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This paper demonstrates a method for calculating the tension of a system with a curved interface from a molecular dynamics simulation. To do so, the pressure of a subset of the system is determined by applying a local (virtual) mechanical deformation, fitting the response to that of a bulk fluid, and then using the Young-Laplace equation to infer the tension of the interface. The accuracy of the method is tested by calculating the local pressure of a series of water simulations at various external pressures. The tension of a simulated curved octane-water interface is computed with the method and compares well with the planar tension (≈ 46.7 dyn/cm). Finally, an ambiguity is resolved between the Harasima and Irving-Kirkwood methods of calculating the local pressure as a means for computing the tension. [ABSTRACT FROM AUTHOR]

A VOF-based approach for the detailed computation of reactive mass transfer at rising gas bubbles is presented. Based on a local approximation of the transport equation at the fluid interface, a reactive subgrid-scale model for uncoupled reactions within the concentration boundary layer is derived. For this purpose, the convective term of the boundary layer description is modeled, reducing the governing nonlinear partial differential equation to a one-dimensional nonlinear differential equation. A numerical scheme is developed to solve the remaining differential equation and obtain the concentration gradient at the fluid interface. Mesh convergence for the resulting scheme is shown. The method is validated within the VOF code FS3D by comparing to local and integral Sherwood numbers, and Schmidt numbers up to 1000 for a 3D reactive Stokes flow regime around a rising spherical bubble (Hadamard–Rybczynski flow field). Local Sherwood numbers show significant reactive mass transfer into the liquid phase in the wake region of the rising bubble. [ABSTRACT FROM AUTHOR]

Hot stamping tools with cooling systems are key facilities for hot stamping processes in the automotive industry. In hot stamping, the tools are heated by workpieces and rapidly cooled by cooling water. The thermal deformation of the tools has a significant influence on the properties of the hot stamped parts and the useful life of the tools. In this paper, a multi-field simulation method is proposed for analysis of deformation in the tools. Based on a mesh based parallel code coupling interface, a thermal-fluid-mechanical coupled model is established to analyse the cooling effect and the deformation of the tools. The experimental set-up was built to verify the multi-field coupling model. It is shown that the cooling rate of the hot stamped part was 217°C s−1, higher than the critical cooling rate of 30°C s−1. The temperature history of the hot formed part was in good agreement with the experimental result. The cooling ducts were deformed because of the thermal expansion of the hot tools. This led to stress concentration at the rectangular corner of the ducts. The speed of cooling water flow increased by 112% through the bottom ducts, while at the corners of the ducts, the speed was very low and a 'hot spot' appeared. [ABSTRACT FROM AUTHOR]

Highlights: [•] This paper presents a micromechanics-based approach to the interface modeling in metal forming. [•] It catches the nature of friction and heat transfer and implements together both models. [•] We give insight into how a process designer could evaluate a candidate tooling design. [•] Chilling due to better heat transfer leads to increased resistance to deformation. [•] The model gives qualitatively and quantitatively promising results for many combinations. [ABSTRACT FROM AUTHOR]

This paper presents a study on the numerical performance of three contact simulation methods, namely, the interface element, thin-layer element, and contact analysis methods, through the analysis of the contact behavior between the concrete face slab and the dam body of a high concrete-faced rockfill dam named Tianshengqiao-I in China. To investigate the accuracy and limitations of each method, the simulation results are compared in terms of the dam deformation, contact stress along the interface, stresses in the concrete face slab, and separation of the concrete face slab fromthe cushion layer.\ In particular, the predicted dam deformation and slab separation are compared with the in-situ observation data to classify these methods according to their agreement with the in-situ observations. It is revealed that the interface element and thin-layer element methods have their limitations in predicting contact stress, slab separation, and stresses in the concrete face slab if a large slip occurs. The contact analysis method seems to be the best choice whether the separation is finite or not. [ABSTRACT FROM AUTHOR]

Abstract: A finite element model has been developed for analyzing of the dynamic response of sandwich plates with partially damaged facesheet-to-core interface. The effect of intermittent dynamic contact between the fragments detached at the damaged interface is taken into account for simulation of sandwich plates'' vibrations. Transient and forced dynamic responses of the sandwich plates damaged by debonding have been obtained by using the ABAQUS/Explicit code. The influence of the local strongly nonlinear contact behavior on the global dynamics of the sandwich plates is examined. [Copyright &y& Elsevier]

