Studying the Tensile Behaviour of GLARE Laminates: A Finite Element Modelling Approach

Numerical simulations based on finite element modelling are increasingly being developed to accurately evaluate the tensile properties of GLARE (GLAss fibre REinforced aluminium laminates). In this study, nonlinear tensile behaviour of GLARE Fibre Metal Laminates (FML) under in-plane loading conditions has been investigated. An appropriate finite element modelling approach has been developed to predict the stress–strain response and deformation behaviour of GLARE laminates using the ANSYS finite element package. The finite element model supports orthotropic material properties for glass/epoxy layer(s) and isotropic properties with the elastic–plastic behaviour for the aluminium layers. The adhesion between adjacent layers has been also properly simulated using cohesive zone modelling. An acceptable agreement was observed between the model predictions and experimental results available in the literature. The proposed model can be used to analyse GLARE laminates in structural applications such as mechanically fastened joints under different mechanical loading conditions.     

Structure and Properties of “Magnesium Alloy – Carbon Nanotubes” Nanocomposite and their Optimization Using Design of Experiments

Metal Science and Heat Treatment - A nanocomposite obtained by introduction of carbon nanotubes into the surface layer of magnesium alloy AZ31B by the method of friction stir processing is studied....     

A novel numerical modeling paradigm for bio particle tracing in non-inertial microfluidics devices

Microsystem Technologies - In this work, we report on the design and implementation of a new method for the two dimensional (2D) simulation of rigid spherical particles trajectory which are to be...     

Assessment of porosity of mortar using ultrasonic Rayleigh waves

The relationship between Rayleigh wave velocity at ultrasonic frequencies and porosity is investigated in dry and fully saturated mortar. Porosity is varied by changing the water/cement ratio. Rayleigh wave (RW) pulse velocity is measured accurately using air-coupled ultrasonic transducers as transmitter and receiver. The experimental results are compared with two single-phase models. Due to relatively weak correlation between RW velocity and porosity, measured data and the models are compared using statistical hypothesis tests. Although the parameters of the model are not accurately predicted, these tests conclude on a reasonable agreement between measured data and the models. This result can be useful to develop simplified models of wave propagation in concrete, or to estimate porosity in concrete cover from ultrasonic measurements.     

A new synthetic loading for large induction machines with no feedback into the power system

Full-load testing of large induction machines is constrained by the limitations in the power-supply and loading equipment of the manufacturer's facilities, resulting in costly set up time. A new synthetic loading method is proposed based on a bang-bang phase control strategy. The rated power oscillation created is routed to an auxiliary system and the source hydro has to provide only the total losses of the system, without seeing the excessive power swings observed in other synthetic loading techniques. In this technique, only induction machines are used which would enable motor manufacturers to build the test rig in-house. The control stage is very simple to implement and requires only unregulated DC supplies for the excitation windings. The method is suitable for any induction machine and does not requires any set up time. It is possible to strictly maintain constant DEFINE RMS voltage and current at rated values for the duration of the heat runs.     

Assessing the effect of surface chemistry on gold nanorod uptake, toxicity, and gene expression in mammalian cells

Through the use of various layer-by-layer polyelectrolyte (PE) coating schemes, such as the common poly(diallyldimethylammonium chloride)-poly(4-styrenesulfonic acid) (PDADMAC-PSS) system, the mammalian cellular uptake of gold nanorods can be tuned from very high to very low by manipulating the surface charge and functional groups of the PEs. The toxicity of these nanorods is also examined. Since the PE coatings are individually toxic, the toxicity of nanorods coated in these PEs is measured and cells are found to be greater than 90% viable in nearly all cases, even at very high concentrations. This viability assay may not be a complete indicator of toxicity, and thus gene-expression analysis is used to examine the molecular changes of cells exposed to PDADMAC-coated nanorods, which enter cells at the highest concentrations. Indicators of cell stress, such as heat-shock proteins, are not significantly up- or down-regulated following nanorod uptake, which suggests that PDADMAC-coated gold nanorods have negligible impact on cell function. Furthermore, a very low number of genes experience any significant change in expression (0.35% of genes examined). These results indicate that gold nanorods are well suited for therapeutic applications, such as thermal cancer therapy, due to their tunable cell uptake and low toxicity.     

