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This paper reviews some of the modelling and experimental techniques recently employed by the authors for the analysis of the macro- and mesoscopic behaviour of polycrystalline aggregates. A joined-up approach is used for assessing the deformation behaviour of polycrystalline materials at the macroscopic and grain levels, based on combining modelling using the crystal plasticity finite element (CPFE) method with experimental characterization by in situ loading and continuous lattice strain measurement by diffraction. The complementarity of the two methodologies is emphasized, as it helps to improve understanding of the physics underlying inelastic deformation, damage mechanisms, and fatigue crack initiation. The proposed approach is part of the attempt to develop a general framework that will enable reliable and accurate determination of the inhomogeneous fields of plastic strain, the regions of localized plasticity, and intergranular residual stresses. Examples are given of microscopically calibrated CPFE simulations being used to match the experimentally observed evolution of lattice stresses and strains in advanced structural alloys of industrial interest. [ABSTRACT FROM AUTHOR]

Abstract: High-resolution spectroscopy of the rare earth ions in transparent ceramics of garnets and sesquioxides produced by solid-state synthesis indicate that the variety, nature and structure of the centers formed by the doping ions, their quantum states (energy levels, transition probabilities) and interionic interactions as well as the distribution of the doping ions at the available lattice sites is similar to those of the corresponding single crystals. Moreover, the increased compositional versatility of ceramics enables tailoring of new or improved laser materials. It is inferred that from spectroscopic point of view, the transparent polycrystalline ceramics can substitute the single crystal and extend their capabilities. [Copyright &y& Elsevier]

Si-doped GaN films in polycrystalline form were deposited on quartz substrates at deposition temperatures ranging from 300-623 K using r.f. sputtering technique. Electrical, optical and microstructural properties were studied for these films. It was observed that films deposited at room temperature contained mainly hexagonal gallium nitride (h-GaN) while films deposited at 623 K were predominantly cubic (c-GaN) in nature. The films deposited at intermediate temperatures were found to contain both the hexagonal and cubic phases of GaN. Studies on the variation of conductivity with temperature indicated Mott's hopping for films containing c-GaN while Efros and Shklovskii (E-S) hopping within the Coulomb gap was found to dominate the carrier transport mechanism in the films containing h-GaN. A crossover from Mott's hopping to E-S hopping in the 'soft' Coulomb gap was noticed with lowering of temperature for films containing mixed phases of GaN. The relative intensity of the PL peak at ∼ 2·73 eV to that for peak at ∼ 3·11 eV appearing due to transitions from deep donor to valence band or shallow acceptors decreased significantly at higher temperature. Variation of band gap showed a bowing behaviour with the amount of cubic phase present in the films. [ABSTRACT FROM AUTHOR]

Abstract: Property closures delineate the complete set of theoretically feasible combinations of macroscale (homogenized) properties in a given material system. A novel spectral framework called microstructure sensitive design (MSD) was recently formulated and demonstrated to be capable of delineating elastic–plastic property closures in a number of composite material systems. In particular, it was successfully applied to cubic polycrystals, where it was assumed that the crystallographic texture had a dominant influence on the macroscale properties of interest. Application of these procedures to hexagonal polycrystals posed significant computational difficulties, because of the need to represent the texture in the hcp polycrystals in a much larger number of dimensions in the Fourier space compared with what was needed for the cubic polycrystals. This paper reports new computational schemes for delineating elastic–plastic closures for hcp polycrystals using the spectral framework of MSD. The primary focus of this paper continues to be on the influence of the crystallographic texture (in the hcp polycrystal) on the components of the macroscale anisotropic elastic stiffness, macroscale anisotropic tensile yield strength, and the macroscale R ratios (ratio of the transverse strains in tensile deformation mode) exhibited by the material. [Copyright &y& Elsevier]

