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991.
S. J. Kim S. G. Kim K. S. Oh S. K. Lee 《International Journal of Automotive Technology》2008,9(6):703-711
The excitation force of a powertrain is one of major sources of interior noise in a vehicle. This paper presents a novel approach
to predict the interior noise caused by the vibration of the powertrain by using the hybrid TPA (transfer path analysis) method.
Although the traditional transfer path analysis (TPA) is useful for the identification of powertrain noise sources, it is
difficult to modify the structure of a powertrain by using experiments for the reduction of vibration and noise. In order
to solve this problem, the vibration of the powertrain in a vehicle is numerically analyzed by using the finite element method
(FEM). The vibration of the other parts of the vehicle is investigated by using experiments based on vibrato-acoustic transfer
function (VATF) analysis. These two methods are combined for the prediction of interior noise caused by a powertrain. Throughout
this research, two papers are presented. This paper presents a simulation of the excitation force of the powertrain exciting
the vehicle body based on numerical simulation. The other paper presents a prediction of interior noise based on the hybrid
TPA, which uses the VATF of the car body and the excitation force predicted in this paper. 相似文献
992.
J. N. Kim H. Y. Kim S. S. Yoon S. D. Sa 《International Journal of Automotive Technology》2008,9(6):649-657
A fully three-dimensional model was used to investigate the optimal value for intake valve lift in a CAI engine. Uniform mixing
in the engine is a key parameter that affects the auto-ignition reliability and thermal efficiency. The method of intake of
the air supply often determines the uniformity (or quality) of the fuel-air mixture. In this paper, four strategies were applied
for controlling the swirl intensity of intake air. The variation of the intake valve lift induces different swirling and tumbling
intensities. Both experimental data and 1D WAVE software (Ricardo, Co.) were coupled with the 3D model to provide pressure and temperature boundary conditions. The initial condition of the
EGR mass fraction was also provided by the 1D model. The benchmark scenario (Case 1) was considered as a valve lift with 2
mm for all intake valves. We found that an intake valve lift of 6 mm with the other intake valve closed (i.e., Case 5) yielded
the largest swirling (helical motion in the axial direction) and tumbling, which in turn rendered optimal fuel-gas mixing.
We also found that fuel distribution affected the auto-ignition sites (or spot). The better the mixing, the greater the gas
temperature and combustion efficiency achieved, as seen in Case 5. The NOx level, however, was increased due to the gas temperature.
The optimal operating condition is selected from the viewpoints of environmental protection and combustion efficiency. 相似文献
993.
Fatigue design approach for the spot-welded T-type member using a simulated single spot-welded joint
In order to develop a fatigue design method for actual railroad car and commercial vehicle body structures using the fatigue
data of simulated single spot-welded lap joints, we first analyzed the stress distribution and evaluated fatigue strength
of spot-welded T-type members that are the components of actual railroad car and commercial vehicle body structures. Next,
fatigue design approach of these members using the fatigue data of single spot-welded lap joints was investigated. From our
results, we found that, even though there was a quantitative difference of fatigue strength between the single spot-welded
joint and the actual members over the same number of fatigue cycles, through the use of appropriate correction, the fatigue
design criterion of actual spot-welded members, such as those used in railroad car and commercial vehicle body, can be predicted
using the fatigue strength of single spot-welded joint. 相似文献
994.
A. Broatch J. M. Luján S. Ruiz P. Olmeda 《International Journal of Automotive Technology》2008,9(2):129-140
Most of hydrocarbon (HC) and carbon monoxide (CO) emissions from automotive DI Diesel engines are produced during the engine
warm-up period and are primarily caused by difficulties in obtaining stable and efficient combustion under these conditions.
Furthermore, the contribution of engine starting to these emissions is not negligible; since this operating condition is highly
unfavorable for the combustion progress. Additionally, the catalytic converter is ineffective due to the low engine temperature.
In conjunction with adequate engine settings (fuel injection and fresh air control), either the glow plugs or the intake air
heater are activated during a portion of the engine warm-up period, so that a nominal engine temperatures is reached faster,
and the impact of these difficulties is minimized. Measurement of gaseous pollutants during engine warm-up is currently possible
with detectors used in standard exhaust gas analyzers (EGA), which have response times well-suited for sampling at such transient
conditions. However, these devices are not suitable for the measurement of exhaust emissions produced during extremely short
time intervals, such as engine starting. Herein, we present a methodology for the measurement of the cumulative pollutant
emissions during the starting phase of passenger car DI Diesel engines, with the goal of overcoming this limitation by taking
advantage of standard detectors. In the proposed method, a warm canister is filled with an exhaust gas sample at constant
volumetric flow, during a time period that depends on the engine starting time; the gas concentration in the canister is later
evaluated with a standard EGA. When compared with direct pollutant measurements performed with a state-of-art EGA, the proposed
procedure was found to be more sensitive to combustion changes and provided more reliable data. 相似文献
995.
