Criteria

Text:
Display:

Results

Viewing 1 to 30 of 4013
2009-04-20
Journal Article
2009-01-0004
Yoshihiro Okada, Takahide Nouzawa, Takaki Nakamura, Satoshi Okamoto
This study shows an example in which the conventional aerodynamic evaluation method that focuses on “steady” aerodynamic lift coefficient is not necessarily sufficient to evaluate vehicle's straight-ahead stability at high speed, and proposes a new aerodynamic evaluation method for vehicle stability. In vehicle development, it is generally said that vehicle with lower aerodynamic lift coefficient has better straight-ahead stability at high speed. However, in some cases, straight-ahead stability differs between two vehicles with similar low aerodynamic lift coefficient. It is natural to think that this variation is caused by the difference of suspension characteristics or vehicle body rigidity. But from our experiences, different straight-ahead stability was observed between two vehicles having same suspension characteristics, same vehicle body rigidity and almost similar aerodynamic lift coefficient, but different vehicle configurations.
2009-04-20
Technical Paper
2009-01-0003
Jeff Howell, Joshua Baden Fuller, Martin Passmore
Various studies have shown that the level of wind noise experienced inside cars on the road in unsteady conditions can be substantially different from that measured in wind tunnel tests conducted using a low turbulence facility. In this paper a simple geometric body representing the cabin of a passenger car has been used to investigate the effects of free stream turbulence, (FST), on the A-pillar vortex flowfield and the side glass pressure distribution. Beneath the A-pillar vortex, both mean and dynamic pressures are increased by FST. The unsteady pressure can be associated with wind noise and the flow visualization shows the peak unsteadiness is related to the separation of the secondary vortex.
2009-04-20
Journal Article
2009-01-0006
Takuji Nakashima, Makoto Tsubokura, Takahide Nouzawa, Takaki Nakamura, Masashi Ichimiya
In the present study, two kinds of simplified vehicle models, which can reproduce flow structures around the two sedan-type vehicles in the previous study, are constructed for the object and the unsteady flow structures are extracted using Large-Eddy Simulation technique. The numerical results are validated in a stationary condition by comparing the results with a wind-tunnel experiment and details of steady and unsteady flow characteristics around the models, especially above the trunk deck, are investigated. In quasi- and non- stationary manner with regard to vehicle pitch motion, unsteady flow characteristics are also investigated and their relations to an aerodynamic stability are discussed.
2009-04-20
Technical Paper
2009-01-0005
Günter Bischof
In a preceding paper an on-road investigation of the longitudinal aerodynamic response of a vehicle to ambient wind was presented. That study resulted in a frequency-dependent response function with a distinctive maximum within the range of the natural frequency of the vehicle on its suspension system. This finding raised the question as to whether the horizontal response of a car’s deceleration to wind gusts is associated with or caused by the suspension’s natural frequency. The objective of the present work is an attempt to shed some light on this question by the investigation of both deceleration and pitch angle fluctuations in additional on-road experiments. Both vehicle velocity and total airspeed in the driving direction and the pitch angle are recorded by independent data acquisition systems during a set of coastdown experiments.
2009-04-20
Journal Article
2009-01-0002
Scott Wordley, Jeff Saunders
This work presents a second series of turbulence measurements made in a range of different on-road terrains and traffic conditions. Wind measurements were captured using a rake of four separate multi-hole pressure probes mounted to the front of a test vehicle traveling at a road speed of 100 km/h. Analysis of the data shows how the turbulence intensities and length scales are modified by terrain type, road side obstacles and the upstream wakes of other moving vehicles. A vertical ‘profile’ of turbulence near the ground is generated and spatial correlations between probes are examined. These on-road results are then compared to the turbulence levels generated by the Monash University wind tunnel. A new method and a series of targets are then proposed for improving the modeling of turbulence in automotive wind tunnels.
2009-04-20
Journal Article
2009-01-0001
David Schröck, Nils Widdecke, Jochen Wiedemann
The unsteady environment road vehicles are exposed to is subject of many investigations that are currently made. Yet, the approaching flow is only one aspect of unsteady forces acting on the vehicle. Unsteady wake structures also lead to time-varying surface pressures and consequently fluctuating forces even in steady and low turbulent flows. However, little is known about the influence of realistic flow conditions, i.e. as found on road, on the unsteady surface pressures and wake structures of a vehicle. Therefore, to derive a deeper understanding of the unsteady aerodynamic properties of a vehicle this paper presents results of measurements conducted on a vehicle body both in smooth and turbulent flow conditions in the IVK model scale wind tunnel. Unsteady surface pressure measurements in the area where separation occurs and the base of the vehicle were made together with time accurate total pressure measurements in the wake.