Abstract: The elastic–plastic behaviour of particle-reinforced metal matrix composites undergoing ductile damage is modelled using a two-level micro-structural approach. The considered heterogeneous material is a polycrystal containing intra-crystalline elastic particles. Ductile damage is initiated by the matrix/particle interface debonding and the subsequent voids growth with plastic straining of the crystalline matrix. Homogenization techniques are used twice: first at mesoscale to derive the equivalent grain behaviour and then to obtain the macroscopic behaviour of the material. Plastic deformation of the crystalline matrix is due to crystallographic gliding on geometrically well-defined slip systems. The associative plastic flow rule and the hardening law are described on the slip system level. The evolution of micro-voids volume fraction is related to the plastic strain. The elastic–plastic stress–strain response of particle composite is investigated. Predictions of the proposed model are compared to experimental data to illustrate the capability of the suggested method to represent material behaviour. Furthermore, specific aspects such as the stress triaxiality and yield surfaces are discussed. [Copyright &y& Elsevier]

The wide-angle scattering of X-rays (WAXS) by anisotropic powders of nano-layered crystallites (nano-stacks) is addressed. Assuming that the orientation distribution probability function f of the nano-stacks only depends on the deviation of the crystallites' orientation from a fixed reference direction, a relation providing f from the dependence of a given diffraction peak's amplitude on the azimuthal angle is derived. The method is applied to two systems of sodium fluorohectorite (NaFH) clay particles, using synchrotron radiation and a WAXS setup with a two-dimensional detector. In the first system, which consists of dry-pressed NaFH samples, the orientation distribution probability function corresponds to a classical uniaxial nematic order. The second system is observed in bundles of polarized NaFH particles in silicon oil; in this case, the nano-stacks have their directors, on average, in a plane normal to the reference direction, and f is a function of the angle between a nano-stack's director and that of the plane. In both cases, a suitable Maier–Saupe function is obtained for the distributions, and the reference direction is determined with respect to the laboratory frame. The method only requires one scattering image. Consistency can be checked by determining the orientation distribution from several diffraction peaks independently. [ABSTRACT FROM AUTHOR]

A salient manifestation of anisotropy in the mechanical response of polycrystalline materials is the inhomogeneous partitioning of elastic strains over the aggregate. For bulk samples, the distributions of these intergranular strains are expected to have a strong functional dependence on grain orientations. It is then useful to formulate a mean lattice strain distribution function (LSDF) over the orientation space, which serves to characterize the micromechanical state of the aggregate. Orientation-dependent intergranular stresses may be recovered from the LSDF via a constitutive assumption, such as anisotropic linear elasticity. While the LSDF may be determined directly from simulation data, its experimental determination relies on solving an inverse problem that is similar in character to the fundamental problem of texture analysis. In this paper, a versatile and robust direct method for determining an LSDF from strain pole figures is presented. The effectiveness of this method is demonstrated using synthetic strain pole figures from a model LSDF obtained from the simulated uniaxial deformation of a 1000-crystal aggregate. [ABSTRACT FROM AUTHOR]

Abstract: Herein we derive an expression for direct determination of the geometric autocorrelation function W of a polycrystalline material from images of its grain boundary network (e.g., those delivered by orientation imaging microscopy). We also obtain an identity that relates the mean linear intercept function to a directional derivative of the geometric autocorrelation function. These formulae were applied to examine whether a widely-used formula for W, particularly in theoretical studies of attenuation of elastic waves in polycrystalline media, would be valid for the grain boundary structure of a commercial aluminum alloy. The conclusion was negative. [Copyright &y& Elsevier]

The physics of polycrystalline materials is described via microscopic processes such as grain boundary migration, grain growth, grain rotation, polygonization (the bending and breaking of crystallites) and evolution of dislocation density. The importance of taking these processes into account lies in their influence on the macroscopic mechanical behaviour of the material. Constitutive equations to describe such phenomena have been proposed in the literature. The main result of this paper is to give a general and thermodynamically consistent approach for such constitutive equations. The framework of the Theory of Mixtures with Continuous Diversity (TMCD) is used. The inclusion of both orientation and grain-size distributions is presented in this paper for the first time. Their introduction requires the formulation of a new and general constitutive theory that is, therefore, given. The method of Lagrange multipliers used in the context of the entropy principle (Liu, Arch. Rat. Mech. Anal. 46, 131–148 (1972)) provides the restrictions of the second law of thermodynamics on the constitutive equations. The success of this work is that all the main results present in the literature can be incorporated in this framework. [ABSTRACT FROM AUTHOR]

