Search results for "composite"
showing 10 items of 4584 documents
Influence of mechanical properties of the sheet material on formability in single point incremental forming
2004
Abstract New trends in sheet metal forming are rapidly developing and several new forming processes have been proposed to accomplish the goals of flexibility and cost reduction. Among them single point incremental forming operations, in which the final shape of the component is obtained by the relative movement of a simple and small punch with respect to the blank, appear quite promising. In the paper, material formability issues in incremental forming were studied. Some relevant correlations among material formability and other mechanical properties of the material were analysed. The FLD 0 value, i.e. the major strain at fracture in plane strain conditions, was determined for different mat…
The future use of structural composite materials in the automotive industry
2007
The automotive industry's use of structural composite materials began in the 1950s. Since those early days, it has been demonstrated that composites are lightweight, fatigue resistant and easily moulded to shape in other words, a seemingly attractive alternative to metals. However, there has been no widespread switch from metals to composites in the automotive sector. This is because there are a number of technical issues relating to the use of composite materials that still need to be resolved including accurate material characterisation, manufacturing and joining. This paper reports the findings of a recent European initiative that examined the future use of composite materials in the aut…
Float zone single crystals for testing rods, pulled under electron beam heating
2019
Electric Field Effect on the Thermal Decomposition and Co-combustion of Straw with Solid Fuel Pellets
2019
The aim of this study was to provide more effective use of straw for energy production by co-firing wheat straw pellets with solid fuels (wood, peat pellets) under additional electric control of the combustion characteristics at thermo-chemical conversion of fuel mixtures. Effects of the DC electric field on the main combustion characteristics were studied experimentally using a fixed-bed experimental setup with a heat output up to 4 kW. An axisymmetric electric field was applied to the flame base between the positively charged electrode and the grounded wall of the combustion chamber. The experimental study includes local measurements of the composition of the gasification gas, flame tempe…
Numerical study of two-dimensional wet foam over a range of shear rates
2017
The shear rheology of two-dimensional foam is investigated over a range of shear rates with the numerical DySMaL model, which features dynamically deformable bubbles. It is found that at low shear rates, the rheological behavior of the system can be characterized by a yield stress power-law constitutive equation that is consistent with experimental findings and can be understood in terms of soft glassy rheology models. At low shear rates, the system rheology is also found to be subject to a scaling law involving the bubble size, the surface tension, and the viscosity of the carrier fluid. At high shear rates, the model produces a dynamic phase transition with a sudden change in the flow pat…
Anomalous wave structure in magnetized materials described by non-convex equations of state
2014
Agraïments: Institute for Pure and Applied Mathematics (UCLA) 2012 program on "Computational Methods in High Energy Density Plasmas. We analyze the anomalous wave structure appearing in flow dynamics under the influence of magnetic field in materials described by non-ideal equations of state. We consider the system of magnetohydrodynamics equations closed by a general equation of state (EOS) and propose a complete spectral decomposition of the fluxes that allows us to derive an expression of the nonlinearity factor as the mathematical tool to determine the nature of the wave phenomena. We prove that the possible formation of non-classical wave structure is determined by both the thermodynam…
Enhancement of heat exchanger thermal hydraulic performance using aluminum foam
2018
Abstract This paper deals with an experimental study of a turbulent forced convection in a rectangular channel partly fitted with aluminum metallic foam blocks. Experiments were carried out on samples having a constant porosity of 93.8%, different grades of 5, 20 and 40 PPI, and three different height ratios of 0.6, 0.8 and 1. The blocks were arranged in a baffle like configuration. A constant heat flux of 2 W/cm2 was applied on the bottom wall of the test section, while air velocity was varied from 1 to 5 m·s−1. Temperatures of the wall along the flow direction as well as those of the inlet and outlet sections have been measured. Additionally, pressure drop measurements across the aluminum…
Gold nanoclusters for ratiometric sensing of pH in extremely acidic media.
2019
AuNCs capped with β-nicotinamide adenine dinucleotide phosphate exhibit an outstanding performance as fluorescent pH sensors; specifically they exhibit a high emission in strongly acidic media and linear dependence on pH in extremely acidic media (0.6–2.7) as well as in the 7.0–9.2 pH range, while they are unresponsive at intermediate pH values. Remarkably, these AuNCs make ratiometric sensing possible in extremely acidic media with a single fluorophore, specifically the nanocluster itself.
Friction Stir Welding Of AA6082-T6 Sheets: Numerical Analysis And Experimental Tests
2004
3D numerical simulation of the Friction Stir Welding process is developed with the aim to highlight the process mechanics in terms of metal flux and temperature, strain and strain rate distributions. The numerical results have been validated though a set of experimental tests.