2009-04-20
Journal Article
2009-01-0013
Jeff D. Colwell, Kaushik Biswas
One of the known causes of motor vehicle fires is hot surface ignition of combustible material that contacts engine exhaust system components. While ignition is a complicated phenomenon, the temperature of the surface is known to be an important parameter. However, little data is available in the literature concerning exhaust system temperatures, and much of this data is confounded by thermocouple attachment techniques and undocumented variations in driving conditions. In the present study, engine exhaust system temperature measurements were conducted using six test vehicles on a level, 2-mile oval test track at constant vehicle speeds ranging from 0 (idle) to 70 mph. By normalizing transient temperature curves with these steady-state temperatures along with ambient temperature, the rates at which the exhaust system components warm up and cool down are also compared.
2009-04-20
Journal Article
2009-01-0012
Christine S. Sloane
This paper is a review of the technical rationale for performance tests to qualify new hydrogen storage systems to assure safety throughout service life. SAE J2579 is used as an example of performance-based requirements. This paper is intended to broaden understanding of requirements for testing compressed gas storage that are under development at SAE and ISO.
2009-04-20
Technical Paper
2009-01-0014
Leland E. Shields, Daniele Staskal, Rose Ray, Linda Birnbaum, Robert R. Scheibe
The process of design inherently involves consideration of risk trade offs; intervening to reduce one risk often increases another. In addition to creating a design for the intended function of the product, a rational process of risk management involves prediction of risk through design analysis, statistical evaluation of the history of similar products, and potentially multidisciplinary teams to address diverse causes of risk. As a case study, this paper examines the benefits of using one class of fire retardant to reduce risk of vehicle fire injuries and the countervailing health risk due to increased quantities of fire retardants released in the interior environment. Data sources for fire and health risk were researched and interpreted for use in the analysis. Information needed to reduce the uncertainties in the risk predictions are identified for future refinements to the conclusions.
2009-04-20
Journal Article
2009-01-0008
Kennerly H. Digges
The basis for this analysis was NASS/CDS 1997 to 2006. In the NASS database there were 60 cases with major fires in side impact crashes, 37 of which were in passenger vehicles less than 10 years old. These newer vehicles were examined in this study. Cases in NASS were examined to identify crash characteristics associated with major fires in side crashes. The database contained 22 cases with fatalities, eleven of which were coded as fire related. Three of these were associated with fires that did not originate from the crashed vehicle. The fuel tank was coded as the fire origin for 41% of the major fires in vehicles with side damage and for 7 out of the 8 vehicles with fire related fatalities. The most frequent crash characteristic was an impact with a narrow object that produced severe side damage. Lower extent of damage was evident in two fatal cases that involved a rollover following the side impact.
2009-04-20
Journal Article
2009-01-0007
Makoto Tsubokura, Takuji Nakashima, Kozo Kitoh, Yoshihiro Sasaki, Nobuyuki Oshima, Toshio Kobayashi
A numerical method specially designed to predict unsteady aerodynamics of road vehicle was developed based on unstructured Large-Eddy Simulation (LES) technique. The code was intensively optimized for the Earth Simulator in Japan to deal with the excessive computational resources required for LES, and could treat numerical meshes of up to around 120 million elements. Moving boundary methods such as the Arbitrary Lagrangian-Eulerian (ALE) or the sliding method were implemented to handle dynamic motion of a vehicle body during aerodynamic assessment. The method can also model a gusty crosswind condition. The method was applied to three cases in which unsteady aerodynamics are expected to be crucial.
2009-04-20
Journal Article
2009-01-0011
Glenn W. Scheffler, Jake DeVaal, Gery J. Kissel, Michael Veenstra, Tommy Chang, Naoki Kinoshita, Matt McClory, Hajime Fukumoto, Marcel Halberstadt, Jesse Schneider
The SAE Fuel Cell Vehicle (FCV) Safety Working Group has been addressing FCV safety for over 9 years. The initial document, SAE J2578, was published in 2002. SAE J2578 has been valuable as a Recommended Practice for FCV development with regard to the identification of hazards and the definition of countermeasures to mitigate these hazards such that FCVs can be operated in the same manner as conventional gasoline internal combustion engine (ICE)-powered vehicles. SAE J2578 is currently being revised so that it will continue to be relevant as FCV development moves forward. For example, test methods were refined to verify the acceptability of hydrogen discharges when parking in residential garages and commercial structures and after crash tests prescribed by government regulation, and electrical requirements were updated to reflect the complexities of modern electrical circuits which interconnect both AC and DC circuits to improve efficiency and reduce cost.
