4,801 research outputs found
Crash tests of tension bolts in light safety collision devices
No full textThis paper demonstrates the jig set for the crash test and the crash test results of the tension bolts with respect to an applied pre-tension. The tension and shear bolts are adopted at Light Collision Safety Devices as a mechanical fuse when tension bolts reach designed failure load. The kinetic energy due to the crash is absorbed by secondary energy absorbing devices after the fracture of tension bolts. One tension bolt was designed to be failed at the load of 375 kN. The jig set was designed to convert a compressive loading to a tensile loading and installed at the high speed crash tester. The strain gauges were attached at the parallel section of the tension bolts to measure the level of the pre-tension acting on the tension bolts. Crash tests were performed with a barrier whose mass was 250 kg and initial speed of the barrier was 9.5 m/sec. The result includes the load response of the tension bolts during both the crash tests and finite element analysis
Crash Tests of Tension Bolts in Light Safety Collision Devices
No full textThis paper demonstrates the jig set for the crash test and the crash test results of the tension bolts with respect to an applied pre-tension. The tension and shear bolts are adopted at Light Collision Safety Devices as a mechanical fuse when tension bolts reach designed failure load. The kinetic energy due to the crash is absorbed by secondary energy absorbing devices after the fracture of tension bolts. One tension bolt was designed to be failed at the load of 375 kN. The jig set was designed to convert a compressive loading to a tensile loading and installed at the high speed crash tester. The strain gauges were attached at the parallel section of the tension bolts to measure the level of the pre-tension acting on the tension bolts. Crash tests were performed with a barrier whose mass was 250 kg and initial speed of the barrier was 9.5 m/sec. The result includes the load response of the tension bolts during both the crash tests and finite element analysis
Characterization of dynamic tensile and shear strength of safety bolts in light collision safety devices of a train
No full textThis paper introduces design strategy to develop safety bolts in the light collision safety devices under dynamic tensile and shear loading conditions. The light collision safety device is an energy absorbing one for low speed collision of a train. An energy absorbing scenario in the device has several sequential stages. Tension and shear bolts are the key components which make the sequential energy absorbing scenario operated by a series of failures at the specific collapse load. Exact failure loads of tension and shear bolts at crash conditions were determined in aid of finite element analysis considering the dynamic material properties of component materials. Failure loads of tension and shear bolts designed were verified with experiments using tension and shear type jig sets at quasi-static and dynamic loading conditions. Strain gages were attached to both the parallel section of tension bolts to measure the load response acting on tension bolts and the jig set to measure the load responses acting on shear bolts. The quasi-static and dynamic experiments as well as the numerical analysis explained above predicted the load capacities of tension and shear bolts accurately for the crashworthiness design
Travels in Mesopotamia including a journey from Aleppo to Bagdad, by the route of Beer, Orfah, Diarbekr, Mardin, and Mousul; with researches on the Ruins of Nineveh, Babylon, and other ancient cities. By J.S. Buckingham, author of Travels in Palestine an
No full textPreface: By Buckingham, J.S.Appendix.Dedication: by the author to Lady Hester Lucy StanhopeContent description: TitleIllustration: 14 (Views ,varia ,)Pagination: pp20+479p, pp4+538pVolumes: 2Text Genre:ProseIllustration: 14 (τοπία ,άλλα θέματα ,
Detecting photoelectrons from spontaneously formed excitons
No full textExcitons, quasiparticles of electrons and holes bound by Coulombic attraction, are created transiently by light and play an important role in optoelectronics, photovoltaics and photosynthesis. They are also predicted to form spontaneously in a small-gap semiconductor or a semimetal, leading to a Bose?Einstein condensate at low temperature, but there has not been any direct evidence of this effect so far. Here we detect the photoemission signal from spontaneously formed excitons in a debated excitonic insulator candidate, Ta2NiSe5. Our symmetry-selective angle-resolved photoemission spectroscopy reveals a characteristic excitonic feature above the transition temperature, which provides detailed properties of excitons, such as the anisotropic Bohr radius. The present result provides evidence for so-called preformed excitons and guarantees the excitonic insulator nature of Ta2NiSe5 at low temperature. ? 2021, The Author(s), under exclusive licence to Springer Nature Limited.11Nsciescopu
Development of Super Insulator with Staggered Beam
No full textThe thermal conductivity of a vacuum insulation panels(VIPs) is investigated theoretically for the development of super insulator. A staggered beam model, a design subject to the atmospheric pressure, is suggested. To design core structure, analyses of strength and heat conduction are performed. Deflection effect by the atmospheric pressure is also considered. Finally, the effective thermal conductivities are calculated for various materials. The insulation performance of the proposed model can be enhanced by taking materials of greater figure of merit,σ /k. In addition, core structure on which the maximum stress is uniformly distributed is the most desirable
Thermochemical design of a micro liquid monopropellant rocket with catalytic reaction of hydrogen peroxide
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