic spin rate could not be determined by the available test data, simulations of loadings in different material directions yield observable influences of inelastic spin rate.

The petrophysical and dielectric properties for both carbonate and saturated sandstone with monovalent and divalent electrolyte they are accurately modeling of anisotropic dielectric properties has been the major research area in oil and gas industries for effective sweep efficiency. The reservoir petrophysical properties consist of cation and anion exchange capacity on a specific area and the sandstone porosity. The transportation of the ions is a charge carrier that mediates conduction in the pore fluids under the electrical double layers that exist between the minerals and the pore fluids interface. The dielectric anisotropic and the frequency-dependent behavior of reservoir sandstone with the minerals will be fully elucidated, it was revealed from the result obtained the effect of the anisotropic dielectric properties on the reservoir sandstone based on the influx of NaCl electrolyte modify the wettability of rock formation from oil-wet to water-wet at 9000 and 11000 ppm concentration with the aids of the electromagnetic field. The resistivity index of the reservoir sandstone reduces with the increase of electrolyte to the system.

Producción Científica, Self-assembling bioinks offer the possibility to biofabricate with molecular precision, hierarchical control, and biofunctionality. For this to become a reality with widespread impact, it is essential to engineer these ink systems ensuring reproducibility and providing suitable standardization. We have reported a self-assembling bioink based on disorder-to-order transitions of an elastin-like recombinamer (ELR) to co-assemble with graphene oxide (GO). Here, we establish reproducible processes, optimize printing parameters for its use as a bioink, describe new advantages that the self-assembling bioink can provide, and demonstrate how to fabricate novel structures with physiological relevance. We fabricate capillary-like structures with resolutions down to ∼10 µm in diameter and ∼2 µm thick tube walls and use both experimental and finite element analysis to characterize the printing conditions, underlying interfacial diffusion-reaction mechanism of assembly, printing fidelity, and material porosity and permeability. We demonstrate the capacity to modulate the pore size and tune the permeability of the resulting structures with and without human umbilical vascular endothelial cells. Finally, the potential of the ELR-GO bioink to enable supramolecular fabrication of biomimetic structures was demonstrated by printing tubes exhibiting walls with progressively different structure and permeability., The work was supported by the ERC Starting Grant (STROFUNSCAFF), the Medical Research Council (UK Regenerative Medicine Platform Acellular/Smart Materials 3D Architecture, MR/R015651/1), and the AO Foundation AOCMF-17-19M.

We show that a continuous potential q can be constructively determined from the knowledge of the Dirichlet–to–Neumann map for the Schrödinger operator −Δg+q on a conformally transversally anisotropic manifold of dimension ≥3, provided that the geodesic ray transform on the transversal manifold is constructively invertible. This is a constructive counterpart of the uniqueness result of [12]. A crucial role in our reconstruction procedure is played by a constructive determination of the boundary traces of suitable complex geometric optics solutions based on Gaussian beams quasimodes concentrated along non-tangential geodesics on the transversal manifold, which enjoy uniqueness properties. This is achieved by applying the simplified version of the approach of [33] to our setting. We also identify the main space introduced in [33] with a standard Sobolev space on the boundary of the manifold. Another ingredient in the proof of our result is a reconstruction formula for the boundary trace of a continuous potential from the knowledge of the Dirichlet–to–Neumann map. © 2021 Elsevier Inc.

Plasmonic nanostructures have attracted significant attention due to their tunable optical properties and broad applications in chemical sensing, photothermal therapy, and energy conversions. The plasmonic properties of the nanoparticles are sensitive to the size, morphology, and composition of the metal nanoparticles. Although the wet chemistry synthesis of plasmonic nanoparticles with well-controlled geometries has been widely studied, the systematic tuning of novel plasmonic nanostructures can broaden the application scenarios. It brings more complexity to the optical responses of the plasmonic nanostructures. Besides, the synthesis of these novel structures deepens our understanding of the crystal growth mechanisms and light-matter interaction. In this dissertation, we discuss the tuning of optical properties of plasmonic nanoparticles through morphology control, magnetic manipulation, and exploring unconventional materials for the plasmonic solar-energy conversion.In the aspect of morphology control, we achieved island growth of Au on Au nanostructures by introducing lattice mismatch through a thin layer of Pd coating on the substrate. The location of the islands can be controlled by changing the distribution of Pd, and the island features including size, distance, and wetting degree of the islands can be systematically controlled. In the aspect of the dynamic orientational control of anisotropic nanoparticles, plasmonic/magnetic nanocomposites were fabricated, and the magnetic tuning of the nanoparticles was achieved. In this dissertation, we broke the connection between the morphology of the plasmonic and the magnetic component, which was a major challenge in the synthesis of plasmonic/magnetic nanocomposites since it limited the choice of both plasmonic and magnetic components. Furthermore, alternative plasmonic metals were explored, and we demonstrated the potential and advantages of Ni in the solar steam generation performance. A high energy conversion eff