2009-04-20
Technical Paper
2009-01-0009
Dieter Wolpert, Markus Egelhaaf
Further developments in automotive engineering and design contribute to vehicle safety. The increasing complexity of the systems complicates repair work. Faulty repairs can not only lead to malfunctions of the vehicle or components but also to vehicle fires. This paper presents some example cases of fire investigations directed at determining targeting to find out, whether the repair caused the fire or if other causes led to the ignition.
2009-04-20
Journal Article
2009-01-0021
Jessica Alessandro, Tetsuya Oda
Due to the progression of environmental regulations, as they pertain to interior air quality, automakers and their respective supply-chain are considering current and future volatile organic compound (VOC) requirements of the vehicle cabin. Currently, initiative is being taken in order to attempt to reduce the VOC levels associated with these and other products sold around the world. This paper will include an overview of existing regulations throughout the world and advancement in the reduction of VOC levels, including the methodology used to measure VOC content and specific technologies used to reduce VOC levels.
2009-04-20
Journal Article
2009-01-0023
Tsung-Yu Pan, Michael L. Santella, Nic Blundell
The Friction Stir Spot Welding (FSSW) process is a derivative of the friction stir welding (FSW) process, without lateral movement of the tool during the welding process. It has been applied in the production of aluminum joining for various Mazda and Toyota vehicles. Most of the applications and published studies were concentrated in aluminum sheet in the range of 1.0 to 1.5 mm, suitable for non-structural automotive closure applications. The objective of this study is to study the feasibility of FSSW process for automotive structural aluminum joining, up to 3 mm in thickness, for potentially replacement of self-piercing rivets (SPR) process. Joining thicker aluminum with FSSW tooling with a typical smooth concave shoulder and threaded probing pin, requires long process time, which would not be appropriate in mass-production automotive body construction. In this paper, an innovative FSSW tool with grooved shoulder was developed.
2009-04-20
Technical Paper
2009-01-0024
P. K. Mallick, Lavish Agarwal
Spot friction welding shows advantages over resistance spot welding for joining light alloys for automotive applications. In this research, fatigue behaviors of spot friction welded joints in lap shear specimens of AM-60 magnesium alloy and AA 5754 aluminum alloy were investigated. Static and fatigue tests were conducted with Mg-Mg, Al-Al and Al-Mg specimens. Fatigue S-N curves were obtained for all these specimens using load-controlled fatigue tests. Finite element analysis was conducted to investigate the stress distribution and the location of maximum stresses in spot friction welded joints in Mg-Mg specimens.
2009-04-20
Technical Paper
2009-01-0025
Francesco Vivio, Michele Ferracci
Riveting is a well established technology in the manufacturing of aeronautical structures as well as in the automotive industries. Despite its simplicity, the rivet presents a local stiffness that is not easy to properly model within a large finite element analysis. However, precision in the local stiffness evaluation is essential to perform any structural analysis when several rivet are applied in a joint structure. The result is that any rivet requires a local mesh refinement or, and this is the most common case, a drastic simplification of its structural modelling characteristics. In the present paper the structural behavior of a riveted lap joint connection was investigated experimentally and numerically using a new rivet finite element. The Rivet Element, based on a closed-form solution of a theoretical model of the rivet joint, is able to precisely evaluate, in FE analysis, both local and overall stiffness of riveted joints with a very low contribution of dofs.
2009-04-20
Journal Article
2009-01-0017
Vivek D. Bhise, Pankaj K. Mallick, Vishnuvardhan H. Sarma
This paper presents results of a three-phase research project aimed at understanding how future automotive interior materials should be selected or designed to satisfy the needs of the customers. The first project phase involved development of 22 five-point semantic differential scales to measure visual, visual-tactile, and evaluative characteristics of the materials. Some examples of the adjective pairs used to create the semantic differential scales to measure the perceptual characteristics of the material are: a) Visual: Light vs. Dark, Flat vs. Shiny, etc., b) Visual-Tactile: Smooth vs. Rough, Slippery vs. Sticky, Compressive vs. Non-Compressive, Textured vs. Non-Textured, etc., c) Evaluative (overall perception): Dislike vs. Like, Fake vs. Genuine, Cheap vs. Expensive, etc. In the second phase, 12 younger and 12 older drivers were asked to evaluate a number of different automotive interior materials by using the 22 semantic differential scales.