Abstract: In recent years FRP (Fiber Reinforced Polymer) technology has been developed to repair damaged concrete structures. This work proposes to investigate the complex mechanism of stress–strain evolution at the FRP interface until complete debonding as well as when long-term loads are accounted for. The study has been performed by means of a fully three-dimensional approach within the context of damage mechanics, to appropriately catch transverse effects and normal stresses, developing a realistic and comprehensive study of the delamination process. The adhesion properties have been reconstructed through a contact model incorporating an elastic-damaged constitutive law, relating inter-laminar stresses acting in the sliding direction. A F.E. research code (FRPCON3D) has been developed, including a numerical procedure accounting for Mazars’ damage law inside the contact algorithm. The code is also able to describe the delamination process when considering the effects from different concrete surface preparations. Additionally, it has been upgraded to describe the long-term behaviour of composite structures by means of two visco-elastic formulations: (i) Bažant’s B3 law has been considered for the concrete component, where creep effect is composed by three different terms, i.e. the elastic part, basic creep and drying creep; (ii) for FRP’s fibres and matrix a micromechanical approach has been implemented. The numerical results have been calibrated and validated against available experimental evidences. [Copyright &y& Elsevier]

Abstract: In this work, an axisymmetric plasticity model is used to simulate the concrete-steel interface behavior. A nonlocal correction is here introduced in order to capture the degradation of the bond due to splitting cracks. Damage of the interface is also modeled as a function of the rib spacing, allowing application of the model to different bar diameters. The model is able to capture the transition from splitting to pull-out failure and to yielding of bars with the same set of predefined interface parameters, showing the predictive character of the model. The development of macroscopic cracks is also correctly simulated. [Copyright &y& Elsevier]

Abstract: The influence of the ambient temperature on the stress, deformation and temperature of a dump truck tire has been predicted with the virtual tire model established in this work by employing the finite element method (FEM) and Algor software. The nonlinear stress–strain relationship of tire rubber material has been given by Mooney–Rivlin material model. The hysteresis and loss strain energy density have been related to give the heat generation rate. A two-dimensional (2D) FE model of rolling radial tire has been built in Algor environment according to the actual construction of bridgestone 24.00R35 tire adopted for Caterpillar Earth Mover 775E Model. The model consists of the tread, belt, carcass, air filled volume and tire–rim interface. The material properties of the components and boundary conditions from tire–rim contact and tire–road contact are considered. The mechanical event simulation (MES) with nonlinear material model and the steady-state heat transfer analysis have been performed. The analysis results of the tire stress, deformation and temperature are presented under the ambient temperatures ranging from −40 to 40°C conditions at the Syncrude mine in Canada. The results show that the effect of the ambient temperature on the tire deformation is larger than on the tire stress. The increase of ambient temperature will cause the tire temperature rise. This study provides a comprehensive modeling and analysis that provide key to avoid tire temperature related failure. [Copyright &y& Elsevier]

This paper proposes a substructural damage identification approach without the information of responses and forces at the interface degrees-of-freedom. It is based on the response reconstruction technique using the unit impulse response function in the wavelet domain. The finite element model of the target substructure and acceleration measurement data from the damaged substructure are required in the identification. A dynamic response sensitivity-based method is used for the substructural finite element model updating, and local damage is identified as a change in the elemental stiffness factors. The adaptive Tikhonov regularization technique is adopted to improve the identification results with the measurement noise effect. Numerical studies on a three-dimensional boxsection girder are conducted to validate the proposed method of substructural damage identification. The simulated damage can be identified effectively even with 10% noise in the measurements and a 5% coefficient of variation in the elastic modulus of material of the structure. [ABSTRACT FROM AUTHOR]

Abstract: Considering the mismatch of coefficient of thermal expansion (CTE) of Cu and W phase and temperature gradient, internal and external thermal load are applied on meso-scale 2D representative volume element (RVE) of CuW alloys under thermal shock, respectively. Void volume fraction (VVF) and VVF induced crack are determined by finite element method (FEM) utilizing Gurson–Tvergaard–Needleman (GTN) model, and the driving forces for damage nucleation and growth are analyzed with normal and shear stress as well. The simulation results show that damage and damage induced crack initiate from the vertex of W grain and grow along W/Cu interface, then propagate into Cu phase. After thermal shock experiment on CuW specimen by high voltage arc, micro cracks present along W/Cu interfaces and inside Cu phase, which is in good agreement with simulation results. [Copyright &y& Elsevier]

