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Two-dimensional 3 × 3 array representative volume element (RVE) models, using finite element analysis (FEA), have been employed to predict the elastic moduli (Ec) of polypropylene (PP)/organoclay nanocomposites in terms of clay contents, clay aspect ratios and their dispersion patterns. Three-phase RVE models incorporating the interphase between clay platelets and the PP matrix demonstrate significant modulus enhancement in the exfoliated nanocomposites. The interphase properties have less impact on the moduli of exfoliated nanocomposites while those of intercalated nanocomposites are quite independent of clay dispersion patterns. The numerical results are finally compared with composites theories and experimental data for validity.

The acoustic cloak is an important device, which can cloak an object from the detecting of sonar. Based on the concepts of complementary media and nonlinear coordination transformation, the generalized expressions for material parameters of the complementary medium-assisted external acoustic cloak with N-sided regular polygonal cross section are derived. It can cloak the object with arbitrary shape outside the cloaking domain, as long as an “antiobject” is embedded in the complementary layer. The external cloaking effect has been verified by full-wave simulation.

Electronic structure and optical properties calculations of NiSi2 were carried out using the Full-Potential Linearized Augmented Plane Waves (FLAPW) method, within the Density Functional Theory (DFT) with the Local Density Approximation (LDA). Band structure and total and projected density of states (DOS) are calculated as well as the theoretical Electron Energy-Loss (EEL) Spectrum, utilizing experimental lattice parameters. Our theoretical EELS results are in agreement with recent experimental findings, indicating that the main peak corresponds to a plasmon. Additional peaks in our calculations are identified as interband transitions (at 2.67 eV, 4.77 eV and 6.1 eV) associated to transitions between Ni d and Si p states, and low magnitude plasmons (at 1.3 eV and 4.02 eV).

In this investigation, we focus on the melting of elements Cu, Pd as well as Cux–Pd1−x random alloys. The thermodynamic properties such as melting temperature, isobaric heat capacity and lattice thermal expansion coefficient were calculated as a function of pressure in the range of 0–100 GPa. Moreover, the temperature dependence of energy, order parameter, volume, and density were calculated in various pressures. These calculations were performed by molecular dynamics simulation technique in NPT ensemble. The results showed melting temperature increase upon increasing pressure. Furthermore, isobaric heat capacity and lattice thermal expansion decreased with increasing pressure. These variations were found to be nonlinear approximating a constant value at higher pressures. Our results are in reasonable agreement with the experimental data where they are available.

A cellular automaton algorithm with probabilistic cell switches is employed in the simulation of dynamic discontinuous recrystallization. Recrystallization kinetics are formulated on a microlevel where, once nucleated, new grains grow under the driving pressure available from the competing processes of stored energy minimization and boundary energy reduction. Simulations of the microstructural changes in pure Cu under hot compression are performed where the influence of different thermal conditions are studied. The model is shown to capture both the microstructural evolution in terms of grain size and grain shape changes and also the macroscopic flow stress behavior of the material. The latter gives the expected transition from single- to multiple-peak serrated flow with increasing temperature. Further, the effects on macroscopic flow stress by varying the initial grain size is analyzed and the model is found to replicate the shift towards more serrated flow as the initial grain size is reduced. Conversely, the flow stress is stabilized by larger initial grain sizes. The extent of recrystallization as obtained from simulations are compared to classical JMAK theory and proper agreement with theory is established. In addition, by tracing the strain state during the simulations, a post-processing step is devised to obtain the macroscopic deformation of the cellular automaton domain, giving the expected deformation of the equiaxed recrystallized grains due to the macroscopic compression.

A simplified model for calcium leaching in concrete is presented. It is based on the mass balance equation for calcium in the porous material. This model is implemented in a Finite Volume code and validated by comparison between numerical simulations and experimental results found in the literature, for cement pastes and mortars as well as for concretes, with a satisfactory agreement. Then, a parametric survey has been performed. It enlightens the large influence of porosity and diffusivity on the leaching kinetic. In complement, a large experimental campaign, which aims at acquiring data on the material characteristics variability (within several batches for a same concrete mix design) has been undertaken. This campaign investigates porosity and the degradation depth at different times considering accelerated leaching under variable temperature. Nevertheless, the coefficient of tortuosity (which partially controls diffusivity in concrete) cannot be directly measured, although it is an important parameter to model the calcium diffusion process. Therefore, an inverse identification tool is developed and validated, based upon the Artificial Neural Network theory, using the available experimental data as input data and the numerical model for the network training.

A line tension approach is reviewed to model slip transfer across tilt grain boundaries (GBs). It is implemented as a constitutive rule in the already existing two-dimensional discrete dislocation plasticity model of polycrystalline thin films. GBs are treated as obstacles to dislocation motion but with a finite strength. Dislocation transmission across a GB is potentially allowed, provided that three known geometrical criteria are satisfied. If allowed, the motion of the dislocation across the GB is enabled by dynamically creating a GB source near the GB, the stress on which must exceed the boundary strength. To separate transmission effects from other discrete dislocation features of the plastic deformation of thin films, comparisons are carried out by modelling GBs as impenetrable barriers to dislocation motion. It is shown that slip transfer tends to make the film softer if the density of bulk sources is sufficiently low. Since the position of the boundary source lies within the high-stress region of dislocation pile-ups, once activated the transmission process becomes independent of the source strength. In addition, the Bauschinger effect (BE) in thin films has been studied and a decrease of the BE is seen when dislocation transmission across GBs is enabled.

Ab initio calculations of the structural, electronic and thermodynamic properties of Hf2Ni, HfNi, HfNi2 and HfNi5 are presented. Using all-electron augmented plane waves plus local orbitals (APW+lo) method the relative stability of the selected compounds was determined by calculating their enthalpies of formation and cohesive energies. In addition, their electronic structure and bonding properties were determined. The results are discussed in view of the potential application of these intermetallics as materials for hydrogen storage.

The first stages of precipitation in Fe–Nb–C–N alloys exhibit mono-atomic coherent platelets, analogous to the Guinier–Preston zones. With an ab initio approach, we evaluated for various NbX (X = C, N) bulk phases their formation enthalpies and their stability under strains similar to those induced by the coherency of the platelets with the α-iron matrix. It appears that the nitrogen- and to a lesser extent the carbon-rich precipitates are likely to adopt a structure connected to the bulk CW hexagonal phase, according to an inedited ‘prismatic on cube’ orientation with the body centred cubic matrix.