Total Vehicle Weight Research Articles

Design and calculation of a railway car composite roof under concrete cube crash

Nowadays, a major issue in transportation is weight reduction. This paper deals with weight reduction of about 3.5% over the total weight of a railway vehicle by substituting an aluminium roof with a composite material design. The design was done by static calculations, and this paper deals with the RSSB Standard GMRT 2100 requiring a roof sufficiently strong to resist the penetration into the vehicle of a concrete cube weighing 100 kg dropped from a height of 3.0 m above the roof at 300 km/h. Calculations are carried out by the finite analysis method. Both aluminium and composite roofs are compared.

Design and Characteristic Analysis of Hybrid-Type Levitation and Propulsion Device for High-Speed Maglev Vehicle

This paper deals with the design and characteristic analysis of electro-magnet/permanent-magnet (EM-PM) hybrid levitation and propulsion device for high-speed magnetically levitated (maglev) vehicle. The machine requires PMs with high coercive force in order to levitate the vehicle by only PMs, and propulsion force is supplied by long-stator linear synchronous motor (LSM). The advantages of this configuration are an increasing levitation airgap length and decreasing total weight of the vehicle, because of the zero-power levitation control. Several design considerations such as machine structure, manufacturing, and control strategy are described. Moreover, the levitation and propulsion device for high-speed maglev vehicle has been designed and analyzed usign the electromagnetic circuit and FE analysis. In order to verify the design scheme and feasibility of maglev application, 3-DOF static force test set is implemented and tested. The obtained experimental data using the static tester shows the validity of the design and analysis approaches.

Study of impact energy propagation phenomenon and modal characteristics of an armored vehicle undergoing high velocity impact

A new manufacturing technology is being employed to build a new type of armored vehicle. While thick panels are welded together in the old manufacturing technology, relatively thin panels are welded to a frame structure in the new manufacturing technology. The structural integrity of the new type of armor vehicles can be maintained mainly by the frame structures while the panel thickness is reduced significantly to reduce the total vehicle weight. Since the dynamic characteristics of a frame-panel hybrid structure are different from those of the old type of structure which consists of only thick panels, they should be identified to achieve a good performance of the vehicle. For this purpose, a proper FE model of the hybrid type of structure needs to be developed. In the present study, FE models are proposed to represent the frame-panel hybrid type structure efficiently. The impact energy propagation, the transient response and the modal characteristics are investigated with the FE models.

Nano-crystalline P/M aluminium for automotive applications

The reduction of total vehicle weight and lowering of moving masses within the engine are key elements to overcome future emission challenges of the automotive industry. Within a German BMBF funded project the melt spinning technology will be driven to a series production status. The very fast cooling condition of the melt leads to a nano-structure of the aluminium material. This results in new material properties of known alloys. The strength increases dramatically without lowered forming behaviour. With this process the freedom of designing complex alloys is very flexible. Different alloys have been investigated for several applications, where high strength at room and elevated temperatures and/or high wear resistance is required. This paper presents some results regarding the processing, microstructure and mechanical properties of a developed Al-Ni-Fe alloy. This joined research project with partners from the automotive industry as well as automotive suppliers and universities is funded by the German BMBF "NanoMobile" Program under Project number 03X3008.

Subsoil properties and cereal growth as affected by a single pass of heavy machinery and two tillage systems on a Luvisol

AbstractCompared to moldboard plowing, conservation tillage is frequently discussed to alleviate soil stresses caused by high wheel loads and, thus, decrease the risk of subsoil compaction. On a Luvisol derived from loess (Göttingen, Lower Saxony, Germany), a wheeling experiment was conducted in two contrasting tillage systems (continuous moldboard plowing [MP] 30 cm deep and shallow mixing [SM] 10 cm deep). A six‐row self‐propelled sugar beet tanker harvester (SBH 6: 34–36 Mg total vehicle weight, 8–11 Mg wheel load, 92–143 kPa calculated ground‐contact pressure) was used for a single pass. Each crop of the sugar beet–cereal–cereal rotation was cultivated with light experimental machinery on one of three adjacent fields each year. In October 2001 (Field 2), 2002 (Field 1), and 2003 (Field 3) wheeling with the SBH 6 was carried out on half of every tillage plot (soil moisture 70%–100% field capacity) after the harvest of previous sugar beet. Subsequently, the soil was tilled according to the respective treatment, and winter wheat, spring wheat, and spring barley were grown on Field 2, 1, and 3, respectively. During the following spring and summer, soil and plant measurements were conducted. Soil penetration resistance (10–25 cm) increased, and root length density of spring wheat decreased in SM tillage compared to MP tillage. At 40–45 cm depth, air‐filled pore volume at 6.2 kPa water tension (two fields), air permeability, and total pore volume (one field) were higher in SM than in MP treatments, respectively. Wheeling slightly increased penetration resistance in 15–25 cm depth but had no effect on any parameter measured at 40–45 cm soil depth. Generally, treatment effects on cereal‐grain yield were small and insignificant. Our results suggest that a single pass with a SBH 6 is unlikely to cause pronounced subsoil‐structure degradation on a loessial soil under moderate climatic conditions.