Abstract: The dependence of shear yield strength on grain size is analyzed using discrete dislocation dynamics. Plastic deformation is modeled through the motion of edge dislocations in an elastic solid. The lattice resistance to dislocation motion, dislocation nucleation, dislocation interaction with obstacles and dislocation annihilation are incorporated through a set of constitutive rules. Grain boundaries are modeled as impenetrable to dislocations. Single slip is assumed within each grain and a checkerboard-like arrangement of grains is used as a unit cell for the polycrystal. Doubly-periodic pure shear calculations are carried out for planar polycrystals with grain sizes in the range m and for two values of initial dislocation source density that differ by an order of magnitude. The offset flow strength varies with grain size, d, as , with or , depending on source density. The value of the offset flow strength is higher for the low source density polycrystal. Furthermore, for each initial source density, the flow strength was found to scale roughly with dislocation density. [Copyright &y& Elsevier]

Abstract: Three-dimensional (3D) measurements of strain tensor distributions with subgrain resolution are now possible due to an emerging class of instrumentation: the 3D X-ray crystal microscopes. These instruments combine ultra-intense synchrotron X-ray sources and advanced X-ray optics to probe polycrystalline materials with submicron spatial resolution. By employing polychromatic X-ray beams and a virtual pinhole camera method, called differential aperture microscopy, 3D distributions of the local crystalline phase, orientation (local texture) and elastic and plastic strain tensor distributions can be measured with resolution below the grain size of most materials. The elastic strain tensor elements can typically be determined with uncertainties less than 100ppm in brittle materials. Orientations can be quantified to ∼0.01° and the local unpaired dislocation density can be measured in ductile materials. Efforts are underway to improve the spatial resolution and increase the depth probed. Because the 3D X-ray crystal microscope is a penetrating nondestructive tool, it is ideal for studies of mesoscale structural evolution in materials. The unprecedented information that can be obtained with this new class of instrumentation is certain to advance our understanding of the materials physics underpinning the behavior of polycrystalline materials. [Copyright &y& Elsevier]

This study deals with modelling of the elastoplastic behaviour of a polycrystalline material, subjected to complex loading programmes, using a self-consistent scheme based on scale transition techniques. The influence of microstructure evolution on the elastoplastic response of the material is analysed. A brief introduction to the self-consistent modelling is presented. The comparison of the numerical results with the experimental data available from literature reveals a good agreement between the calculated and measured evolution of yield surface. From the three parameters describing the internal structure of the material, the grain shape evolution is neglected in this study. The remaining two are internal stresses and crystallographic texture. The influence of these parameters on subsequent yield surfaces is analysed. When compared with the second-order residual stresses, the role of crystallographic texture in hardening of polycrystals appears to be insignificant. The influence of the intragranular microstructure, or third-order internal stresses, is addressed indirectly by appropriate simulations involving the hardening matrix of individual crystals. [Copyright &y& Elsevier]

An analytical model providing simultaneous, self-consistent representations of the temperature and porosity dependence of the elastic and bulk moduli of polycrystalline ceramics is applied to data compiled from the literature for 24 oxide ceramics. [ABSTRACT FROM AUTHOR]

In this paper, we present an isothermal Monte Carlo (MC) algorithm that can be employed to simulate the grain growth in polycrystalline iron during sintering. The evolution of grain structure was simulated using a three-dimensional (3D) MC model of grain growth. Both the average grain size and the grain size distribution are calculated. The distribution of number of sides of grains and grain edges from this simulation is in good agreement with the experimental results. This paper also deals with oriented and anisotropic grain growth as well. A considerable number of input parameters in the model allow simulation of a wide variety of conditions. [Copyright &y& Elsevier]