Application of different CFD multiphase models to investigate effects of baffles and nanoparticles on heat transfer enhancement

In this work, the effect of baffles in a pipe on heat transfer enhancement was studied using computational fluid dynamics (CFD) in the presence of Al₂O₃ nanoparticles which are dispersed into water. Fluid flow through the horizontal tube with uniform heat flux was simulated numerically and three dimensional governing partial differential equations were solved. To find an accurate model for CFD simulations, the results obtained by the single phase were compared with those obtained by three different multiphase models including Eulerian, mixture and volume of fluid (VOF) at Reynolds numbers in range of 600 to 3000, and two different nanoparticle concentrations (1% and 1.6%). It was found that multiphase models could better predict the heat transfer in nanofluids. The effect of baffles on heat transfer of nanofluid flow was also investigated through a baffled geometry. The numerical results show that at Reynolds numbers in the range of 600 to 2100, the heat transfer of nanofluid flowing in the geometry without baffle is greater than that of water flowing through a tube with baffle, whereas the difference between these effects (nanofluid and baffle) decreases with increasing the Reynolds number. At higher Reynolds numbers (2100–3000) the baffle has a greater effect on heat transfer enhancement than the nanofluid.     

Oxytetracycline nanosensor based on poly-ortho-aminophenol/multi-walled carbon nanotubes composite film

Poly-ortho-aminophenol (PoAP) and multi-walled carbon nanotubes (MWCNTs) were deposited on the platinum electrode using cyclic voltammetry technique to form the Pt/PoAP/MWCNTs nanosensor for the electrochemical determination of oxytetracycline as analyte. This electrochemical nanosensor with good uniformity and high surface area was prepared in the presence of an ionic surfactant (sodium dodecyl sulfate) as electrolyte to suspend carbon nanotubes within the PoAP and improve the stability and electroactivity of the composite film. The surface morphology of the prepared nanosensor was characterized by scanning electron microscopy and showed a three-dimensional network structure. The influence of several parameters such as number of potential cycles, scan rate and pH of the solution on the electrochemical response of the resultant electrode was investigated. The prepared electrode functioned as a selective recognition element for oxytetracycline determination. It showed excellent electrochemical response to oxytetracycline at low oxidative potential in buffer solution of pH 2.0, with good stability and sensitivity. Under the optimal experimental conditions, the electrochemical response of the sensor was linear with respect to the concentration of oxytetracycline in a dynamic range of 0.2 μM–0.25 mM. The detection limit of the fabricated nanosensor was calculated as 0.10 μM (signal/noise = 3). This sensor was used successfully for the oxytetracycline determination in real samples with recoveries of 96.9–103.5 %.     

Nonlinear vibration and rippling instability for embedded carbon nanotubes

Based on the rippling deformations, a nonlinear continuum elastic model is developed to analyze the transverse vibration of single-walled carbon nanotubes (SWCNTs) embedded on a Winkler elastic foundation. The nonlinear natural frequency has been derived analytically for typical boundary conditions using the perturbation method of multi-scales. The results indicate that the nonlinear resonant frequency due to the rippling is related to the stiffness of the foundation, the boundary conditions, the excitation load-to-damping ratio, and the diameter-to-length ratio. Moreover, the rippling instability of carbon nanotubes, as a structural instability, is introduced and the influences of several effective parameters on this kind of instability are widely discussed.     

A fuzzy based multi-objective path planning of construction sites

Movement of materials, plant and site operative from one place to another on construction sites and construction workplaces are of paramount importance to site planners as savings in travel distance can reduce cost and increase productivity. In addition, risks on construction sites can be reduced if the use of vehicles and mobile plant is properly managed by setting out paths avoiding high risks areas. The work reported in this paper presents a framework for supporting path planning analysis of construction sites based on multi-objective evaluation of transport cost, safety, and visibility. This paper investigates the use of fuzzy-based multi-objective optimisation approach in making a more informed strategic decisions regarding the movement path of people and vehicles on construction sites, and detailed decisions regarding travel distance and operational paths on workplaces, enabling site planners to examine paths scenarios that are subjected to a high degree of uncertainty and subjectivity.