Abstract: A finite element (FE) model has been developed for the analysis of the dynamic response of sandwich plates with impact-induced damage involving core crushing, face sheet damage and core-to-face sheet debonding. The effect of intermittent contact in fragments detached at the damaged interface due to the impact event is examined. Simulation of the strongly nonlinear transient and steady-state dynamic responses of impact-damaged sandwich plates are carried out with the FE code ABAQUS. The potential of the obtained numerical results for detecting and locating impact-induced damage is discussed. [Copyright &y& Elsevier]

The objective of presented work is to simulate the response of 2D hydrogel when subjected to the varying pH of buffer solution and initial fixed-charge concentration inside the hydrogel. The novelty of the work is that this is the first attempt to perform the 2D simulation of pH-responsive hydrogel by novel strong-form meshless method, such as random differential quadrature (RDQ) method. The analytical equations, derived for the hydrogel deformation in the x and y directions, are numerically verified by the square shaped hydrogel disc. The jumps in the distributions of ionic concentrations and electrical potential, across the interface between solution and hydrogel, are effectively captured by the RDQ method. A novel approach is proposed to correctly impose natural boundary conditions for non-uniform boundary. The effects of solution pH and initial fixed-charge concentration on the hydrogel swelling are also successfully investigated. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, an enriched finite element method is presented for numerical simulation of saturated porous media. The arbitrary discontinuities, such as material interfaces, are encountered via the extended finite element method (X-FEM) by enhancing the standard FEM displacements. The X-FEM technique is applied to the governing equations of porous media for the spatial discretization, followed by a generalized Newmark scheme used for the time domain discretization. In X-FEM, the material interfaces are represented independently of element boundaries and the process is accomplished by partitioning the domain with some triangular sub-elements whose Gauss points are used for integration of the domain of elements. Finally, several numerical examples are analyzed, including the dynamic analysis of the failure of lower San Fernando dam, to demonstrate the efficiency of the X-FEM technique in saturated porous soils. [Copyright &y& Elsevier]

The shapes of the interfacial delamination crack and stress states during wedge indentation in a soft-film-on-hard-substrate system were investigated systematically using the three-dimensional (3D) nite element simulation and wedge indentation experiment. In the simulation, a traction--separation law was used to characterize the failure behaviors of the interface. The effects of the wedge indenter tip length and the lm thickness on the onset and growth of interfacial delamination were analyzed. It was shown that a two-dimensional (2D) to 3D transition of stress states occurred depending on the ratio of indenter length to lm thickness. Furthermore, the interfacial delamination process by wedge indentation was conducted experimentally, and comparisons between the computational and experimental results yielded quantitative good agreement. Finally, a straightforward criterion based on the curvature of the delamination crack front was proposed to indicate the transition of stress states during the interfacial delamination. A guideline was therefore proposed to classify the 2D and 3D stress states for extracting the interface adhesion properties. [ABSTRACT FROM AUTHOR]

Abstract: The interfaces between different materials can be coherent (heteroepitaxial), semi-coherent or incoherent. A semi-coherent interface is one in which the misfit between the two phases is partially or fully accommodated by discrete interfacial dislocations. A precipitate–matrix interface may undergo a transition from coherent to semi-coherent through dislocation nucleation or interactions with pre-existing dislocations during plastic deformation. Dislocation–precipitate interactions can also be modified significantly by the degree of coherency of the interface. In this study, we examine how plasticity mediates the change from coherent to semi-coherent interfaces in the case of a misfitting spherical particle, i.e. how the matrix dislocations relax the misfit of the particle and form dislocation structures on the particle–matrix interface. Various stable dislocation structures on the semi-coherent particles are studied. We also examine how dislocation–particle interactions are influenced by the change in the particle from coherent to semi-coherent. These simulations are performed using a three-dimensional level set dislocation dynamics method. [Copyright &y& Elsevier]

Abstract: The folding of thin shells around localized lines occurs in several situations of engineering interest, such as in buckling induced deformation, as the consequence of crash, in industrial processes like metal forming, in the deployment of folded membranes, in packaging related processes. In this paper an interface element, allowing for displacement and rotation discontinuities, to be placed between two adjacent 4-node Mindlin–Reissner shell finite elements, is developed for a computationally effective simulation of this type of localized deformation. The large displacement and rotation kinematics of the interface element is discussed, arriving at a rigid-rotation free element tangent stiffness matrix. An adaptive dynamic relaxation scheme is proposed for the evolutionary analysis of the quasi-static structural response. To test the element formulation, a simple coupled membrane-bending elastoplastic behavior is assumed. The element is used for the simulation of few examples taken from the literature, where the structural response is characterized by the formation of plastic hinges, exhibiting good accuracy and computational effectiveness. [Copyright &y& Elsevier]