Validation of continuum crystal plasticity models for polycrystalline materials requires experiments with sub-grain scale resolution, performed on materials with realistically small grain sizes. To date only limited experiments have been performed to investigate displacement fields with resolution well below the grain scale over a wide field for polycrystals with realistic grain sizes. This paper explores high-resolution in-plane material stretch and rotation fields measured at the sub-grain scale for ensembles of 10–20 grains in 70 μm grain-size OFHC Cu. Using a novel photolithographic technique, a series of micron-scale grids were deposited onto the surface specimens that were subsequently subjected to compression or torsion to effective strains up to unity. The resulting grid patterns for compression exhibit a tendency toward localization of stretch and rotation fields, with larger grains less highly deformed. For the case of shear, there is a reduced tendency towards microstructural scale localization of the in-plane stretch and rotation fields. [Copyright &y& Elsevier]

A theoretical model is suggested which describes changes of grain boundary misorientation parameters in plastically deformed polycrystalline and nanocrystalline materials. In the framework of the model, the changes occur via grain boundary disclination motion associated with emission of dislocation pairs from grain boundaries into adjacent grain interiors. Energetic characteristics of the disclination motion in question are calculated. [Copyright &y& Elsevier]

Indentation and sliding experiments were conducted on some fcc, bcc, and hcp structured, single crystal (copper, aluminum, iron, zinc, and cadmium) and polycrystalline (iron, tin, aluminum oxide and magnesium meta-aluminate) materials. Hard indenters (steel, sapphire, and diamond) were used to investigate the anisotropic behavior of these materials in indentation and sliding. A conventional microhardness tester modified to enable sliding of the specimens past the indenter and to incorporate the means for the measurement of frictional force using strain gages was used in this investigation. Optical microscopy (including interference contrast) was used to characterize the specimens after indentation/sliding. An attempt was made to correlate the gross macroscopic behavior in terms of microscopic events. The results of this study show that indentation and sliding on a microscopic scale, such as with a hard indenter can reveal unique characteristics for both single crystal and polycrystalline materials. [Copyright &y& Elsevier]

In the machining of mirror-like surfaces, a typical cutting depth of a few micrometers is common. With such a small depth of cut, chip formation takes place within individual grains of polycrystalline materials. In this article, orthogonal cutting of single copper crystals was performed in order to investigate the dependency of cutting deformation and surface quality on the crystallographic orientation of the substrate material. The experimental results show that the crystallographic orientation of the workpiece exerts a significant influence on the shear angle and the machined surface roughness. Cutting force variation with crystallographic orientation was analyzed on the basis of a microplasticity model. The trend in the variation of theoretical values of an effective Taylor factor (the shear strength) compares well with that of published experimental data on cutting forces. [ABSTRACT FROM AUTHOR]

• An empirical equation was proposed to estimate the level of misorientation dispersion at the grain scale as a function of grain size and plastic global strain. • {100} and {110} orientations, with respect to tensile direction, exhibited the largest and smallest tendency for local orientation change, respectively. • Large grains exhibited a greater misorientation level than the small grains, where the difference became more pronounced for larger grains with increased strain. • The misorientation level is sensitive to the strain path, as the misorientation was higher for the interrupted tests compared with the monotonic tests. The correlation between plastic strain and crystallographic misorientation, grain size, grain orientation, distance from grain boundary, and loading history were investigated experimentally and numerically for body-centered-cubic (BCC) polycrystalline microstructures based on a misorientation deviation (MD) approach. Nine monotonic tensile experiments were performed on two BCC titanium alloys inside a scanning electron microscope (SEM). The influence of reference orientation was explored both at the grain scale and at the mesoscale using electron backscattered diffraction (EBSD). The correlation between global plastic strain and the MD was quantified. The tendency for orientation change was quantified as a function of plastic strain and grain orientation for three crystallographic orientations (i.e., [100], [110], and [111]) with respect to tensile direction. The subpopulation of small grains exhibited a lower level of misorientation dispersion compared with larger grains, and this discrepancy became more pronounced at higher strains. An empirical equation was proposed to estimate the level of misorientation dispersion for individual grains as a function of grain size and global plastic strain level. Two interrupted in-situ SEM experiments were performed, and this resulted in a significantly increased misorientation compared with uninterrupted tests performed to similar plastic strain levels. [ABSTRACT FROM AUTHOR]

