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Woodward P.K.,Heriot - Watt University | Laghrouche O.,Heriot - Watt University | Thomas S.,Airforce Technology
Civil-Comp Proceedings | Year: 2014

It is known that masonry arch bridges carry a lot of rail traffic in the UK; almost all of which have been in service for many years. However, they increasingly need to be maintained and hence their performance requires enhancement to ensure increased longevity. Arch structures were designed for lower vehicle loads than they are currently subjected to. Hence this work is focused on finding a new technique of extending the scope of a proven ballast strengthening technique (XiTRACK) to allow a better distribution of the loads from the trains. In this work a static 3D finite element analysis of a masonry arch railway bridge has been conducted to study the stabilizing effects on the bridge using polyurethane polymer. A moving load across the masonry arch was also analysed to detect critical loads of maximum stress applied to the arch. The results of the finite element analysis were calibrated and verified with actual data recorded on site from the Whiley Hill bridge located at Darlington. The work presented in this paper is based on a linear elastic analysis. Further simulations using non-linear plasticity analysis are currently being performed in combination with actual site measurement data to achieve more accurate results. © Civil-Comp Press, 2014.


Yin J.-P.,North University of China | Yao Z.-H.,North University of China | Yao Z.-H.,Airforce Technology | Wang Z.-J.,North University of China
Huozhayao Xuebao/Chinese Journal of Explosives and Propellants | Year: 2011

Numerical simulations by a ANSYS/LS-DYNA finite element software were carried out to research the influence of the parameters of liner on the forming of circumferential MEFP. By statistic analysis of the formed assembly EFP, the regulation of the curvature radius, thickness and caliber of the liner's influence to the forming of circumferential MEFP and the appropriate relatives among parameters were obtained. The result shows that the speed of the middle EFP formed by the circumferential MEFP is apparently larger than the marginal EFP under explosive loading. While the ratio of the curvature radius and the caliber of the liner vary from 0.9


Hsu C.-C.,Airforce Technology
Hangkong Taikong ji Minhang Xuekan/Journal of Aeronautics, Astronautics and Aviation, Series B | Year: 2011

Meshfree, adaptive and Lagrange-style smoothed particle hydrodynamics method was adopted to investigate the detonation processes of high explosives. The numerical results of one-dimensional cases were compared with analytical results based on classical C-J theory. Good consistence was found, thus the reliability of the present numerical model was proven. In the two-dimensional cases, detailed flow properties of slab explosives with and without leakage, were presented in the different explosive stages. During detonation processes, high explosives particles being gathered in leakage introduces a high energy density and high pressure region. Finally, the particles near by the region with high energy and high pressure will spread faster and form a jet. The pressure fields are definitely different in detonation and after detonation. After the detonation, the maximum pressure region is in the interior of flow and makes particles to expand without special direction. However, the maximum pressure region is close to the detonation wave and forces most particles to expand to stream-wise free edge during detonation.


Sabelkin V.,Airforce Technology | Misak H.E.,Wichita State University | Mall S.,Airforce Technology | Asmatulu R.,Wichita State University | Kladitis P.E.,Airforce Technology
Carbon | Year: 2012

The mechanical behavior of four carbon nanotube (CNT) wires, comprised of 1-yarn, 30-yarn, 60-yarn, and 100-yarn, was investigated under constant tension at two loading rates of 0.02 mm/s and 2 mm/s. Tests were conducted with both as-fabricated and pre-stressed wires. The ultimate tenacity or apparent ultimate tensile strength of all four wires was found to be independent of loading rate, with those for the single-yarn wire about twice those of the multiple-yarn wires. Strain at a given stress level and failure strain of the multiple-yarn wires before pre-stressing were almost an order of magnitude larger than those for the single-yarn wire, and this difference was reduced considerably after pre-stressing. The failure mechanisms of 1-yarn wire or twisted individual yarns in multiple-strand wires involved ductile (necking) deformation and fibrillar breakage. Inner yarns in multiple-yarn wires initially failed at the same location, followed by outer yarns failing at different locations. Additionally, sliding occurred between individual yarns, and twisting of the yarns accompanied by surface wear took place in the multiple-yarn wires, which contributed to their failure at a lower load compared to the single-yarn wire.


Pakistan and China are jointly producing the JF-17B dual seat combat fighter aircraft to be inducted by the Pakistan Air Force (PAF).Production of the multi-role combat aircraft was announced at an induction ceremony held at Chengdu Aerospace Corporation (CAC) Chengdu, China ...


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Elbit completes night flight demonstrations of digital eye piece Elbit Systems has successfully completed a series of night. Pratt & Whitney wins $1 ...


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Lockheed receives $504.3m to support RCAF's C-130J Super Hercules fleet 8 July 2016 Lockheed Martin will continue to provide in-service support (ISS) for the Royal Canadian Air Force's (RCAF) C-130J Super Hercules fleet, under a $504 ...


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