Abstract: Various interfaces in Zn coated steel are examined for their stability on the basis of two conflicting requirements of minimum deformation at a maximum absorption of shear energy. The shearing process is simulated using a Molecular Dynamics technique and meta-models of both energy and strain are constructed using an Evolutionary Neural Network that itself evolved through a multi-objective Genetic Algorithm. Simultaneous optimization of deformation and energy absorption is conducted with a Predator–prey Genetic Algorithm and the resulting Pareto frontiers are analyzed and discussed. The findings show good correspondence with existing experimental observations. [Copyright &y& Elsevier]

This paper presents a finite-element simulation of the interfacial flow during propulsion of water walkers such as fishing spiders and water striders. The unsteady stroke of the driving leg is represented by a two-dimensional cylinder moving on a specified trajectory. The interface and the moving contact lines are handled by a diffuse-interface model. We explore the mechanism of thrust generation in terms of the interfacial morphology and flow structures. Results show that the most important component of the thrust is the curvature force related to the deformation of the menisci and the asymmetry of the dimple. For water walkers with thick legs, the pressure force due to the inertia of the water being displaced by the leg is also important. The viscous force is negligible. An extensive parametric study is performed on the effect of leg velocity, stroke depth, leg diameter and surface wettability. The propulsive force is insensitive to the contact angle on the leg. However, the hydrophobicity of the leg helps it detach from the surface during the recovery stroke and thus decreases the resistance. It is also important for averting or delaying penetration of the interface at large rowing velocity and depth. In two dimensions, surface waves are more efficient than vortices in transferring the momentum imparted by the leg to the water. [ABSTRACT FROM AUTHOR]

The dynamical response of an isothermal liquid bridge to a coaxial gas stream is examined from axisymmetric numerical simulations of the Navier-Stokes equations. The simulation method is previously validated by calculating the temporal evolution of the first oscillation mode in both cylindrical and axisymmetric liquid bridges. The comparison with other theoretical approaches and experiments shows good agreement in most cases, although significant discrepancies are found between the simulation and the experimental values of the damping rate for hexadecane. The simulation of a liquid bridge in a coaxial gas stream shows that a recirculation cell always appears in the liquid driven by the gas viscous stress on the free surface. The recirculation cell speed depends quasilinearly on the gas velocity for the range of gas flow rates considered. If the gas stream and gravity have the same direction, then the speed of the recirculation cell increases considerably due to the free surface deformation of the liquid bridge at equilibrium. This effect does not occur when gravity has the opposite direction because viscous dissipation in the liquid increases in this case. If the gas stream and gravity point downward, the liquid bridge shrinks at the upper part and bulges at the lower owing to the accumulation of momentum there. The same occurs for zero gravity, but noncylindrical liquid bridges deform more than cylindrical shapes with the same slenderness. If one inverts the direction of the gravity force, the interface deformation caused by the gas stream is the opposite, and its magnitude is smaller. The magnitude of the free surface deformation depends almost linearly on the gas stream velocity for both zero and normal gravity conditions. [ABSTRACT FROM AUTHOR]

Abstract: The intermolecular potential model of the lattice Boltzmann method (LBM) is used to simulate the effect of an imposed electric field on droplet formation process from mixing of immiscible fluid streams in a 2D microchannel with non-wetting walls. The electrodes are placed near the inlet of the main channel where droplet breakup occurs. Simulation results show that droplet size decreases and formation frequency increases as the intensity of the electric field is increased. This is because the gap between the emerging droplet and main channel wall is decreased under the action of the electric field during the droplet formation process, which induces the emerging droplet to block the continuous phase more effectively. The obstruction increases the pressure difference across the droplet interface, leading to stronger squeezing effects on the neck of the droplet. For a fixed velocity ratio of the continuous phase to the disperse phase, there exists a critical value of electric field intensity for which the droplet begins to touch the surfaces of the electrodes. At this critical value of electric field intensity, the droplet size suddenly decreases and droplet formation frequency suddenly increases drastically. At high electric field intensity when the electric force dominates the flow field, deformation of droplet is relatively independent of the velocity of the continuous phase. Simulation results show that an electric field can be used to control droplet size and droplet formation frequency effectively. [ABSTRACT FROM AUTHOR]