One of the most important aims of grain boundary modeling is to predict the evolution of a large collection of grains in phenomena such as abnormal grain growth, coupled grain boundary motion, and recrystallization that occur under extreme thermomechanical loads. A unified framework to study the coevolution of grain boundaries with bulk plasticity has recently been developed by [1] , which is based on modeling grain boundaries as continuum dislocations governed by an energy based on the Kobayashi–Warren–Carter (KWC) model [2,3]. While the resulting unified model demonstrates coupled grain boundary motion and polygonization (seen in recrystallization), it is restricted to grain boundary energies of the Read–Shockley type, which applies only to small misorientation angles. In addition, the implementation of the unified model using finite elements inherits the computational challenges of the KWC model that originate from the singular diffusive nature of its governing equations. The main goal of this study is to generalize the KWC functional to grain boundary energies beyond the Read–Shockley-type that respect the bicrystallography of grain boundaries. The computational challenges of the KWC model are addressed by developing a thresholding method that relies on a primal dual algorithm and the fast marching method, resulting in an O (N log N) algorithm, where N is the number of grid points. We validate the model by demonstrating the Herring angle and the von Neumann–Mullins relations, followed by a study of the grain microstructure evolution in a two-dimensional face-centered cubic copper polycrystal with crystal symmetry-invariant grain boundary energy data obtained from the covariance grain boundary model of [4,5]. [ABSTRACT FROM AUTHOR]

A three-dimensional framework for low-cycle fatigue analysis of polycrystalline aggregates is proposed in this work. First, a cohesive law coupling plasticity and damage is developed for modelling cycle-by-cycle degradation of material interfaces up to complete de-cohesion and failure. The law may model both quasi-static degradation under increasing monotonic load and degradation under cyclic loading, through a coupled plasticity-damage model whose activation and flow rules are formulated in a thermodynamically consistent framework. The proposed interface laws have been then implemented and coupled with a multi-region boundary element formulation, with the aim of analysing low-cycle intergranular fatigue in polycrystalline aggregates. The boundary element formulation allows expressing the micro-mechanical problem in terms of grain-boundary displacements and tractions only, which are the quantities directly entering the cohesive laws, thus simplifying the coupling of the two tools. After assessing the response of an individual interface, to both quasi-static and cyclic loads, the coupled framework has been employed for the computational investigation of low-cycle degradation in fully-3D and pseudo-3D, or 2D columnar, polycrystalline aggregates, assuming that the degradation process remains confined in the intergranular regions. The discussed results show the potential of the developed formulation for multiscale materials modelling , which may find future application in the multiscale design of engineering structures subjected to complex loads and degradation processes, and for computational micromechanics , which may find direct application in the design and analysis of micro-electromechanical systems (MEMS). [Display omitted] • A micromechanical framework for polycrystalline low-cycle fatigue is presented. • Original elastic–plastic cohesive laws with hysteresis are developed and tested. • The proposed cohesive laws are used in conjunction with a BEM multi-region method. • The problem is expressed in terms of intergranular displacements and tractions only. • The method can be used in multiscale applications and for MEMS analysis & design. [ABSTRACT FROM AUTHOR]

For large-grained samples it is advantageous to perform pairs of neutron diffraction measurements at the same spatial location but rotated 180° around the geometric centre of the gauge volume as a means of minimizing the scatter coming from the random positioning of grains within the gauge volume. [ABSTRACT FROM AUTHOR]

