Brillouin-scattering Optical Time Domain Reflectometry (BOTDR) is a viable technology for simultaneous, distributed strain and temperature measurements for miles-long transportation structures. It is a promising tool to ensure the smooth operation and safety of bridge structures that are key links in surface transportation networks or between various transportation modes: i.e., from airport to train station. Currently, telecom-grade optical fibers are widely used in civil engineering for strain and temperature measurements. These fibers are very fragile and easy to break during installation and measurement. In order to understand the ultimate behavior of structures, more rugged optical fibers such as carbon/polyimide coated fibers were recently proposed. One laboratory study on two single fibers indicated that new carbon/polyimide coated fibers can sustain a maximum strain of up to 4, which can survive any local crack in concrete members or buckling in steel members once they are installed on the structural members. This project aimed to characterize the ruggedness and signal loss of various packaged optical fibers and validate their performance as sensors. Among the tested optical fibers, bare single-mode fibers (SMF-28) with uncoated anchoring have the lowest shear strength and the lowest ultimate strain under tension, and are thus not suitable to apply in harsh environments. Polyimide-coated optical fibers have the highest shear strength and the highest ultimate strain under tension, making them the best candidate for civil infrastructure applications. Both glass fiber reinforcing polymer (GFRP) and carbon coated optical fibers are sufficiently rugged to be applied to civil infrastructure.

关键词：钢铁;光纤;应变测量;交通安全;桥梁

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关键词：钢铁；形状记忆合金；执行器；二元合金

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The relative armor penetration ability of different kinds of projectiles is of general interest from both offensive and defensive viewpoints in law enforcement and military applications. This paper presents data on armor penetration of four different projectile types (all in 5.56mm NATO) on both 6.35mm thick steel plate (A36) and proprietary glass/aramid composite armor. The bullet penetrating steel plate most readily was the M855 bullet which has a steel penetrator core. This bullet had a V50 of 1992 ft/s. The second best penetrating bullet in steel plate was the jacketed lead core M193 bullet with a V50 of 2240 ft/s. The solid copper bullet had a much higher V50 in the steel plate at 2514 ft/s. The solid brass bullet was the worst penetrator in the group with a V50 of 2612 ft/s in the steel plate. The relative penetration ability was different in the composite armor. The best penetrator was once again the M855 bullet with a V50 of 1945 ft/s. However, the second best penetrator was the solid brass bullet with a V50 of 2868 ft/s. The third best penetrator was the solid copper bullet with a V50 of 2960 ft/s. The worst penetrating bullet in the composite armor was the jacketed lead core M193 bullet with a V50 of 3049 ft/s.

关键词：钢铁；合装甲；装甲；黄铜；铜

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Starting about 1920 it becomes easier to track the growth of bearing materials technology. Until 1955, with few exceptions, comparatively little progress was made in this area. AISI 52100 and some carburizing grades (AISI 4320, AISI 9310) were adequate for most applications. The catalyst to quantum advances in high-performance rolling-element bearing steels was the advent of the aircraft gas turbine engine. With improved bearing manufacturing and steel processing together with advanced lubrication technology, the potential improvements in bearing life can be as much as 80 times that attainable in the late 1950s or as much as 400 times that attainable in 1940. This paper summarizes the chemical, metallurgical and physical aspects of bearing steels and their effect on rolling bearing life and reliability. The single most important variable that has significantly increased bearing life and reliability is vacuum processing of bearing steel. Differences between through hardened, case carburized and corrosion resistant steels are discussed. The interrelation of alloy elements and carbides and their effect on bearing life are presented. An equation relating bearing life, steel hardness and temperature is given. Life factors for various steels are suggested and discussed. A relation between compressive residual stress and bearing life is presented. The effects of retained austenite and grain size are discussed.

关键词：滚子轴承;残余应力；钢；硬度

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Rapidly deployable mobile bridges are of direct relevance to military and civilian agencies. The US Army uses such bridges in a broad range of applications including assault, tactical, and general communication. Civilian use extends from temporary infrastructure improvements during natural disasters to planned situations that are equally critical. This paper describes a modular bridge system developed primarily for use in assault scenarios where rapid deployment is vital, but this design concept is also relevant in civil applications. The robust metallic design of the bridge is based on an aluminum trussed arch reinforced by steel cables. The segmental form of the structure allows it to be folded into a compact package for transportation in a standard 40 ft container, which facilitates shipping by road, rail, sea, or air (C-130 transport aircraft). The bridge segments also facilitate adaptation of the bridge to different spans ranging from 8m to 32m. The load rating for these spans varies between 100T and 40T respectively. The preferred deployment approach for the assault configuration uses a scissor method in conjunction with a winching mechanism mounted on an auxiliary bridge guide. Compared to more conventional techniques, this method reduces the demands on the bridge launcher. The complete system provides an integrated solution to cover a broad spectrum of bridging applications. Extensive computer analysis was used to refine and optimize the components in the bridge. Structural testing of components during the design stage also helped guide the design process, and operational and load testing of a prototype system using strain gauging confirmed the integrity of the final design.