This paper introduces a methodology to study the anisotropic elastic constants of technical phenylene polysulfide thermoplastic (PPS), printed using fused deposition modeling (FDM) in order to provide designers with a guide to achieve the required mechanical properties in a printed part. The properties given by the manufacturer are usually taken from injected samples and these are not the real properties for printed parts. Compared to other plastic materials, PPS offers higher mechanical and thermal resistance, lower moisture absorption, higher dimensional stability, is highly resistant to chemical attacks and environmental aging, and its fireproof performance is good. One of the main difficulties presented when calculating and designing for FDM printing is that printed parts present anisotropic behavior i.e., they do not have the same properties in different directions. Haltera-type samples were printed in the three manufacturing directions according to optimum parameters for material printing, aimed at calculating the anisotropic matrix of the material. The samples were tested in order to meet standards and values for elastic modulus, shear modulus and tensile strength were obtained, using Digital Image Correlation System to measure the deformations. An approximated transversally isotropic matrix was defined using the obtained values. The fracture was analyzed using SEM microscopy to check whether the piece was printed correctly. Finally, the obtained matrix was validated by a flexural test and a finite element simulation.

Producción Científica, Self-assembling bioinks offer the possibility to biofabricate with molecular precision, hierarchical control, and biofunctionality. For this to become a reality with widespread impact, it is essential to engineer these ink systems ensuring reproducibility and providing suitable standardization. We have reported a self-assembling bioink based on disorder-to-order transitions of an elastin-like recombinamer (ELR) to co-assemble with graphene oxide (GO). Here, we establish reproducible processes, optimize printing parameters for its use as a bioink, describe new advantages that the self-assembling bioink can provide, and demonstrate how to fabricate novel structures with physiological relevance. We fabricate capillary-like structures with resolutions down to ∼10 µm in diameter and ∼2 µm thick tube walls and use both experimental and finite element analysis to characterize the printing conditions, underlying interfacial diffusion-reaction mechanism of assembly, printing fidelity, and material porosity and permeability. We demonstrate the capacity to modulate the pore size and tune the permeability of the resulting structures with and without human umbilical vascular endothelial cells. Finally, the potential of the ELR-GO bioink to enable supramolecular fabrication of biomimetic structures was demonstrated by printing tubes exhibiting walls with progressively different structure and permeability., The work was supported by the ERC Starting Grant (STROFUNSCAFF), the Medical Research Council (UK Regenerative Medicine Platform Acellular/Smart Materials 3D Architecture, MR/R015651/1), and the AO Foundation AOCMF-17-19M.

This paper introduces a methodology to study the anisotropic elastic constants of technical phenylene polysulfide thermoplastic (PPS), printed using fused deposition modeling (FDM) in order to provide designers with a guide to achieve the required mechanical properties in a printed part. The properties given by the manufacturer are usually taken from injected samples and these are not the real properties for printed parts. Compared to other plastic materials, PPS offers higher mechanical and thermal resistance, lower moisture absorption, higher dimensional stability, is highly resistant to chemical attacks and environmental aging, and its fireproof performance is good. One of the main difficulties presented when calculating and designing for FDM printing is that printed parts present anisotropic behavior i.e., they do not have the same properties in different directions. Haltera-type samples were printed in the three manufacturing directions according to optimum parameters for material printing, aimed at calculating the anisotropic matrix of the material. The samples were tested in order to meet standards and values for elastic modulus, shear modulus and tensile strength were obtained, using Digital Image Correlation System to measure the deformations. An approximated transversally isotropic matrix was defined using the obtained values. The fracture was analyzed using SEM microscopy to check whether the piece was printed correctly. Finally, the obtained matrix was validated by a flexural test and a finite element simulation.