Fluid–structure interaction modeling of ringsail parachutes

In this paper, we focus on fluid–structure interaction (FSI) modeling of ringsail parachutes, where the geometric complexity created by the “rings” and “sails” used in the construction of the parachute canopy poses a significant computational challenge. It is expected that NASA will be using a cluster of three ringsail parachutes, referred to as the “mains”, during the terminal descent of the Orion space vehicle. Our FSI modeling of ringsail parachutes is based on the stabilized space–time FSI (SSTFSI) technique and the interface projection techniques that address the computational challenges posed by the geometric complexities of the fluid–structure interface. Two of these interface projection techniques are the FSI Geometric Smoothing Technique and the Homogenized Modeling of Geometric Porosity. We describe the details of how we use these two supplementary techniques in FSI modeling of ringsail parachutes. In the simulations we report here, we consider a single main parachute, carrying one third of the total weight of the space vehicle. We present results from FSI modeling of offloading, which includes as a special case dropping the heat shield, and drifting under the influence of side winds.

Bring back the steel? The growth of plastics in automotive applications

The development of plastics has evolved from the use of natural materials to the use of chemically modified natural materials and, finally, to completely man-made molecules. Plastics continue to improve, to afford flexibility, high-impact, and strength. In automotive applications, plastics have increased in utilization to comprise approximately 10% of the total vehicle weight. They offer increased ductility, freedom from corrosion, and increased styling capability. Although plastics have had a remarkable impact on our culture, it is obvious that there is a price to be paid for their use. Plastics are almost too good, as they are durable when processed correctly, but easily damaged when utilized in the incorrect application. Plastics also degrade very slowly, making recycling mandatory. And finally, while plastics consume only 4% of the world’s oil production (petroleum is the raw material that is chemically altered to form commercial plastics), their cost hinges on the cost of petroleum. As petroleum prices increase, so too will the cost of plastic. In 2004, the higher price of plastic forced many plastic manufacturers out of business, and forced many automotive suppliers to look into alternative replacements. With publications such as USA Today reporting that current oil reserves will only last 40 years, scientists continue to seek cheaper alternatives to plastic. This article summarizes the history of commercial plastic development, with a focus on utilization of the materials in automotive applications. Damage criteria of plastic components, namely scratch, oxidative degradation, and impact, are discussed in relation to coatings and processing robustness. Environmental regulations, particularly in relation to recycling mandates, are explained. And finally, trends in alternative material development, including bioplastics, films, ceramic coatings, and nano-composites; are formulated.

Pavement Smoothness at Weigh-in-Motion Sites: Developing Specifications for the Long-Term Pavement Performance Program

Accurate traffic data are vital to the success of the Long-Term Pavement Performance (LTPP) program. To minimize dynamic motions and therefore improve the accuracy of traffic loading data at weigh-in-motion (WIM) scales, pavement smoothness specifications were developed to screen sites for excessive truck dynamic loading that exacerbates scale error beyond ASTM recommended tolerances. WIM scale error was related to pavement profile characteristics by using a large simulation study of the response of virtual trucks over measured profiles. A distribution of error was compiled over the truck population for steer axle, tandem axle, and total vehicle weight at each site. The error distributions were summarized by their 95th percentile absolute error levels. The error levels assigned to each site were then used as a correlation standard for the proposed roughness indices and for the selection of corresponding threshold values. Instead of a single index, two versions of the Butterworth filter were selected for use in the specifications. One addresses short-range roughness and the other long-range roughness. The shortand long-range WIM error indices were then statistically related to WIM scale error to set the threshold values. An overview is presented of the development of the pavement smoothness specifications, including indices and threshold values.

Laser welding of complex aluminium structures

Automotive manufacturing is making significant strides towards producing lighter but stronger vehicles. Developments in high strength steels and lightweight materials, especially aluminium, have contributed to these advances. The body shell contributes nearly 25% of a car's weight. Current predictions estimate the contribution of aluminium in a car to be of the order of 10% of the total vehicle weight, whereas the use of aluminium alloys in car body manufacture could lead to potential weight savings of up to 43%. The use of aluminium is expected to grow in body in white and tailored welded blank applications within the automotive sector. Complex joint configurations are encountered in spaceframe assembly. One such joint structure, which involves the welding of a rectangular section to a flat plate, has been considered in the work reported. Traditionally, a MIG welding solution would be adopted to manufacture such a joint. Work was performed to establish the feasibility of using laser welding to manufacture the component and to compare the laser and MIG processes. A fibre optic delivered Nd-YAG laser beam, manipulated with an articulated arm robot, was successfully used to weld the tube to the aluminium plate. Spatter free welds with no externally visible porosity were achieved and no cracking was observed in any weld cross-section examined. Mechanical tests indicated that the static strength of the laser welds was lower than that achieved by MIG welding, which is attributed to the lower load bearing area in the laser welded joints.

