Asymptotic homogenization of metamaterials elastic plates

The asymptotic homogenization technique is applied to evaluate the effective properties of thin plates with periodic heterogeneity. The effect of shear deformation in the homogenization process is evidenced and the role of cell slenderness, besides that of the plate, is clarified by several numerical analyses.

Investigation of the effect of raster angle, build orientation, and infill density on the elastic response of 3D printed parts using finite element microstructural modeling and homogenization techniques

Although the literature is abundant with the experimental methods to characterize mechanical behavior of parts made by fused filament fabrication 3D printing, less attention has been paid in using computational models to predict the mechanical properties of these parts. In the present paper, a numerical homogenization technique is developed to predict the effect of printing process parameters on the elastic response of 3D printed parts with cellular lattice structures. The development of finite element computational models of printed parts is based on a multi scale approach. Initially, at the micro scale level, the analysis of micro-mechanical models of a representative volume element is used to calculate the effective orthotropic properties. The finite element models include different infill densities and building/raster orientation maintaining the bonded region between the adjacent fibers and layers. The elastic constants obtained by this method are then used as an input for the creation of macro scale finite element models enabling the simulation of the mechanical response of printed samples subjected to the bending, shear, and tensile loads. Finally, the results obtained by the homogenization technique are validated against more realistic finite element explicit microstructural models and experimental measurements. The results show that, providing an accurate characterization of the properties to be fed into the macro scale model, the use of the homogenization technique is a reliable tool to predict the elastic response of 3D printed parts. The outlined approach provides faster iterative design of 3D printed parts, contributing to reducing the number of experimental replicates and fabrication costs.

A 3D extension of pantographic geometries to obtain metamaterial with semi-auxetic properties

In this work we present a three-dimensional extension of pantographic structures and describe its properties after homogenization of the unit cell. Here we rely on a description involving only the first gradient of displacement, as the semi-auxetic property is effectively described by first-order stiffness terms. For a homogenization technique, discrete asymptotic expansion is used. The material shows two positive ([Formula: see text]) and one negative Poisson’s ratios ([Formula: see text]). If, on the other hand, we assume inextensible Bernoulli beams and perfect pivots, we find a vanishing stiffness matrix, suggesting a purely higher gradient material.

Development of Mupirocin- Tinidazole solid- Lipid Nanoparticles Loaded Topical gel for the Management of Bacterial Wound Infections

Solid lipid nanoparticles (SLNs) are novel drug carrier system which consists of a solid matrix composed of a lipid being solid at both room and body temperatures with a mean Particle Size (PS) between 50 and 1000 nm Mupirocin -Tinidazole solid-lipid nanoparticles were prepared using hot homogenization technique using Glyceryl monosterate, Stearic acid, Tween 80 and Poloxamer 188 using hot homogenization technique. Size of the nanoparticles was in the range of 83 to 211 nm with the zeta potential values between -2.1 to -5.2. Atomic Force Microscopy (AFM) confirms the spherical shape of solid lipid nanoparticles. Entrapment efficiency was best in the F1 formulation. In vitro release of the pure drug was found to be 75% of mupirocin and 66.5% of tinidazole at the end of 1 hr. Drug release from SLNs dispersion followed Korsermeyrs peppas-model, indicating fickian diffusion drug release, while that from the gel followed non Fickian model drug release. Antibacterial activity of the SLNs was less but the SLNs based gel shows no significant difference in activity to that of standard drug gentamycin against aerobic bacteria. The SLNs dispersion exhibited physicochemical stability under refrigeration upto 45 days without significant difference in particle size. Best formulation was developed into a topical gel using sodium alginate and it was evaluated for pH, viscosity, spreadbility, extrudability, bloom strength, Minimum Inhibitory Concentration (MIC) and Methicillin resistant staphylococcus aureus (MRSA). Extrudability and spreadability parameters of the gel are similar to that of marketed Mupirocin 2% cream formulation

Simple Homogenization-Based Approach to Predict Raveling in Porous Asphalt

In the Netherlands, more than 80% of the highways are surfaced by porous asphalt (PA) mixes. The benefits of using PA mixes include, among others, the reduction of noise and the improvement of skid resistance. However, pavements with PA mixes are known to have a shorter lifetime and higher maintenance costs as compared with traditional dense asphalt mixes. Raveling is one of the most prominent distresses that occur on PA mix pavements. To analyze the raveling distress of a PA mix pavement, the stress and strain fields at the component level are required. Computational models based on finite element methods (FEM), discrete element methods (DEM), or both, can be used to compute local stress and strain fields. However, they require the development of large FEM meshes and large-scale computational facilities. As an alternative, the homogenization technique provides a way to calculate the stress and strain fields at the component level without the need for much computation power. This study aims to propose a new approach to analyze the raveling distress of a PA mix pavement by using the homogenization technique. To demonstrate the application of the proposed approach, a real field-like example was presented. In the real field-like example, the Mori–Tanaka model was used as a homogenization technique. The commonly available pavement analysis tool 3D-MOVE was used to compute the response of the analyzed pavement. In general, it was concluded that the homogenization technique could be a reliable and effective way to analyze the raveling distress of a PA mix pavement.

Multi-Scale Probabilistic Analysis for the Mechanical Properties of Plain Weave Carbon/Epoxy Composites Using the Homogenization Technique

Probabilistic analyses of carbon fabric composites were conducted using the Monte Carlo simulation based on a homogenization technique to evaluate the mechanical properties of composites and their stochastic nature. First, the homogenization analysis was performed for a micro-level structure, which fiber and matrix are combined. The effective properties obtained from this analysis were compared with the results from the rule of mixture theory to verify the homogenization analysis. And, tensile tests were conducted to clearly evaluate the result and the reliability was verified by comparing the results of the tensile tests and homogenization analysis. In addition, the Monte Carlo simulation was performed based on homogenization analyses to consider the uncertainties of the micro-level structure combined of fiber and matrix. Next, the results of this simulation were applied to the macro-level structure combined of the tow and matrix to perform the Monte Carlo simulation based on the homogenization technique. Finally, the sensitivity analysis was conducted to identify the effect of constituents of the carbon plain weave composite and the linear correlation of the micro- and macro-level structures combined of the fiber/matrix and tow/matrix, respectively. The findings of this study verified that the effective properties of the plain weave carbon/epoxy composite and their uncertainties depended on the properties of the carbon fiber and epoxy, which are the basic constituents of plain weave carbon/epoxy composites.