Vehicle structures such as train floors or car roofs are usually built as multi-layer panels, where a foam is placed between a load-carrying structure and an interior panel. The foam adds acoustical and thermal performance, but very little weight. In most contributions introducing foams for acoustic treatment, these have been considered isotropic, with acoustic losses mainly dependingon properties in the thickness direction. Another mechanism investigated here is the possibilityfor the acoustic flow in the foam to change from acting only in the thickness direction but rather to be re-directed to also travel in-plane, where dimensions are substantially larger than in the thickness direction, permitting more losses as the wave travels through the material. That kind of effect would result in higher acoustic losses without increasing the thickness of the vehicle panel and better use of the allowable space to achieve acoustic and functional requirements, i.e. a better functional density. A first step is to investigate how the absorption properties of an anisotropic foam differs from an isotropic foam. The chosen approach is to use an analytical micro-modelto calculate the dynamic drag impedance (flow resistivity on micro-scale) for an anisotropic opencell foam material. Based on a simple micro-scale geometry of Kelvin cells, it has been shown that simple cell alterations to the micro-geometry, such as stretching, twisting and tilting results in an anisotropic foam structure. The anisotropic flow resistivity tensor is not diagonal and uniform, but different directions can have different magnitudes and it can display off-diagonal coupling terms. The influence of such micro-scale distortions on the flow resistivity, and on the resulting sound absorption is investigated with the purpose of improving the acoustic performance without adding volume. Future steps include to modify the functional density and tailor the sound transmission loss to a specific application., QC 20220315

Plasmonic nanostructures have attracted significant attention due to their tunable optical properties and broad applications in chemical sensing, photothermal therapy, and energy conversions. The plasmonic properties of the nanoparticles are sensitive to the size, morphology, and composition of the metal nanoparticles. Although the wet chemistry synthesis of plasmonic nanoparticles with well-controlled geometries has been widely studied, the systematic tuning of novel plasmonic nanostructures can broaden the application scenarios. It brings more complexity to the optical responses of the plasmonic nanostructures. Besides, the synthesis of these novel structures deepens our understanding of the crystal growth mechanisms and light-matter interaction. In this dissertation, we discuss the tuning of optical properties of plasmonic nanoparticles through morphology control, magnetic manipulation, and exploring unconventional materials for the plasmonic solar-energy conversion.In the aspect of morphology control, we achieved island growth of Au on Au nanostructures by introducing lattice mismatch through a thin layer of Pd coating on the substrate. The location of the islands can be controlled by changing the distribution of Pd, and the island features including size, distance, and wetting degree of the islands can be systematically controlled. In the aspect of the dynamic orientational control of anisotropic nanoparticles, plasmonic/magnetic nanocomposites were fabricated, and the magnetic tuning of the nanoparticles was achieved. In this dissertation, we broke the connection between the morphology of the plasmonic and the magnetic component, which was a major challenge in the synthesis of plasmonic/magnetic nanocomposites since it limited the choice of both plasmonic and magnetic components. Furthermore, alternative plasmonic metals were explored, and we demonstrated the potential and advantages of Ni in the solar steam generation performance. A high energy conversion eff

Producción Científica, Self-assembling bioinks offer the possibility to biofabricate with molecular precision, hierarchical control, and biofunctionality. For this to become a reality with widespread impact, it is essential to engineer these ink systems ensuring reproducibility and providing suitable standardization. We have reported a self-assembling bioink based on disorder-to-order transitions of an elastin-like recombinamer (ELR) to co-assemble with graphene oxide (GO). Here, we establish reproducible processes, optimize printing parameters for its use as a bioink, describe new advantages that the self-assembling bioink can provide, and demonstrate how to fabricate novel structures with physiological relevance. We fabricate capillary-like structures with resolutions down to ∼10 µm in diameter and ∼2 µm thick tube walls and use both experimental and finite element analysis to characterize the printing conditions, underlying interfacial diffusion-reaction mechanism of assembly, printing fidelity, and material porosity and permeability. We demonstrate the capacity to modulate the pore size and tune the permeability of the resulting structures with and without human umbilical vascular endothelial cells. Finally, the potential of the ELR-GO bioink to enable supramolecular fabrication of biomimetic structures was demonstrated by printing tubes exhibiting walls with progressively different structure and permeability., The work was supported by the ERC Starting Grant (STROFUNSCAFF), the Medical Research Council (UK Regenerative Medicine Platform Acellular/Smart Materials 3D Architecture, MR/R015651/1), and the AO Foundation AOCMF-17-19M.