Abstract: We analyze the processes of thermal softening, melting and subsequent melt lubrication that occur during the high speed sliding of a metal piece on another metal block. The temperature rise in the slider arising from both high speed interface friction and from the energy dissipated during plastic deformations is computed using simple analysis and the finite element method. Subsequently, we propose a mathematical model for the transient lubrication problem that describes the behavior of the molten film at the slider–rail interface. This model successfully predicts the evolution process of the melt thickness and the melt front velocity of the liquid film; these predictions agree with the experimentally observed dynamics of molten film better than those from other existing models. [ABSTRACT FROM AUTHOR]

Abstract: The ply delamination which is known as a principle mode of failure of layered composites due to separation along the interfaces of the layers is one of the main concerns in designing of composite material structures. In this regard, the effect of hybrid laminate lay-up with different delamination positions in composite beam was investigated. The Charpy impact test was chosen to study the energy absorbing capability of delaminated composite beam. Hybrid composite beams were fabricated from combination of glass/epoxy and carbon/epoxy composites. It was shown that composite beams with closer position of delamination to impacted surface are able to absorb more energy in comparison with other delamination positions in hybrid and non-hybrid ones. The Charpy impact test of delaminated composite beams was also simulated by finite element software LS-DYNA and the results were verified with the relevant experimental results. [Copyright &y& Elsevier]

Abstract: This paper reports numerical simulations of selective withdrawal of Newtonian and polymeric liquids, and complements the experimental study reported in the accompanying paper (Zhou and Feng ). We use finite elements to solve the Navier–Stokes and constitutive equations in the liquid on an adaptively refined unstructured grid, with an arbitrary Lagrangian–Eulerian scheme to track its free surface. The rheology of the viscoelastic liquids are modeled by the Oldroyd-B and Giesekus equations, and the physical and geometric parameters are matched with those in the experiments. The computed interfacial deformation is in general agreement with the experimental observations. In particular, the critical condition for interfacial rupture is predicted to quantitative accuracy. Furthermore, we combine the numerical and experimental data to explore the potential of selective withdrawal as an extensional rheometer. For Newtonian fluids, the measured steady elongational viscosity is within 47% of the actual value, apparently with better accuracy than other methods applicable to low-viscosity liquids. For polymer solutions, an estimated maximum error of 300% compares favorably with prior measurements. [Copyright &y& Elsevier]

Abstract: The purpose of this paper is to understand the creep damage properties of thin film/substrate systems by bending creep tests. To this aim, a numerical study has been performed on the creep damage development of the thin film/substrate systems by implementing the Kachanov–Rabothov damage law into finite element models. The work may shed some light on the influence of the modulus ratio of the substrate to the thin film, the thickness of the thin film and the bending load. Finite element method (FEM) results show that three obviously damaged zones are found. The first is at the edge of the loading pin, the second is at the interface between the film and the substrate ahead of the loading pin edge, the last is at the edge of the supporting pin A. The influence of the modulus ratio of the substrate to the thin film on the bending creep damage is not obvious at the preliminary stage of creep time. However, with the lapse of time, the damage rate decreases with the increase of modulus ratio of the substrate to the thin film. The change of the thickness of the thin film and the bending load also influence the creep damage behavior of the thin film/substrate systems. [Copyright &y& Elsevier]

Abstract: The three-dimensional constitutive relations are constructed, respectively, for the fuel particles, the metal matrix and the cladding of dispersion nuclear fuel elements, allowing for the effects of large deformation and thermal-elastoplasticity. According to the constitutive relations, the method of modeling their irradiation behaviors in ABAQUS is developed and validated. Numerical simulations of the interfacial performances between the fuel meat and the cladding are implemented with the developed finite element models for different micro-structures of the fuel meat. The research results indicate that: (1) the interfacial tensile stresses and shear stresses for some cases will increase with burnup, but the relative stresses will decrease with burnup for some micro-structures; (2) at the lower burnups, the interfacial stresses increase with the particle sizes and the particle volume fractions; however, it is not the case at the higher burnups; (3) the particle distribution characteristics distinctly affect the interfacial stresses, and the face-centered cubic case has the best interfacial performance of the three considered cases. [Copyright &y& Elsevier]

Abstract: Thin tensile specimens of pseudoelastic NiTi shape memory alloys deform by the formation and propagation of distinct martensitic bands. During cyclic loading, functional fatigue (i.e., degradation of functional properties due to the repeated martensitic transformation) is limited to the regions that participate in the transformation. In this study, we present finite element calculations based on a simple elasto-plastic approach that utilizes strain softening to simulate localized transformation/deformation. We investigate the effect of typical experimental factors (clamping conditions and small superimposed bending moments during tensile testing) on the macroscopic mechanical behavior and on the propagation mode of the macroscopic phase interfaces. Moreover, we study how localized functional fatigue influences the macroscopic stress–strain data. The simulations demonstrate that a detailed understanding of experimental conditions and of cyclic experiments can be obtained by finite element modeling of localized deformation. [Copyright &y& Elsevier]