2009-04-20
Technical Paper
2009-01-0018
Duane M. Juriga
With the continued pressures on the automotive industry to improve quality and reduce costs by vehicle consumers, OEM (original equipment manufacturer) producers are continually looking to the supply base to provide lower cost solutions that do not sacrifice quality. One of the innovations which have been developed as a direct result of these industry pressures has been the evolution of a tufted PET (polyethylene terephthalate) carpet for automotive applications. New breakthroughs in the development of tufted PET carpet technology will allow suppliers to provide OEM’s with improved material performance characteristics, while at the same time, reducing costs. A significant benefit of this technology over conventional tufted products is the ability to utilize post consumer material content in the production of automotive grade main floor carpet and floor mats.
2009-04-20
Technical Paper
2009-01-0020
Naoko Yorozu, Chie Fukuhara, Takanobu Kamura
It is becoming common in recent years to take measures on vehicle interior noise by balancing other performances or by using acoustic materials that are advantageous in terms of weight and cost. However, acoustic materials for vehicles are mainly for reduction of high-frequency noise in the vehicle interior, and are not realistic measures for mid-frequency noise including road noise where reasonable thickness is needed. In this study, therefore, we identified the condition to reduce mid-frequency sound by focusing on the mechanism to reduce particle velocity as the sound absorption principle of acoustic materials and by utilizing acoustic materials in thin sheets used as a measure on high-frequency sound. We further derived the specific structure to realize this condition in order to reduce road noise.
2009-04-20
Journal Article
2009-01-0019
Terufumi Takayama, Kentaro Komabayasi, Masafumi Itou, Yuichi Miyake
Technological development of materials derived from plants (e.g., polylactic acid (PLA), and the like) is required to break dependence on fossil fuels and reduce CO2. PLA has inferior hydrolysis resistance, impact resistance, and molding ability than polypropylene (PP), and in order to overcome these disadvantages, a novel PP/PLA alloy has been conceived where PLA is incorporated into a PP matrix. By optimizing compatibilizer and elastomer addition, PLA has been successfully dispersed into a PP matrix at a sub-micron order, and interior parts have been successfully developed that fulfill the performance, appearance, and mass-production capability requirements for practical application.
2009-04-20
Technical Paper
2009-01-0031
M.P. Miles, K. Kohkonen, B. Weickum, Z. Feng
A new spot joining technology relying on a consumable joining bit has been developed and evaluated on dual phase (DP) 980 steel and a dissimilar combination of aluminum alloy 5754-O and DP 980. This new process, called friction bit joining (FBJ), uses a consumable bit to create a solid-state joint in sheet materials by the action of cutting and frictional bonding. A series of experiments were done in which different welding parameters were employed and lap shear tension testing was carried out to evaluate performance. The best lap shear values averaged 6.5 kN.
2009-04-20
Technical Paper
2009-01-0030
Wenkao Hou, Laurent Cretteur, Stephen Kelley
When a gap exists in a resistance spot welded (RSW) joint, the lack of intimate contact between the members at the faying interface can have a significant influence on sheet steel spot weldability, especially for advanced high strength steels. Several test joints simulating gap conditions observed in typical auto body structures have been designed for study of the effect of gap magnitude on the resistance spot weldability of such AHSS as DP980, DP780 and DP600. Tests show that an existing gap reduces the confinement of the molten zone during the welding process, increasing the probability of expulsion and therefore decreasing the current range. Increasing the electrode force helps reduce the gap influence and broadens the current range. Employing a longer weld time also has a beneficial effect when used in combination with an appropriate electrode force.
2009-04-20
Technical Paper
2009-01-0032
Y. J. Chao, Y. Kim, Zhili Feng, Srdjan Simunovic, Kathy Wang, Min Kuo
Static and dynamic strength tests were performed on spot welded specimens made of dual-phase (DP) 780 and mild steels (DQSK). Lap-shear (LS) and cross-tension (CT) as well as a new mixed mode specimen were studied using MTS hydraulic universal testing machine for static tests and drop weight tower for dynamic tests. Three weld nugget sizes were made for each steel and CT and LS. DP780 with one weld size was also tested in mixed mode. Load and displacement as functions of time and fracture mode of the spot welds were recorded. Representative data are reported in this paper.