Producción Científica, Self-assembling bioinks offer the possibility to biofabricate with molecular precision, hierarchical control, and biofunctionality. For this to become a reality with widespread impact, it is essential to engineer these ink systems ensuring reproducibility and providing suitable standardization. We have reported a self-assembling bioink based on disorder-to-order transitions of an elastin-like recombinamer (ELR) to co-assemble with graphene oxide (GO). Here, we establish reproducible processes, optimize printing parameters for its use as a bioink, describe new advantages that the self-assembling bioink can provide, and demonstrate how to fabricate novel structures with physiological relevance. We fabricate capillary-like structures with resolutions down to ∼10 µm in diameter and ∼2 µm thick tube walls and use both experimental and finite element analysis to characterize the printing conditions, underlying interfacial diffusion-reaction mechanism of assembly, printing fidelity, and material porosity and permeability. We demonstrate the capacity to modulate the pore size and tune the permeability of the resulting structures with and without human umbilical vascular endothelial cells. Finally, the potential of the ELR-GO bioink to enable supramolecular fabrication of biomimetic structures was demonstrated by printing tubes exhibiting walls with progressively different structure and permeability., The work was supported by the ERC Starting Grant (STROFUNSCAFF), the Medical Research Council (UK Regenerative Medicine Platform Acellular/Smart Materials 3D Architecture, MR/R015651/1), and the AO Foundation AOCMF-17-19M.

The simulation of structural problems involving the deformations of volumetric bodies is of paramount importance in many areas of engineering. Although the use of tetrahedral elements is extremely appealing, tetrahedral discretisations are generally known as very stiff and are hence often avoided in typical simulation workflows. The development of mixed displacement–pressure approaches has allowed to effectively overcome this problem leading to a class of locking-free elements which can effectively compete with hexahedral discretisations while retaining obvious advantages in the mesh generation step. Despite such advantages the adoption of the technology within commercial codes is not yet pervasive. This can be attributed to two different reasons: the difficulty in making use of standard constitutive libraries and the implied continuity of the pressure, which makes the application of the method questionable in the context of multi-material problems. Current paper proposes the adoption of the volumetric strain instead of the pressure as a nodal value. Such choice leads to the definition of a modified strain making the use of standard strain-driven constitutive laws straightforward. At the same time, the continuity of the volumetric strain across multimaterial interfaces can be understood as a sort of kinematic constraint (stresses can still remain discontinuous across material interfaces). The new element also opens the door to the use of anisotropic constitutive laws, which are typically problematic in the context of mixed elements., This research has been partly supported by the European Commission (EC) through the project ExaQUte (H2020-FETHPC-2016-2017-800898). The authors also acknowledge financial support from the Spanish Ministry of Economy and Competitiveness, through the “Severo Ochoa Programme for Centres of Excellence in R& D” (CEX2018-000797-S). R. Codina acknowledges the support received from the ICREA Acadèmia Research Program, from the Catalan Government ., Peer Reviewed, Postprint (author's final draft)

This paper introduces a methodology to study the anisotropic elastic constants of technical phenylene polysulfide thermoplastic (PPS), printed using fused deposition modeling (FDM) in order to provide designers with a guide to achieve the required mechanical properties in a printed part. The properties given by the manufacturer are usually taken from injected samples and these are not the real properties for printed parts. Compared to other plastic materials, PPS offers higher mechanical and thermal resistance, lower moisture absorption, higher dimensional stability, is highly resistant to chemical attacks and environmental aging, and its fireproof performance is good. One of the main difficulties presented when calculating and designing for FDM printing is that printed parts present anisotropic behavior i.e., they do not have the same properties in different directions. Haltera-type samples were printed in the three manufacturing directions according to optimum parameters for material printing, aimed at calculating the anisotropic matrix of the material. The samples were tested in order to meet standards and values for elastic modulus, shear modulus and tensile strength were obtained, using Digital Image Correlation System to measure the deformations. An approximated transversally isotropic matrix was defined using the obtained values. The fracture was analyzed using SEM microscopy to check whether the piece was printed correctly. Finally, the obtained matrix was validated by a flexural test and a finite element simulation.