Industrial inspection protocols are qualified using mock-ups manufactured according to the same procedure as the plant part. For coarse-grained castings, known for their low inspectability, relying on mock-ups becomes particularly challenging owing to the variability of grain properties among components. Consequently, there is a keen interest in the capability to verify whether the grain size of the component under test matches the qualification specification in-situ. This paper investigates the potential of an attenuation measurement for assessing the ultrasonic inspectability of coarse-grained components using qualified procedures in a practical setting. The experimental part of the study focuses on an industrial Inconel 600 mock-up with spatially varying attenuation, measured across the entire sample in an immersion tank. Three zones with distinctly different attenuations were examined using metallography, which allowed for calculating classical grain size histograms and two-point correlation functions. For one of the zones, we synthesised the microstructure with the same statistical properties numerically and simulated the propagation of ultrasound using a grain-scale finite element model. The results showed good agreement with the experiment, and lead to several suggestions for the reasons for the discrepancy, the varying grain size statistics being the most likely. A parametric study, which followed, depicted the effect of the mean and standard deviation-to-mean ratio of the log-normal grain size distribution on the attenuation of ultrasound and its frequency dependence. Most notably, we demonstrated the known non-uniqueness of the relationship between the log-normal grain size distribution parameters and the attenuation. We suggested that the correlation length calculated from a single exponential fit to the two-point correlation function is a more robust metric describing grain statistics for this context, which can be obtained from attenuation. The correlation lengths estimated from measured attenuation using the second-order approximation model for the three zones of the studied mock-up yielded results of acceptable accuracy. We concluded that this metric could replace the average grain size in practical settings, as it retains more statistical information than the mean grain size and allows for linking measurements to the established theoretical attenuation models which this paper demonstrates. • Local grain size in a casting is estimated from ultrasonic attenuation. • Based on measurements and material examination of an industrial mock-up. • The relationship between the grain size distribution and attenuation is non-unique. • Correlation length is a robust metric that can be determined from attenuation. • Correlation lengths estimated from ultrasonic measurements agree with metallography. [ABSTRACT FROM AUTHOR]

This paper presents a multiscale approach to model the dynamic transition between macro, micro, and homogenized atomistic scales in 2D polycrystalline materials. At the macroscale, the material is assumed as an isotropic homogeneous medium. The material at the microscale, in contrast, is characterized by anisotropic grains with stochastic morphologies and random crystalline orientations. The Boundary Element Method (BEM) is used to model both macro and micro scales using isotropic and anisotropic formulations, respectively. To connect both scales, the macro transient responses at internal points are prescribed as boundary conditions to the microscale analysis. The mechanical behavior at the interfaces between grain boundaries is assessed using Cohesive Interface Elements (CIEs). Based on the Multiscale Cohesive Zone Model (MCZM), this approach transfers the homogenized strain energy evaluated in the CIE during the microscale analysis to an atomistic arrangement. In order to define a failure criterion from the atomistic interpretation, the extended Finnis–Sinclair potential is applied to describe the interactions between atoms. Finally, we present some examples of intergranular crack propagation resulting from the rupture of atomic bonds due to the interatomic forces. [ABSTRACT FROM AUTHOR]

• Processing temperature impact on inner structure, chemical defects and thermal conductivity of ZnO thin films. • The thermal conductivity of oxygen-rich layers lower in comparison to zinc-rich samples. • Determination of boundary thermal resistance and its correlation with chemical defects. • Heat transfer mechanisms in low temperature ALD ZnO thin films. Two sets of ZnO thin films grown by atomic layer deposition method were investigated to analyse the correlation between morphology, chemical defects and thermal properties. This analysis became possible by measuring series of similarly thick wurtzite ZnO films synthesized using identical number of deposition cycles at two temperatures – 100 °C and 200 °C. By comparing these sample series, exhibiting the thickness variations from 12 to 118 nm, we observed several prominent correlations for the thermal properties as measured by high-resolution scanning thermal microscopy at room temperature. Specifically, comparing thinnest samples in the series, a lower thermal conductivity was revealed in samples grown at 100 °C and these variations were interpreted in terms of changing populations of native donors, affecting the free carrier concentration and, as such, the thermal conductivity. Further, the increase in thickness for the samples grown at 200 °C was accompanied with a continuous shift to Zn-rich conditions and the corresponding increase in the thermal conductivity, specifically from 0.28 Wm−1 K−1 to 2.81 Wm−1 K−1. As such, we have decoupled the thickness effect on the thermal conductivity from the rest of the phenomena, explaining the thermal transport in terms of the bulk thermal contributions within the grains combined with additional thermal resistance introduced by the grain boundaries. [ABSTRACT FROM AUTHOR]