2009-04-20
Technical Paper
2009-01-0033
S. T. Amancio-Filho, J. F. dos Santos
Polymer-metal hybrid structures frequently require joints due to limitations associated with component size, fabrication capabilities and physic-chemical material incompatibilities. The FricRiveting technique is a new alternative spot joining process developed to fill this gap. In the process a cylindrical metallic rivet is used to join one or more thermoplastic-metal components by means of plasticizing and deforming the tip of the rotating rivet through frictional heating (average temperatures within 300-500 °C). As an illustration of the process, sound joints on polyetherimide/aluminum 2024-T351 with elevated mechanical strength (up to 93% of the rivet strength) were successfully produced within short joining cycles and requiring minimal preparation of joining partners.
2009-04-20
Technical Paper
2009-01-0027
N. W. Wright, J. D. Robson, P. B. Prangnell
A single transducer wedge-reed ultrasonic welder has been used to make welds, in the non-age hardening aluminum alloy AA5754. A range of thickness combinations, varying from 1.2 mm to 2.5 mm, have been ultrasonically welded. A matrix of process parameters (input energy, impedance matching setting, tip clamp pressure and power) have been used to achieve high strength joints. Samples were welded in standard configuration for a tensile lap-shear test, which has been used to determine failure strength and type of failure. Optical microscopy has been used to reveal the bonding mechanisms. Variations in strength and failure mode have been related to changing process parameters and material thickness. It has been observed that stacking sequence has little effect on overall strength. Optimization of process parameters rather than the stack-up sequence has been shown to give the largest gains in joint strength.
2009-04-20
Journal Article
2009-01-0026
Francesco V ivio, Michele Ferracci
An analytical procedure for the evaluation of the elasticplastic behavior of spot welded joints is presented. The procedure is based on a new theoretical model of spot weld region: a circular plate having variable thickness with a central rigid nugget. The closed-form solution allows to describe the displacement of a rigid nugget when an axial orthogonal load is applied on the plate while plasticity and moderately large deflections are present. The goal is to reach a reliable spot weld region model which can be used as the basis to develop a spot weld element in FE analysis even when plasticity and large deflections are in effect. The analytical results obtained by using the new general relations precisely match those obtained modelling spot weld area by FEA.
2009-04-20
Journal Article
2009-01-0028
K. Sripichai, K. Asim, W. H. Jo, J. Pan, M. Li
Fatigue behavior of laser welds in lap-shear specimens of high strength low alloy (HSLA) steels is investigated based on a fatigue crack growth model. Fatigue experiments of laser welded lap-shear specimens were conducted. Analytical global stress intensity factor solutions are developed and compared with finite element computational results. A fatigue crack growth model based on the analytical local stress intensity factor solutions of kinked cracks and the Paris law for crack growth is then adopted to estimate the fatigue lives of the laser welds under cyclic loading conditions. The estimated fatigue lives are compared with the experimental results. The results indicate that the fatigue life predictions based on the fatigue crack growth model are slightly longer than the experimental results.
2009-04-20
Journal Article
2009-01-0029
P.-C. Lin, D.-A. Wang
In this paper, the stress intensity factor solutions for spot welds in U-shape specimens are investigated by finite element analyses. Three-dimensional finite element models are developed for U-shape specimens to obtain accurate stress intensity factor solutions. In contrast to the existing investigations of the stress intensity factor solutions based on the finite element analyses, various ratios of the sheet thickness to the nugget radius, the half width of the central square portions to the nugget radius and the half specimen length to the half specimen width are considered in this investigation. The computational results confirm the functional dependence on the nugget radius and sheet thickness of Zhang’s stress intensity factor solutions for U-shape specimens.
2009-04-20
Journal Article
2009-01-0046
Balarama Murty, Suresh Gopalakrishnan, Chandra Namuduri, Kenneth Shoemaker, Steve Opiteck, Bradley Bezzina
This paper describes a Magneto-Rheological coupling based Hydraulic Power Steering (MRHPS) system developed for improving fuel economy in conventional vehicles. The MRHPS system reduces the parasitic losses associated with the power steering pump and improves fuel economy in full-size trucks (and SUVs) by up to 3%, while maintaining the production hydraulic power steering system performance. The MRHPS is a low cost alternative to electric power steering and electro-hydraulic power steering systems and requires significantly less electric power while resulting in similar fuel economy gains. With the MR coupling the power steering pump is run at optimum speeds depending on the steering angle, angle rate and vehicle speed, and the pump is run in closed loop speed control mode so that factors like temperature, manufacturing tolerances, aging, etc. will not degrade the steering performance.
Viewing 1 to 30 of 4013

Filter

  • Range:
    to:
  • Year: