Numerical analysis of strain-induced surface phenomena in aluminum alloys

Mesoscale surface deformation in polycrystalline aluminum alloys subjected to uniaxial tension is numerically investigated. Three-dimensional polycrystalline models with equiaxial and extended grains peculiar to rolling are constructed by a step-by-step packing method. Calculation results have shown that the grain structure is responsible for the mesoscale surface roughening under uniaxial tension. The roughness pattern is affected by the microstructure and loading conditions. In a specimen with equiaxial grains and in a textured material loaded across the rolling direction surface relief is very pronounced in comparison with the extended grain structure loaded along rolling direction

A numerical simulation of the deformation and fracture of a material with a porous polysilazane coating

A numerical analysis of the deformation and fracture mechanisms involved in a material with a porous ceramic coating under tension and compression is presented. The dynamic boundary-value problem in the plane strain formulation is solved numerically by the finite difference method. To take an explicit account of the substrate-coating interface and porous coating microstructure in the calculations, a curvilinear mesh generation algorithm based on the solution according to elasticity theory has been developed. A two-dimensional curvilinear mesh generated in this work was used to simulate the uniaxial loading of a material with a porous coating. The fundamental difference between the fracture mechanisms operating in the coated material in the cases of tension and compression was found to be related with the formation of local regions experiencing bulk tension in both cases

A computational analysis of the interfacial curvature effect on the strength of a material with a modified surface layer

The mechanisms of the deformation and fracture of coated materials with varying coating thickness and coating-substrate interfacial curvature parameters are investigated. The boundary-value problem in the plane strain formulation is solved numerically, using the finite-difference method. In the calculations, an explicit account is taken of experimental and model microstructures with irregular and sinusoidal coating-substrate interface geometries, respectively. The stress concentration in the near-interface region is shown to increase with decrease in the coating thickness and increase in the sinusoidal interface amplitude. This dependence is nonlinear in character

Numerical study of the surface-hardening effect on surface phenomena in 3D polycrystalline specimens

Surface hardening effect on the mesoscale surface deformation in polycrystalline specimens subjected to uniaxial tension is numerically studied. Basing on the experimental findings, three-dimensional microstructure-based constitutive models of the unhardened and surface-hardened polycrystalline specimens are constructed. The mechanical behavior of the polycrystalline models is analysed numerically by the finite-difference method. The grain structure is shown to be responsible for the free surface roughening under uniaxial loading. Microscale stresses acting in the bulk of the material across the free surface give rise to the formation of surface ridges and valleys. The hardened layer in a surface-hardened specimen moves the grain structure away from the free surface, thus smoothing out the microscale folds caused by displacements of individual grains. The thicker is the modified layer, the smoother is the surface relief

Numerical analysis of strain-induced surface phenomena in aluminum alloys

Mesoscale surface deformation in polycrystalline aluminum alloys subjected to uniaxial tension is numerically investigated. Three-dimensional polycrystalline models with equiaxial and extended grains peculiar to rolling are constructed by a step-by-step packing method. Calculation results have shown that the grain structure is responsible for the mesoscale surface roughening under uniaxial tension. The roughness pattern is affected by the microstructure and loading conditions. In a specimen with equiaxial grains and in a textured material loaded across the rolling direction surface relief is very pronounced in comparison with the extended grain structure loaded along rolling direction

Numerical study of the surface-hardening effect on surface phenomena in 3D polycrystalline specimens

Surface hardening effect on the mesoscale surface deformation in polycrystalline specimens subjected to uniaxial tension is numerically studied. Basing on the experimental findings, three-dimensional microstructure-based constitutive models of the unhardened and surface-hardened polycrystalline specimens are constructed. The mechanical behavior of the polycrystalline models is analysed numerically by the finite-difference method. The grain structure is shown to be responsible for the free surface roughening under uniaxial loading. Microscale stresses acting in the bulk of the material across the free surface give rise to the formation of surface ridges and valleys. The hardened layer in a surface-hardened specimen moves the grain structure away from the free surface, thus smoothing out the microscale folds caused by displacements of individual grains. The thicker is the modified layer, the smoother is the surface relief

A numerical analysis of formation of the surface relief: A single inclusion model

The influence of the material inhomogeneity on free surface roughening under uniaxial loading is simulated numerically in the framework of the mechanics of heterogeneous media, using a model of a single cubic inclusion embedded in a matrix as an example. Mechanical problems in 2D and 3D formulations are solved numerically by the finite-difference and finite-element methods. The stress-strain state responsible for the free surface roughening is examined. The effects of the inclusion orientation and location relative to the free surface and inclusion-to-matrix elastic modulus ratio on the surface relief characteristics are discussed

Mesomechanical numerical modeling of the stress-strain localization and fracture in an aluminum alloy with a composite coating

A numerical analysis of plastic strain localization and fracture in an aluminum alloy with a composite aluminum (Al) – titanium carbide (TiC) coating providing oxidation protection is presented. Boundary-value problems in plane strain and three-dimensional formulations are solved numerically by the finite-difference and finite-element methods, respectively. The AlTiC interface geometry corresponds to the configuration found experimentally and is accounted for explicitly in calculations. An algorithm to build a 3D finite-element model of TiC particles is developed. To simulate the mechanical response of the aluminum substrate and composite coating, use was made of an elastic-plastic model with isotropic strain hardening and a fracture model taking into account crack initiation and growth in the regions experiencing tensile stresses. Local regions of bulk tension are shown to arise near the interfaces even under simple uniaxial compression of the coated material, which controls the mechanisms of plastic strain and fracture localization at the mesoscale level. The role of technological residual stresses is revealed