Anisotropic 1-site and 2-site self-consistent models are developed to describe the elastic-viscoplastic behavior of polycrystalline materials deformed to finite strains on the basis of rate-dependent crystallographic slip and a generalized Hill-Hutchinson self-consistent approach. The choice of rate-dependent constitutive law at single crystal level implemented in the models is discussed through fitting experimental data and calibrating viscous parameters. It is found that drag-stress type Norton law works well for the 1-site elastic-viscoplastic self-consistent (EVPSC) model while threshold stress type Norton law is suitable for the 2-site EVPSC model to assure that the viscoplastic inter-granular interaction is realistic. Both models have been verified by thoroughly fitting experimental data in literatures. For the 1-site EVPSC model, selected experimental data covers both macroscopic and microscopic mechanical responses of steels during deformation with a large range of strain rate from the quasi-static (10 − 4 s − 1 ) to the dynamic (~ 10 4 s − 1 ). For the 2-site EVPSC model, in situ neutron diffraction data of nickel-based superalloys with various microstructures was fitted. Both models generally fit the experimental data well. A comparison between the EVPSC and elastic-plastic self-consistent (EPSC) models on the prediction of lattice strains has also been made for both the 1-site and 2-site cases, which verifies the predictability on lattice strains of the newly developed EVPSC models. A validation of the homogenization approach for the EVPSC modeling has been performed, which confirms that the proposed EVPSC models are applicable for cubic structure materials with finite deformations. Our formulation of EVPSC modeling developed in this work shines a spotlight on the way of developing a multi-functional self-consistent model to predict both macroscopic and microscopic deformation behaviors of various polycrystalline materials under different loading rates of 10 − 4 s − 1 ~ 10 4 s − 1 . • General finite strain elastic-viscoplastic self-consistent models are developed. • Predictions of the 1-site model fit the dynamic and static tests of steels well. • Predictions of the 2-site model adequately fit the experimental data of superalloys. • Simulated transverse lattice strains are sensitive to the time dependent response. • The homogenization approach for the EVPSC modeling is validated. [ABSTRACT FROM AUTHOR]

This research work presents, within a unified and wave oriented variational framework, systematic development of upwind numerical fluxes for the space discontinuous Galerkin methods to model elastic wave propagation in multidimensional anisotropic media with discontinuous material properties. Both first-order velocity–stress and velocity–strain wave formulations are considered. The proposed approach allows the derivation of upwind numerical fluxes in a well structured and hierarchical way according to the degree of inhomogeneity across a physical interface. The numerical fluxes that are exact solutions of a relevant Riemann problem defined at a physical interface are obtained. The developed explicit and intrinsic tensorial expressions of upwind numerical fluxes in multidimensional case allow a better understanding and analysis of the physical meaning of involved terms. As numerical applications, an example with a physical interface separating two materials, one anisotropic and the other isotropic, and an example of polycrystalline material that presents a particular case with a larger number of physical interfaces, are considered. The proposed numerical fluxes are numerically investigated and validated. • A systematic development of upwind fluxes for the space dG method is proposed. • Upwind fluxes are formulated in explicit and tensorial expressions. • The most general case of physical interfaces between anisotropic media is treated. • Defining appropriate Riemann problem results into physically sound fluxes. • Numerical validation is made by considering polycrystalline materials. [ABSTRACT FROM AUTHOR]