液水ポンプ・インデューサの可視化試験

Development of a high suction performance pump inducer is required for a high-performance rocket system to reduce total weight of a launch vehicle and to increase its reliability. It is very important for a high suction performance inducer design that the relation between flow patterns and cavitation structures makes clear. In this study, flow patterns observed with PIV system and cavitation structures observed with a high-speed camera are reported and discussed about their relationship.

B113ロケットポンプインデューサの入口流れの観察

Development of a high suction performance pump inducer is required for a reusable rocket engine to reduce total weight of a launch vehicle and to increase its reliability. But, flow patterns or pressure distributions in an inducer are not well known. Therefore, observations of flow patterns around an inducer by PIV (Particle Imaging Velocimetry) method were planned for the foundation data for a high suction performance inducer design. In this study, structures of the backflow and the reversed flow are minutely described and discussed.

ロケットエンジン用液水ターボポンプの開発

At present, National Space Development Agency of Japan (NASDA) is moving ahead of the development tests of the cryogenic engine LE-5, and setting further about the development of the second-generation, high-performance rocket engine LE-7.Combination of liquid oxygen (LOX) and liquid hydrogen (LH2) was chosen as propellants through the technological experiences of LE-5, to minimize the total vehicle weight for certain launching capacity into geostationary orbit.The most critical point to realize this high-performance engine is in the high pressure level, especially the turbopump discharge pressure must be increased remarkably.This paper concentrates on LE-7 LH2 turbopump and introduce followings.1) Required performance and Restraints for LH2 turbopump2) Description of design3) Technical problems

Design and analysis of small submersible pressure hulls

Small submersibles, which permit man to observe and work as part of the three-dimensional undersea environment, are among the most promising tools for achieving effective exploitation of the oceans. An important element of any submersible is the pressure hull, frequently contributing one-fourth to one-half and more of the total vehicle weight. The Naval Ship Research and Development Center has played a major role in developing pressure hull structures for undersea vehicles. This paper describes some of the principal structural features of existing and envisioned small submersibles and summarizes recent advances in design and analysis methods. Particular emphasis is given to computer programs developed and/or used at the Center. Specifically, it describes advances in stress, stability, and vibration analyses as well as early stage developments in structural fatigue and reliability analyses. It also discusses computer programs and automated procedures designed for rapid response in feasibility studies and preliminary and final design cycles; these provide for both the generation of input data and the graphical display of computed results.

A configuration for re-entry from mars missions using aerobraking

A new concept in re-entry vehicle configuration is proposed which results in a family of compact shapes with lift-to-drag (L/D) ratios of 0.5 to 1 .0. The main heat shield consists of a circular cone raked off at an angle to provide sufficient lifting surface. The afterbody is an elliptical cone fitted to the cross section of the forecone. Trim at zero angle of attack results in a symmetrical flow field over the forebody which makes the shape amenable to reliable analysis. Re-entry criteria are evaluated in terms of aerodynamic and guidance requirements for speeds up to 65,000 fps. These criteria are satisfied with an L/D value as low as 0.6 if a closed-loop re-entry guidance system is used. Operational trajectories are described, and sufficient corridor and range maneuverability is demonstrated using trimmed lift roll control. A detailed analysis of the radiative and convective heating shows that ablation heat-protection methods are adequate. Important factors affecting the heat transfer are radiation loss from the airstream, mass transpiration effects on the boundary layer, and shock-layer vorticity. For re-entry at 65,000 fps, the heat-shield weight for a six man vehicle is about one-third of the total vehicle weight.

Advanced Air-Breathing Engines

If we look at contemporary space vehicles which start their journeys from the surface of this planet, there is no doubt that the propulsion plant is the dominant feature. Physically it represents a major proportion of the total vehicle weight while the technical effort in attaining the necessary standards of performance and reliability has been of commensurate magnitude. It is clear also that the rocket motor has, at present, an unchallenged position as the chosen form of power unit. The question may well be asked in these circumstances what place there could be for an air-breathing power unit in such vehicles specifically intended to travel for most of their journey through the empty regions of space. Clearly the answer must be that such air-breathing units must function during the boost phase of space missions when there is air for them to breath so that the engines can add their quota of energy (kinetic plus potential) which is to be given to the vehicle in fulfilment of its task.

Factors Influencing the Size and Weight of Underwater Vehicles

Algebraic equations have been written to give direct expressions for the total weight and volume of an underwater vehicle of arbitrary speed and range in terms of performance requirements and component characteristics. The two equations are related through an average specific weight and a dead space coefficient. Equations for weight and volume influence coefficients of 15 design parameters are derived. O p t i m u m running speeds and ranges for stern-chase vehicles have been determined for: M i n i m u m propulsion system weight, m i n i m u m total weight of propulsion system and associated shell, and m i n i m u m propulsion system volume. For several cases studied, running speed ratios for m i n i m u m propulsion system weights are near 1.2. Sample calculations are given for two shaft driven vehicles, one with an electrical and one wi th a thermal propulsion system.