Abstract: A fuselage representative carbon fibre-reinforced multi-stiffener panel is analysed under compressive loading. An intact and pre-damaged configuration is loaded into the postbuckling region and further on until collapse occurs. An analysis tool is applied that includes an approach for predicting interlaminar damage initiation and degradation models for capturing interlaminar damage growth as well as in-plane damage mechanisms. Analysis of the intact panel configuration predicts collapse due to fibre fracture in the stiffeners close to the panel clamps, which agrees well with the results from experimental testing. The pre-damaged configuration was proposed containing Teflon-coated layers to generate the initial debonds in the skin-stiffener interface. The outcome of the simulation of this configuration shows that crack growth is not predicted to occur, which agrees with the observations of the experiment. A parametric study is conducted to investigate the effect of the skin-stiffener debond parameters such as length, width and location on crack growth and the collapse behaviour of the panel. It is found that the sensitivity of the panel design to the damage parameters is highly dependent on the postbuckling mode shape or displacement pattern, and particularly the extent to which this influences the conditions at the crack front. More broadly, the analysis tool is shown to be capable of capturing the critical damage mechanisms leading to structural collapse of stiffened composite structures in the postbuckling region. [Copyright &y& Elsevier]

Abstract: This paper reports on atomistic simulations of the interactions between the dominant lattice dislocations in γ-TiAl (ordinary screw and 〈101] superdislocations) with all three kinds of γ/γ-lamellar boundaries in polysynthetically twinned (PST) TiAl. The purpose of this study is to clarify the early stage of lamellar boundary controlled plastic deformation in PST TiAl. The interatomic interactions in our simulations are described by a bond order potential for L10-TiAl which provides a proper quantum mechanical description of the bonding. We are interested in the dislocation core geometries that the lattice produces in proximity to lamellar boundaries and the way in which these cores are affected by the elastic and atomistic effects of dislocation-lamellar boundary interaction. We study the way in which the interfaces affect the activation of ordinary dislocation and superdislocation slip inside the γ-lamellae and transfer of plastic deformation across lamellar boundaries. We find three new phenomena in the atomic-scale plasticity of PST TiAl, particularly due to elastic and atomic mismatch associated with the 60° and 120° γ/γ-interfaces: (i) two new roles of the γ/γ-interfaces, i.e. decomposition of superdislocations within 120° and 60° interfaces and subsequent detachment of a single ordinary dislocation and (ii) blocking of ordinary dislocations by 60° and 120° interfaces resulting in the emission of a twinning dislocation. [Copyright &y& Elsevier]

Abstract: Misfit dislocation is an important component of the semi-coherent interface. It is a line defect on interface, and strongly affects the structural and dynamical properties. In this work, we use an atomistic simulation method to study two representative dynamics of Pd/MgO interface: the fracture and slipping. The calculation shows that for both the two cases, misfit dislocation plays a critical role. However, the dislocation in the latter is much more important than in former, that it reduces the tensile stress (in fracture) for 26% but slip stress (in slipping) for three orders of magnitude. Also, some valuable parameters of misfit dislocation can be extracted from the atomistic simulation results by a simple derivation, such as the dislocation width, mass and velocity, which are determined as 14Å, 0.46awu/Å and 40m/s in this work. [Copyright &y& Elsevier]

Abstract: In glass–ceramics, the density difference between the new, semi-crystalline system, and the ambient phase requires a deformation of the grains. However, the first stage of surface induced crystallization is the creation of rigid shell, opposing the shrinkage. Therefore, an important stress appears inside the grain. If the average density of the new system is higher than that of the ambient phase, a tensile stress is generated. In the opposite case, a compressive stress is developed. As soon as the system is neither pure elastic body nor pure plastic one, the concentration of the stress energy depends on the distance from the interface. We describe theoretically the distribution profile of the stress energy. Depending on the stress attenuation parameter and the grain size, there are two solutions. The first one predicts a maximum in the middle of the grain. According to the second, there are two maxima close to the crystal/glass interface. This explains the appearance of cabbage like crystals or of crystalline grains with a pore in the center. [Copyright &y& Elsevier]