利用面板的加速度响应反求出面板所受的载荷力时间历程,首先,开展测力墙面板在台车冲击载荷下的试验,建立有限元仿真模型得获得一条初始的载荷力时间曲线,然后在满足仿真与实验的测力面板加速度响应差异最小的目标下,采用遗传迭代算法优化反求出作用在测力面板的一条最优的力时间曲线.最后通过试验验证,说明采用反求方法获得的测力板所受的载荷具有较好的适用性,该方法可以推广到测量铁路车辆的用组合式测力墙测量大吨位碰撞力.

The crashworthy car-body is an important means to solve the train passive safety protection technology in many countries, while collision test is an important method to evaluate it. The contact areas and impact forces in rail vehicle collision tests are too large for existing load cell walls. In this paper, the effects of the sensor spacing (d), number of sensors (n) and faceplate thickness (h) on the load cell wall responds were evaluated, and a structure design scheme of large-tonnage load cell walls to combine independent-faceplate with holistic-faceplate was proposed. For the test requirements of a main energy-absorbing structure of subway vehicles, the structure design of large-tonnage load cell wall was carried out. By the trolley crash test, the magnitude and distribution of impact force of structure were obtained. Compared with the simulation results, the tendencies were consistent and a difference of less than 5%. The designed structure can meet engineering needs of large-tonnage impact force test of rail vehicles collision test.

This study proposes the design strategy of a new collapse zone structure for railway vehicles and explores its crashing performance through numerical simulation and experiments. Starting from the one-dimensional (1D) collision analysis of two train sets, the force-displacement characteristics of each vehicle-end can be expressed in the form of a non-linear spring and the energy absorption distribution for each vehicle interface was achieved. Then, the present paper moves on to the three-dimensional (3D) finite element analysis (FEA) for the detail design of the collapse zone structure which primarily consists of front beams, rolled hollow sections (RHSs), channels and collapse initiators. The 3D resultant force-displacement response matches well with 1D characteristics. Additionally, the energy absorption of 3D computation is larger than the required value. Finally, dynamic impact tests were conducted to validate the crashworthiness of the designed energy-absorbing structure. The results showed that all the critical indicators are within 10% of both methods, which satisfies the correlation requirements of EN15227. The deformed shapes are also comparable and with reasonable agreement between the test outcomes and FEA predictions. Therefore, the design strategy is well performed and the new designed collapse zone structure is recommended as a potential absorber of impact energy.

Precast spandrel beams are often used on the perimeter of precast buildings to support the precast floor units. These elements are typically not considered part of the lateral force resisting system. However, the presence of the spandrel beams in the floor system may modify the strength, stiffness, and deformation capacity of the precast floor diaphragm. The nature of this response is highly dependent on the characteristics of the details connecting the spandrel to the precast floor system. These details are often welded connections used primarily for erection stability and designed without diaphragm action in mind. With emerging design methodologies for precast diaphragms requiring better-defined performance, the impact of the spandrel beams must be accounted for. Accordingly, analytical research is presented here that examines the effect of spandrel-beam-connecting details on the global characteristics and local demands of a flexure-controlled precast floor diaphragm. Design recommendations are provided.

The Tevatron is a proton anti-proton accelerator collider operating at the Fermi National Accelerator Laboratory. The machine is currently delivering beam for the CDF and DO experiments, which expect increasing luminosity until the conclusion of Run II, planned for 2009. The laboratory defined a plan for achieving higher luminosity, and one of the tasks is the upgrade of the accelerator's beam position monitor (BPM). The Tevatron was built during the early eighties and some of its control systems, including the BPMs, are still the original ones. This paper describes the front-end software of the Tevatron BPM upgrade, from the requirements to the implementation, and the underlying hardware setup. The front-end software designed is presented, emphasizing its modularity and reusability, allowing it to be applied to other Fermilab machines

Results from multidimensional numerical simulations and cycle simulations are presented in an effort to optimize the performance of a fuel-lean-burn, homogeneous charge, natural gas spark-ignition internal combustion (IC) engine. The multidimensional numerical simulations are performed using modified versions of the KIVA-2 and KIVA-3 computer codes. The engine cycle simulations are performed using the WAVE code. The KIVA codes are enhanced with a turbulent combustion submodel which employs a two-step, natural gas/air chemical kinetics scheme with a temperature-dependent activation energy, together with a modified eddy dissipation model to treat the effects of turbulence on the burning rate. The output from the multidimensional calculations is used, in a novel way, as input to the WAVE cycle simulation code to predict overall engine performance. The Caterpillar G3400 and G3500 fuel-lean-burn natural gas engines are the specific engines under study. The predictions for brake specific fuel consumption (BSFC) are within 1% of the measured values for all cases where engine data are available. The effects of swirl, combustion chamber geometry, and spark location on burning rate and BSFC are investigated. Specifically, the results show that: (1) the numerical predictions are in good qualitative and quantitative agreement with engine data; (2) there is an optimum initial swirl ratio for the central bowl, central spark plug geometry; (3) an offset bowl results in a lower BSFC than a central bowl for the same initial swirl ratio and spark plug location; and (4) an offset spark plug results in a lower BSFC than a central plug for the same initial swirl ratio.

Combustion of a swirling, stoichiometric, and homogeneous mixture of natural gas and air in a short cylindrical chamber has been studied experimentally and simulated numerically. Each mixture was given a steady-state swirling motion by a rotating roughened disc before being ignited at the center of the chamber. By using discs of differing roughness and by varying the disc speed, the intensities of swirl and turbulence could be varied independently so that the effects on combustion of mixture turbulence and swirl-induced buoyancy could be separately examined. Combustion rate and overall chamber heat transfer were inferred from chamber pressure-time records. High-speed schlieren photography showed the effect of swirl on the early flame kernel. With given swirling angular momentum, increased turbulence level always reduced burning duration and increased total heat transfer rate. With given turbulence level, increasing the swirl intensity from zero first decreased, then strongly increased, the burning duration. The swirling Reynolds number (based on chamber radius and peak tangential velocity) at which combustion duration was minimized was in the range 30,000–40,000. At high Reynolds number buoyancy forces appear to have a strongly inhibiting effect on flame propagation.

This document contains the design for the BPM/BLM upgrade data acquisition software. The proposed design defines a general BPM framework that can be used on other similar BPM projects across the laboratory. A specialization of the framework provides the functionality necessary to meet the requirements of the Tevatron BPM upgrade project.