J. A. Calvo V. Díaz J. L. San Román D. García-Pozuelo 《International Journal of Automotive Technology》2008,9(4):467-472
In order to safely maintain a vehicle, it is necessary to verify the most important systems that affect safety during Periodic
Motor Vehicle Inspections (PMVIs). In a previous paper, a test method and validation criteria were suggested by the authors
to verify shock absorber status during PMVIs, as they are a fundamental component that may wear out during a vehicle’s life.
In this paper, variations of the performance of the vehicle’s brakes resulting from shock absorber wearing have been analyzed,
in order to confirm whether the suggested criteria is valid for taking into account longitudinal forces and pitch movement
on the vehicle. A simulation-based study was conducted with several configurations of a worn damper on a vehicle driving on
two virtual roads: smooth and undulating. The results confirmed that the damping coefficient established as an acceptable
value to verify the shock absorber status in PMVIs is also valid considering the forces involved in a braking maneuver. 相似文献
996.
997.
998.
The forward collision warning system, which warns danger to the driver after sensing possibility of crash in advance, has been actively studied recently. Such systems developed until now give a warning, regardless of driver’s driving propensity. However, it’s not reasonable to give a warning to every driver at the same time because drivers are different in driving propensity. In this study, to give a warning to each driver differently, three metrics classifying driver’s driving propensity were developed by using the driving data on a testing ground. These three metrics are the predicted time headway, required deceleration divided by the deceleration of the leading vehicle, and the resultant acceleration divided by the deceleration of the leading vehicle. Driving propensity was divided into 3 groups by using these metrics for braking and steering cases. In addition, these metrics were verified by making sure that braking propensity could be classified on public roads as well. 相似文献
999.
F. B. Romero J. M. McWilliams E. A. Fazio F. A. Izquierdo 《International Journal of Automotive Technology》2014,15(6):1027-1041
This paper has been developed in the framework of the alternative beam T-junction solution previously propoused by the authors (Alcalá et al., 2013), with the scope of optimizing the behavior of buses and coaches upper structures modeled with beam type elements. The alternative beam T-junction model proposed by the authors, had a total of six elastic elements at the junction level allowing to modify the localized rigidity of any modeled T-junctions, therefore improving their behavior and avoiding the well known rigidity issue these elements have. A fundamental aspect behind the use of these alternative beam models is related to the necessity of correctly estimating the rigidity values of the elastic elements for each modeled T-junction. In this context, we propose applying a surrogate model for the reference calculations which is based on statistical Bayesian kriging predictors. Statistical predictions have the added value, with respect to deterministic solutions, of providing a quantification of uncertainty. The development of the kriging predictors has required the application of a statistical methodology including computer experiment design, computation of moments of inertia, graphical and ANOVA type sensitivity analysis and Monte Carlo computation of Bayesian inference. The results of the application have been a very satisfactory trade-off between accuracy of approximation (prediction) and computational cost. The surrogate kriging models also provide an useful tool for a better understanding of the input-output relationships involved in the reference computations. 相似文献
1000.
J. Y. Kim D. H. Jung C. H. Jeong H. J. Choi 《International Journal of Automotive Technology》2014,15(6):961-966
The current test methods are insufficient to evaluate and ensure the safety and reliability of vehicle systems for all possible dynamic situations, including the worst case scenarios such as rollover, spin-out and so on. Although the known NHTSA Sine with Dwell steering maneuvers have been applied for the vehicle performance assessment, they are not enough to estimate other possible worst case scenarios. Therefore, it is crucial for us to verify the various worst case scenarios, including the existing severe steering maneuvers. This paper includes useful worst case scenarios based upon the existing worst case scenarios mentioned above and worst case evaluation for the vehicle dynamic controller in a simulation basis and UCC HILS. The only human steering angle was selected as a design parameter here and optimized to maximize the index function to be expressed in terms of both yaw rate and side slip angle. The obtained scenarios were enough to generate the worst case scenario to meet NHTSA worst case definition. It has been concluded that the new procedure in this paper is adequate to create other feasible worst case scenarios for a vehicle dynamic control system. 相似文献