1,721,000 research outputs found
Triple junctions in polycrystalline silicon: a numerical study based upon atomistic simulations
No full textAtomistic study of the interaction between a microcrack and a hard inclusion in beta-SiC
No full textMultiscale Modeling of Composite Materials by a Multifield Finite Element Approach
No full textWe present a multiscale model for composite materials based on the theory of multifield continua. Such a model includes additional fields besides the standard stress and deformation, allowing representing microstructures in a continuous medium. The multiscale model was implemented in a new finite element code, MUSCAFE. Numerical examples describing a fibre-reinforced composite material with a porous (microcracked) elastic matrix are presented. We firstly discuss an uncoupled model, in which the microstructural relaxation does not influence the macroscopic displacement field. Then, the first stage of development of a fully-coupled model is described. Here appropriate coupling tensors describe the interaction between displacement and microstructure at the macroscopic level, thereby reflecting the microscopic interaction laws between microstructural elements and the matrix. The latter laws are derived by a combination of theoretical assumptions and atomistic molecular dynamics simulation
Atomic scale origin of crack resistance in brittle fracture
No full textWe investigate the physical meaning of the intrinsic crack resistance in the Griffith theory of brittle
fracture by means of atomic-scale simulations. By taking cubic SiC as a typical brittle material, we show
that the widely accepted identification of intrinsic crack resistance with the free surface energy underestimates
the energy-release rate. The strain dependence of the Young modulus and surface energy, as well
as allowance for lattice trapping, improve the estimate of the crack resistance. In the smallest scale limit,
crack resistance can be fitted by an empirical elastoplastic model
Multiscale modelling of materials by a multifield approach: microscopic stress and strain distribution in fiber-matrix composites
No full textA recently developed multiscale, multifield model is used to study the elastic response of a fiber-reinforced polymer composite material under different loading conditions. The multifield model is based on the theory of microstructured continua, and allows the introduction of microstructural variables (in this case the local microfiber orientation) within a standard continuum model. The numerical solution is implemented in a finite element approach. By simulated loading tests on a model system, we show that the multifield model goes well beyond the conventional anisotropic Cauchy solution, and can effectively incorporate the dependence of the elastic response on (i) an internal length scale, representing the actual fiber length, and (ii) the local fiber orientation
Atomic scale modelling of the interaction between a crack tip and nanosized elastic inclusions in beta-SiC
No full text
Fracture in brittle materials: the atomic-scale viewpoint
No full textWe present the basic formalism, as well as the underlying physical picture of atomistic simulations, as applied to the investigation of materials mechanical behavior. In particular, we discuss brittle fracture in cubic silicon carbide, proving that atomistic simulations are not only consistent with elementary continuum fracture mechanics, but also do provide a better physical insight on atomic-scale features, e.g. lattice trapping. Finally, we show how atomistic simulations could be used as a provider of constitutive relations to be possibly used in continuum modeling
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