The petrophysical and dielectric properties for both carbonate and saturated sandstone with monovalent and divalent electrolyte they are accurately modeling of anisotropic dielectric properties has been the major research area in oil and gas industries for effective sweep efficiency. The reservoir petrophysical properties consist of cation and anion exchange capacity on a specific area and the sandstone porosity. The transportation of the ions is a charge carrier that mediates conduction in the pore fluids under the electrical double layers that exist between the minerals and the pore fluids interface. The dielectric anisotropic and the frequency-dependent behavior of reservoir sandstone with the minerals will be fully elucidated, it was revealed from the result obtained the effect of the anisotropic dielectric properties on the reservoir sandstone based on the influx of NaCl electrolyte modify the wettability of rock formation from oil-wet to water-wet at 9000 and 11000 ppm concentration with the aids of the electromagnetic field. The resistivity index of the reservoir sandstone reduces with the increase of electrolyte to the system.

The present study deals with modal work that is a type of framework for structural dynamic testing of linear structures. Modal analysis is a powerful tool that works on the modal parameters to ensure the safety of materials and eliminate the failure possibilities. The concept of classification through this study is validated for isotropic and orthotropic materials, reaching up to a 100% accuracy when deploying the machine learning approach between the mode number and the associated frequency of the interrelated variables that were extracted from modal analysis performed by ANSYS. This study shows a new classification method dependent only on the knowledge of resonance frequency of a specific material and opens new directions for future developments to create a single device that can identify and classify different engineering materials.

[EN] The method explained in this paper solves the steady-state of the neutron transport equation for 1D and 2D systems modeled with Cartesian geometry, by using the Discrete Ordinates method SN for the angular discretization and the Finite Difference Method for the spatial discretization. The method applies the multi-group approach for any energy discretization, including upscattering terms. The method solves the steady-state equation by solving a generalized eigenvalue problem by means of a Krylov-Schur method. One of the main advantages of the method is the capability to calculate multiple eigenfunctions. The Discrete Ordinates methodology is used for the angular discretization, which uses a simple formulation involving the angles and direction cosines. The spatial discretization with Finite Difference Method is selected for its simplicity. The method is validated with several one-dimensional benchmark problems and four two dimensional benchmark problems. The results show good agreement with respect to the reference results for all the cases studied.

A computationally efficient method to study the in-plane and out-of-plane dimensional instability of thin paper sheets under the influence of moisture changes is presented. The method explicitly resolves the bonded and the free segments of fibers in the sheet, capturing the effect of anisotropic hygroexpansion at the fiber level. The method is verified against a volumetric model. The importance of longitudinal fiber hygroexpansion is demonstrated in spite of the absolute value of longitudinal hygroexpansion being an order of magnitude lower than the transverse hygroexpansion component. Finally, the method is used to demonstrate the formation of macroscopic sheet curl due to a moisture gradient in structurally uniform sheets in the absence of viscoelastic or plastic constitutive behavior and through-thickness residual stress profiles., Not duplicate with DiVA 1355440QC 20200612

[EN] The method explained in this paper solves the steady-state of the neutron transport equation for 1D and 2D systems modeled with Cartesian geometry, by using the Discrete Ordinates method SN for the angular discretization and the Finite Difference Method for the spatial discretization. The method applies the multi-group approach for any energy discretization, including upscattering terms. The method solves the steady-state equation by solving a generalized eigenvalue problem by means of a Krylov-Schur method. One of the main advantages of the method is the capability to calculate multiple eigenfunctions. The Discrete Ordinates methodology is used for the angular discretization, which uses a simple formulation involving the angles and direction cosines. The spatial discretization with Finite Difference Method is selected for its simplicity. The method is validated with several one-dimensional benchmark problems and four two dimensional benchmark problems. The results show good agreement with respect to the reference results for all the cases studied.