关键词：桥梁;结构特性;交通

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关键词：加强钢;钢筋;耐腐蚀涂料;搪瓷涂层

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No abstract available.

关键词：云物理；大气化学；气象雷达；地面站；通信网络

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Dual phase (DP) steels belong to the group of high-strength low-alloy (HSLA) steels. Our study focuses on the causes of crack formation of sheets, which are designed for deep drawing, of DP780-grade dual phase steel. Also, a series of heat treatment experiments were performed regarding the effect of intercritical annealing temperature on the structure and mechanical properties of the finished product (in this case a rolled sheet).

关键词：钢铁；双相钢；深冲；高强度低合金钢

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Replacement of the steel grating deck on the lift span of the Morrison Bridge in Portland, OR, will utilize glass fiber reinforced polymer (FRP) panels to address ongoing maintenance issues of the deteriorated existing deck, improve driver safety and introduce bridge water runoff treatment. This report outlines the testing methods and results of an experimental program aimed primarily at evaluating a new open cell deck. While most FRP panels are connected via shear studs that are grouted within isolated pockets, the panels in this case were bolted directly to the steel stringers. Two different FRP deck options were evaluated for comparison: one with open cells and the other with more conventional closed box extrusions. The objective was to evaluate the strength of the FRP to steel stringer connection with individual bolt connection tests, the strength and fatigue resistance of the FRP decks themselves, and the relative lateral stiffness contribution of the panels. Additional related tests were also included to complement the research effort such as the inclusion of tests on a closed box deck removed from the Broadway Bridge in Portland, OR, and strength tests of a retrofit attachment option of FRP deck to stringer using bolted clamps.

关键词：钢铁；桥面；纤维增强；玻璃纤维增强复合材料

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Since the introduction of Electroless (EL) coating in 1946 by Brenner and Riddle, the process has been the subject of steady growth. It is one of the most elegant methods available for the production of alloy coatings on surface. The technique involves the autocatalytic reduction, at the substrate/solution interface, of cations by EL bath released from suitable chemical reducing agents. EL coating technique is simple one, as can be manifested just by controlling pH and temperature of the coating bath. Such coatings are reported to provide excellent physical and mechanical properties. The electroless coatings are being studied at Indian Institute of Technology Roorkee since 1985. The structural and morphological behavior of Ni-P coatings for different phosphorous contents has been extensively studied. Sub-micron size coating islands and their transformations have been deduced. The metallography studies using hot stage within TEM to follow the phase transformations occurring at various temperatures have been studied for Ni-B EL coatings. The realization of mechanical bonding along with chemical bonding between EL coating and the substrate has been explained by coated copper on ceramic powder. As a forward step towards composite coatings, Ni-P-C, Ni-P-Al_2O_3, Ni-P-ZrO_2 has been developed by EL co-deposition technique. Ag-graphite coatings produced by EL technique exhibits nearly five times higher wear resistance and nearly two times better corrosion resistance apart from a good electrical conductor. The tribological behavior of electroless Ni-P-X and Ni-P coatings on steel and aluminium substrates in different conditions i.e., as coated, heat treated at various temperatures at different extents of time with different normal loads, have been studied in terms of dry sliding friction and wear against counter face of case hardened steel. In Ni-P-X nanocoating (X= ZrO-2-Al_2O_3-Al_3Zr), X has been produced in-situ and are of nano-size particles. Such coating could be done on carbon fibre of 7μ. diameter uniformly. Ni-P-ferrite nanocoatings with thickness less than nearly lmm thick, is exhibiting good absorption of microwave in the range of 12-18 GHz which can be exploited for radar applications. Micro-thickness coatings are paying ways to Nano coatings. Nanocoatings are the coatings in which either the thickness of the coating is in nano level or second phase that dispersed in the coat matrix is of nano-size. To further explore the field of EL nanocomposite coatings, now days, a work on EL Ni-P-ZnO, TiO_2, Al_2O_3, ZrO_2 and Ni-B-ZrO_2 for its mechanical properties has been carried out.

关键词：钢铁；化学发光（EL）；镍PX；纳米复合材料；加固

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