Search results for "Computational Mechanic"
showing 10 items of 159 documents
Study of the influence of dithizone as an eco-friendly corrosion inhibitor on the corrosion behaviour of AA7075 aluminium alloy in neutral chloride s…
2021
The effect of 1,5-diphenylthiocarbazone (dithizone) as an eco-friendly corrosion inhibitor for protection of AA7075 aluminium alloy in chloride containing aggressive environment was studied by means of weight-loss, electrochemical measurements and Raman spectroscopy. The results indicate that the addition of dithizone decreases significantly the corrosion rate of AA7075 alloy, with efficiency proportional to the inhibitor concentration. The polarization curves show that dithizone works as mixed-type inhibitor to slow down the anodic and cathodic reaction kinetic. The morphology revealed by scanning electron microscopy and the Raman spectroscopy analysis clearly shows that the inhibitor cont…
A three-dimensional cohesive-frictional grain-boundary micromechanical model for intergranular degradation and failure in polycrystalline materials
2013
Abstract In this study, a novel three-dimensional micro-mechanical crystal-level model for the analysis of intergranular degradation and failure in polycrystalline materials is presented. The polycrystalline microstructures are generated as Voronoi tessellations, that are able to retain the main statistical features of polycrystalline aggregates. The formulation is based on a grain-boundary integral representation of the elastic problem for the aggregate crystals, that are modeled as three-dimensional anisotropic elastic domains with random orientation in the three-dimensional space. The boundary integral representation involves only intergranular variables, namely interface displacement di…
Turbulence structures over irregular rough surfaces
2010
Turbulent flow in a channel with irregular two-dimensional rough surfaces is analysed through wall-resolving large eddy simulation (LES). Both walls of the channel are roughened through the superimposition of sinusoidal functions having random amplitude and four different wavelengths. The downward shift of the velocity profile in the log region due to the roughness, known as roughness function, is well captured in the simulations. The spanwise and wall-normal turbulence intensities are found to increase with the roughness height, while the streamwise component decreases. The analysis of the Reynolds stress anisotropy tensor highlights a tendency towards isotropisation, confirmed by the vort…
An enhanced grain-boundary framework for computational homogenization and micro-cracking simulations of polycrystalline materials
2015
An enhanced three-dimensional (3D) framework for computational homogenization and intergranular cracking of polycrystalline materials is presented. The framework is aimed at reducing the computational cost of polycrystalline micro simulations, with an aim towards effective multiscale modelling. The scheme is based on a recently developed Voronoi cohesive-frictional grain-boundary formulation. A regularization scheme is used to avoid excessive mesh refinements often induced by the presence of small edges and surfaces in mathematically exact 3D Voronoi morphologies. For homogenization purposes, periodic boundary conditions are enforced on non-prismatic periodic micro representative volume ele…
Mechanical behaviour of natural cow leather in tension
2009
We study experimentally the microstructure and mechanical behavior of natural cow leather. Tensile tests are performed using leather strips to observe their deformation, creep and failure. It is found that the microstructure of cow leather is a layered, complicated network of fibers of different sizes from a few to a few hundreds of nanometers in diameter. They show nonlinear stress-strain relations and viscoelastic behavior. The effect of humidity is also examined. A simple theoretical model of a multilayered beam is proposed to describe the most basic behavior in tension.
Application of infrared thermography as a complementary technique to conventional imaging techniques in paediatrics: case studies
2018
The use of infrared thermography has been shown to be useful in several areas. Its applicability in medicine is based on the fact that the skin emits spontaneously and continuously infrared radiati...
Modelling intergranular and transgranular micro-cracking in polycrystalline materials
2018
Abstract In this work, a grain boundary formulation for intergranular and transgranular micro-cracking in three-dimensional polycrystalline aggregates is presented. The formulation is based on the displacement and stress boundary integral equations of solid mechanics and it has the advantage of expressing the polycrystalline problem in terms of grain boundary variables only. The individual grains within the polycrystalline morphology are modelled as generally anisotropic linear elastic domains with random spatial orientation. Transgranular micro-cracking is assumed to occur along specific cleavage planes, whose orientation in space within the grains depend upon the crystallographic lattice.…
A microstructural model for homogenisation and cracking of piezoelectric polycrystals
2019
Abstract An original three-dimensional generalised micro-electro-mechanical model for computational homogenisation and analysis of degradation and micro-cracking of piezoelectric polycrystalline materials is proposed in this study. The model is developed starting from a generalised electro-mechanical boundary integral representation of the micro-structural problem for the individual bulk grains and a generalised cohesive formulation is employed for studying intergranular micro-damage initiation and evolution into intergranular micro-cracks. To capture the electro-mechanical coupling at the evolving damaging intergranular interfaces, standard mechanical cohesive laws are enriched with suitab…
Transport properties of heterogeneous materials. Combining computerised X-ray micro-tomography and direct numerical simulations
2009
Feasibility of a method for finding flow permeability of porous materials, based on combining computerised X-ray micro-tomography and numerical simulations, is assessed. The permeability is found by solving fluid flow through the complex 3D pore structures obtained by tomography for actual material samples. We estimate overall accuracy of the method and compare numerical and experimental results. Factors contributing to uncertainty of the method include numerical error arising from the finite resolution of tomographic images and the rather small sample size available with the present tomographic techniques. The total uncertainty of computed values of permeability is, however, not essentiall…
LRPH device optimization for axial and shear stresses
2020
The paper concerns an in-depth study of a special connection for steel structures and the formulation of the related optimal design problem. The connection is called Limited Resistance Rigid Perfectly Plastic Hinge (LRPH) and it represents an innovative device devoted to join steel beam elements of frame structures. The device consists in a sequence of steel cross sections constituted by two parallel flanges with suitably different thickness connected by as many webs with constant and equal thickness. The fundamental innovation of the device is the possibility of designing special connections with elastic stiffness and limit strength independent of each other. Such a special characteristic …