The layered oxychalcogenides BiCuOCh (Ch = S, Se, and Te) have gained extensive attention due to their low lattice thermal conductivity, moderate Seebeck coefficient, and tunable electrical conductivity. However, the thermoelectric properties of their Ag-based isomorphic compounds are still unclear. Here, by means of first‐principles calculations and Boltzmann transport theory, we identify that three materials exhibit intrinsically low lattice thermal conductivity. Because of large unit volumes and relatively low sound velocities, the lattice thermal conductivities for BiAgOS, BiAgOSe, and BiAgOTe are only 0.63, 0.58, and 0.49 W/mK, respectively. Combined with the analysis of electrical transport measurements results, the p-type BiAgOSe along a-direction shows preferable thermoelectric character with the maximum ZT value of 2.38 at 300 K. Besides, the ZT values for p-type BiAgOS and BiAgOTe at the same temperature along a-direction could reach to 1.75 and 1.90. Our results reveal that the family of oxychalcogenides BiAgOCh is potential p-type thermoelectric material. Especially, although n-type BiAgOCh cannot be a comparable thermoelectric material (ZT = 0.04-0.71), our results imply that optimum carrier concentration for n-type BiAgOS and BiAgOSe could be proved as an effective regulation strategy for relatively large ZT value. This is mainly due to the fact that ZT value has more than one extreme points from low carrier concentration (1 x 1018 cm−3) to high carrier concentration (1 x 1022 cm−3). Furthermore, this finding opens a new avenue for these oxychalcogenides compounds and significantly accelerates the process of the applications in oxides as potential high temperature thermoelectric materials.

The layered oxychalcogenides BiCuOCh (Ch = S, Se, and Te) have gained extensive attention due to their low lattice thermal conductivity, moderate Seebeck coefficient, and tunable electrical conductivity. However, the thermoelectric properties of their Ag-based isomorphic compounds are still unclear. Here, by means of first‐principles calculations and Boltzmann transport theory, we identify that three materials exhibit intrinsically low lattice thermal conductivity. Because of large unit volumes and relatively low sound velocities, the lattice thermal conductivities for BiAgOS, BiAgOSe, and BiAgOTe are only 0.63, 0.58, and 0.49 W/mK, respectively. Combined with the analysis of electrical transport measurements results, the p-type BiAgOSe along a-direction shows preferable thermoelectric character with the maximum ZT value of 2.38 at 300 K. Besides, the ZT values for p-type BiAgOS and BiAgOTe at the same temperature along a-direction could reach to 1.75 and 1.90. Our results reveal that the family of oxychalcogenides BiAgOCh is potential p-type thermoelectric material. Especially, although n-type BiAgOCh cannot be a comparable thermoelectric material (ZT = 0.04-0.71), our results imply that optimum carrier concentration for n-type BiAgOS and BiAgOSe could be proved as an effective regulation strategy for relatively large ZT value. This is mainly due to the fact that ZT value has more than one extreme points from low carrier concentration (1 x 1018 cm−3) to high carrier concentration (1 x 1022 cm−3). Furthermore, this finding opens a new avenue for these oxychalcogenides compounds and significantly accelerates the process of the applications in oxides as potential high temperature thermoelectric materials.

The colloidal self-assembly of plasmonic gold nanoparticles (AuNPs) is of interest to utilize the plasmonic coupling effects that arise between nanoparticles. The enhanced properties of anisotropic AuNPs make them particularly attractive in self-assemblies. Herein, a literature study into the different strategies used to obtain self-assemblies of AuNPs using molecular linkers is presented. The use of nanospheres (AuNS) and nanorods (AuNRs) were mainly reviewed. Thereafter, two different nanobipyramids (AuBPs) were investigated for use in self-assemblies. The concentration of cetyltrimethylammonium bromide (CTAB), which coats the AuNP surface, was manipulated to study the stability of the AuNPs. A stable, meta-stable and non-stable region were identified for the nanoparticles. At low CTAB levels, the AuNPs preferentially assemble end-to-end. The addition of L-cysteine to stable AuNP dispersion induced end-to-end assembly, showing promise as a molecular linker for AuBPs. The addition of excess CTAB stabilized the assemblies over time. The kinetic behaviour of the two AuBPs differed, suggesting the effect of the AuNP shape on the self-assembly kinetics. This study provides a starting point for the development of a robust self-assembly strategy for anisotropic AuNPs by using L-cysteine as a molecular linker., Den kolloidala självsammansättningen av ytplasmoniska guld nanopartiklar (AuNPs) är av intresse för att utnyttja de plasmoniska kopplingseffekterna som uppstår mellan nanopartiklar. De fördelaktiga egenskaperna hos anisotropa AuNP gör dem särskilt intressanta för självsammansättningar. En litteraturstudie har gjorts på de olika strategier som används för att erhålla självsammansättningar av AuNPs med hjälp av molekylära länkar. Användningen av nanosfärer (AuNS) och nanostavar (AuNRs) i självsammansättningar undesöktes huvudsakligen. Därefter undersöktes två olika nanobipyramider (AuBPs) för användning i självsammansättningar. Koncentrationen av cetyltrimetylammonium bromid (CTAB), som täcker AuNP-ytan, manipulerades för att undersöka AuNPs stabilitet. En stabil, meta-stabil och instabil region identifierades för nanopartiklarna. Vid låga CTAB-nivåer sammansätts AuNPs ände-mot-ände. Tillsatsen av L-cystein till stabila AuNP dispersioner inducerade sammansättningar ände-mot-ände, vilket visar L-cysteins potential som en molekylär länk för AuBPs. Tillsatsen av en stor mängd CTAB stabiliserade självsammansättningarna för en längre tid. Det kinetiska beteendet hos de två AuBPs skilde sig, vilket tyder på effekten av AuNP-formen på den självsammansättningskinetiken. Denna studie erbjuder en startpunkt för utvecklingen av en robust självsammansättningstrategi för anisotropa AuNPs genom att använda L-cystein som en molekylär länk.

