Energy absorption of aluminum foam filled braided stainless steel tubes under quasi-static tensile loading conditions

A theoretical model to predict the energy absorption capabilities of aluminum foam filled braided stainless steel tubes under tensile loading conditions has been developed and is presented. Experimental testing was completed on braided tubes, with a nominal diameter of 64.5 mm and woven from 304 stainless steel wires with a diameter of 0.51 mm, filled with rectangular prisms of closed cell aluminum foam with densities ranging from 248 to 373 kg/m³. Based upon observations from experimental testing and applying a unit cell concept to the braided tube, a theoretical model which incorporates two stages of deformation was developed. Within the first stage of deformation, which occurs prior to tow lockup of the braided tube, energy absorption is primarily due to compression of the aluminum foam core. After tow lockup has occurred the energy absorption behavior of the assembly is a sole result of the deformation of the braided tube. Comparisons between the energy absorption predictions of the analytical model and experimental observations were found to be in good agreement for assembly lengths of approximately 400 mm. For the tensile loading conditions and geometry of aluminum foam filled braided tubes considered in this research energy absorption ranged from approximately 5.2 to 7.9 kJ with corresponding tube elongations of 400 mm.     

Rapid and cost-effective manufacturing of high-integrity aerospace components

This paper presents a comprehensive set of theoretical investigations and industrial applications of computer-based rapid manufacturing technology for high-integrity aerospace components. Two rapid manufacturing processes have been proposed by integrating rapid prototyping, high-speed machining (HSM), reverse engineering and geometric computation theory. They have been validated through trial manufacturing of a matrix of current aerospace components embracing critical design features to be found across the aerospace industry. Applied to future development programmes, this research will provide aerospace companies the benefits of significant decrease in product introduction lead-time, savings in non-recurring product introduction costs and considerable reduction in manufacturing costs for “one off” and low volume service parts. The findings can also be applied to rapid prototype development in other industries, such as automotive and military.     

Modelling the regional economic effects of the Danish Great Belt link

Different approaches to modelling the impact of transport infrastructure investment on regional economic development are examined, including production function and economic potential approaches. An integrated modelling approach involving both transport costs and models of regional and interregional economic structure is advocated. This approach is applied to the question of forecasting the regional economic effects of the Danish Great Belt link, a major Danish infrastructure investment, due to open in 1997. These effects are shown to be modest.     

Thermal Behaviour of HMX/RDX Mixtures

Thermal behaviour of HMS/RDX mixtures is studied by differential thermal analysis (DTA) and thermogravimetric analysis (TGA). It has been found that the temperature of polymorphic transformation of HMX shows an increase due to the presence of RDX. The enthalpies of the enothermic transformations depend on the composition of the mixture, and up to 30% RDX there is a linear relationship. The formation of an eutectic with a composition of 30/70 (HMX/RDX) is postulated to explain the melting processes.     

Nanoelectromagnetics: Circuit and Electromagnetic Properties of Carbon Nanotubes

This Review presents a discussion of the electromagnetic properties of nanoscale electrical conductors, which are quantum mechanical one‐dimensional systems. Of these, carbon nanotubes are the most technologically advanced example, and are discussed mainly in this paper. The properties of such systems as transmission electron microscopy waveguides for on‐chip signal propagation and also the radiation properties of such systems are discussed. This work is primarily aimed at microwave, nanometer‐wave, and THz electronics. However, the use of nanotubes as antennas in the IR and optical frequency range is not precluded on first principles and remains an open research area.

     

Self-latching operation of MOBILE circuits using series-connection of RTDs and transistors

One of the most attractive features of MOBILE-based circuits is their self-latching operation, which allows pipelining at the gate level, and thus very high through-output, without any area overhead associated to the addition of the latches. However, the self-latching behavior is not inherent to the practical circuit topologies employed to implement MOBILE circuits. This paper reports on very simple MOBILE structures supporting this statement. The analysis performed is useful in extracting design guidelines to guarantee the required behavior.     

Patterned Arrays of Supramolecular Microcapsules

Micropatterning of hydrogel has brought innovative outcomes in fundamental and applied material sciences. Previous approaches have mainly been dedicated to fabricate arrays of bulk hydrogel beads, which have inherent challenges including loading ability, scalability, specificity, and versatility. Here, a methodology is presented to create hollow microcapsule arrays from sessile microdroplets. The difference in wettability between hydrophilic and hydrophobic surfaces enables self‐partitioning of liquid into microdroplet arrays, serving as microreservoirs to load complementarily functionalized host–guest polymers, cucurbit[8]uril‐threaded highly branched polyrotaxanes (HBP‐CB[8]) and naphthyl‐functionalized hydroxyethyl cellulose (HEC‐Np). The interfacial dynamic complexation between positively charged HBP‐CB[8] and HEC‐Np occurs in the presence of negatively charged surfactants, resulting in condensed supramolecular hydrogel skins. The hydrogel microcapsules are uniform in size and are developed to encapsulate target cargos in a robust and well‐defined manner. Moreover, the microcapsule substrates are further used for surface enhanced Raman spectroscopy sensing upon loading of gold nanoparticles. This facile assembly of microcapsule arrays has potential applications in controlled cargo delivery, bio‐sensing, high‐throughput analysis, and sorting.