In the present paper, we analyze the well-known 2+1 dimensional black holes (assuming a non-vanishing cosmological constant) in light of the gravitational decoupling by the minimal geometric deformation approach. To illustrate our results, we consider the BTZ geometry as the seed solution to generate new anisotropic ones. To complement the study, the curvature scalars and the energy conditions are analyzed.

Cardiovascular disease has caused 3.9 million deaths in Europe and over 1.8 million deaths in the European Union, which accounts for 45\% of all deaths in Europe and 37\% of all death in the European Union in 2017. Cardiovascular disease is mainly caused by atherosclerosis. Atherosclerosis is a kind of disease where the inside of the artery gets narrow due to the build-up of plaque. Plaque is an abnormal accumulation of material in the inner layer of the arterial wall. A swelling can be formed by the accumulated material. The swelling may intrude into the channel of the artery wall, which will make the channel get narrower and restrict blood flow. Based on current medical technology, images of the plaques can be taken. However, there are no efficient simulation tools for plaque rupture. In order to set up sufficient simulation tools, a good representation of the material behaviour and the progression of the failure is needed. There are material models for the arterial wall accounting for large deformations (hyperelasticity) and anisotropy in the material response. And, there are also failure models. However, the material models and the failure models have not been combined. In this thesis, three material models and one failure model are included. The three material models are Neo-Hookean material model and two anisotropic models developed for arterial wall tissue developed by Holzapfel and Gasser. They are combined with anisotropic damage model to obtain three new constitutive models for failure of hyperelastic material. After the three constitutive models are set up, a parameter study is performed to explore the material properties of the new constitutive models. Verification of the material models is also included. Finally, the performance of the model is demonstrated with failure analyses on different geometries: a simple plane, a bar, a plane with an imperfection and a plane with a rectangular hole in the middle.

Recently, additive manufacturing (AM), or "3D printing," is expanding into civil infrastructure applications, particularly cementitious materials. To ensure the safety, health, and welfare of the public, quality assurance and quality control (QA/QC) methods via standardized testing procedures are of the upmost importance. However, QA/QC methods for these applications have yet to be established. This thesis aims to implement existing ASTM standards to characterize additive manufactured cementitious composites and to gather better information on how to tackle the challenges that are inherent when printing with cementitious materials. In this work, fresh mix properties and hardened concrete properties were investigated using current ASTM standards as a starting point for applying or adapting them for AM applications. Specifically, this project applied existing ASTM standards for fresh mix mortars to measure setting time, flow, and early compressive strength as qualitative indicators of printability, pumpability, and buildability. The fresh mix properties were investigated for 12 different mortar mixes to demonstrate the effect that moisture content, absorption, and sand type can have on these fresh mix properties. The results for setting time and compressive strength demonstrated that there was less variability in the properties when the moisture condition of the aggregate was measured and accounted. Flow was shown to be strongly influenced by the sand type. Additively manufactured mortars were used to print a box in a layer-by-layer process. To evaluate the effect of layering on the flexural strength, three-point bending tests were implemented using four different loading orientations to explore the anisotropic mechanical properties. The observed anisotropic behavior was corroborated with stereo-digital image correlation data showing the stress-strain and load-deflection relationships. Two orientations (A and B) demonstrated brittle behavior while the other two orient