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361.
Numerical Modelling for the Hydraulic Performance Prediction of Automotive Monotube Dampers 总被引:6,自引:0,他引:6
Kwangjin Lee 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1997,28(1):25-39
A computer model of an automotive monotube damper is developed based on fundamental principles of mechanics. The model can identify the required damper valve and/or size for the desired performance and hence speed the design process. Also, a parametric study can be easily conducted to understand the effects of parameters on the performance. A typical monotube damper is introduced and numerical formulations are described. Satisfactory agreement is achieved between model results and test data for a wide range of parameters including stroke conditions, valve combinations, and gas charge pressure. Some of these results are presented including the correlation at low and high speed strokes, cavitation simulation, and thermal effects on the performance. 相似文献
362.
Vehicle Dynamic Analysis and Evaluation of Continuously Controlled Semi-Active Suspensions Using Hardware-in-the-loop Simulation 总被引:3,自引:0,他引:3
Sung-Ho Hwang Seung-Jin Heo Hong-Seok Kim Kyo-Il Lee 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1997,27(5):423-434
A semi-active suspension system with continuously variable damper is greatly expected to be used mainly in the future as a high-performance suspension system due to its cost-effectiveness, light weight, and low energy consumption. In this paper, to develop a suitable control logic for the semi-active suspension system, the hardware-in-the-loop simulation is performed for the experimental continuously variable damper combined with a quarter-car model, and the simulation results are compared for passive, on/off controlled, and continuously controlled dampers in the aspects of ride comfort and driving safety, assuming each damper to be installed on the vehicle. 相似文献
363.
Study on sloshing in cargo tanks including hydroelastic effects 总被引:3,自引:0,他引:3
The sloshing problem in cargo tanks is studied through experiments and numerical analysis. The fluid motion is described
using a higher-order boundary element method and the structural response by a thin plate theory. It was found that hydraulic
jumps are formed when the excitation frequency is close to the resonance frequency in the case of low filling depth. In the
case of high filling depth, the flow resonates and hits the top of the tank, thus inducing a large impact pressure. The pressure
on the flexible plate shows amplified initial peaks followed by oscillatory components, the frequency of which coincides with
the natural frequencies of the plate in water as a result of hydroelastic effects.
Received for publication on Nov. 18, 1998; accepted on May 14, 1999 相似文献
364.
In the course of the last two decades Korean shipping has emerged as a major player in the liner market. In 1970 there was not a single container ship in the Korean fleet; yet, within the next two decades, shipping companies from Korea have become included among the top 10 liner operators in the world, in the context of a spectacular ascent of Asian companies in international container shipping. During the same period the organization of liner shipping itself underwent major changes. In the 1970s and 1980s, pools and powerful consortia prevailed, maximizing frequency and optimizing fleet deployment under pressure from the high investment entailed by containerization. The era of consortia, however, came to a close in the early 1990s; intermodalism and the expansion of the major liner companies into forward and backward segments of the transport chain rendered them inflexible for pursuing individual strategies of product diversification with a view to larger market shares. Global alliances were finally born as a result of a major reshuffling of co-operation agreements and of the globalization of the production process on the demand side. The aim of this paper is to follow and assess the options available to an aggressive low-cost national fleet in its journey to competitive maturity through a period of changing organization of liner shipping, focusing on the course of the leading Korean container company, and one of the largest in the world today, Hanjin. It highlights at the same time both the deep structural changes which liner shipping has undergone in the last two decades and the effects of current changes, such as the recent wave of mergers in this sector. 相似文献
365.
Some vehicle components are developed by setting target weights to the gram level at their design stages to accomplish a lightweight design. Recently, there have been many studies that have focused on lightweight design through the use of ultra-high-strength steels. However, a lightweight design can face many challenges if the reliability of the analysis is not also secured at the design stage. Such challenges include difficulties in coupled analyses when the file formats are different among PAM-STAMP, ABAQUS, and NASTRAN. In this study, we developed a mapping interface that enables mapping between the file formats of various software programs. Buckling analysis was coupled to the forming analysis, in which pre-strain test data were applied in considering the material’s strain hardening, to evaluate the rigidity of the front lower control arm that controls the wheels and transfers loads. The influence of forming effects on endurance was evaluated, and residual stresses around the weld zone were calculated. A comparison of experimental and analytical results indicated that the proposed analysis was highly reliable. 相似文献
366.
Kyuhyun Sim Sang-Min Oh Choul Namkoong Ji-Suk Lee Kwan-Soo Han Sung-Ho Hwang 《International Journal of Automotive Technology》2017,18(5):901-909
The plug-in hybrid electric vehicle (PHEV) has various driving modes used in both internal combustion engine and electric motors. The EV mode uses only an electric motor and the HEV mode uses both an engine and an electric motor. Specifically, when the PHEV of a pre-transmission parallel hybrid structure performs mode changing, its engine clutch is either engaged or disengaged, which is important in terms of ride comfort. In this paper, to enhance the mode changing process for the clutch engagement, a PHEV performance simulator is developed using MATLAB/Simulink based on system dynamics and experiment data. Vehicle driving analysis is carried out of the control logic and properties of the mode changing. A compensated torque is applied during the mode change. This results in the rapid speed synchronization with the clutch although the trade-off relationship of the mode change. In addition, the mode changing is conducted through the transmission shifting process to rapidly synchronize with speed. The control strategy implemented in this study is shown to improve the drivability and energy efficiency of a PHEV. 相似文献
367.
M. S. Wang N. T. Jeong K. S. Kim S. B. Choi S. M. Yang S. H. You J. H. Lee M. W. Suh 《International Journal of Automotive Technology》2016,17(1):165-173
Drowsy behavior is more likely to occur in sleep-deprived drivers. Individuals’ drowsy behavior detection technology should be developed to prevent drowsiness related crashes. Driving information such as acceleration, steering angle and velocity, and physiological signals of drivers such as electroencephalogram (EEG), and eye tracking are adopted in present drowsy behavior detection technologies. However, it is difficult to measure physiological signal, and eye tracking requires complex experiment equipment. As a result, driving information is adopted for drowsy driving detection. In order to achieve this purpose, driving experiment is performed for obtaining driving information through driving simulator. Moreover, this paper investigates effects of using different input parameter combinations, which is consisted of lateral acceleration, longitudinal acceleration, and steering angles with different time window sizes (i.e. 4 s, 10 s, 20 s, 30 s, 60 s), on drowsy driving detection using random forest algorithm. 20 s-size datasets using parameter combination of accelerations in lateral and longitudinal directions, compared to the other combination cases of driving information such as steering angles combined with lateral and longitudinal acceleration, steering angles only, longitudinal acceleration only, and lateral acceleration only, is considered the most effective information for drivers’ drowsy behavior detection. Moreover, comparing to ANN algorithm, RF algorithm performs better on processing complex input data for drowsy behavior detection. The results, which reveal high accuracy 84.8 % on drowsy driving behavior detection, can be applied on condition of operating real vehicles. 相似文献
368.
An accurate estimation of the maximum tire-road friction coefficient may provide higher performance in a vehicle active safety control system. Unfortunately, real-time tire-road friction coefficient estimation is costly and necessitates additional sensors that must be installed and maintained at all times. This paper proposes an advanced longitudinal tire-road friction coefficient estimation method that is capable of considering irregular road surfaces. The proposed algorithm uses a stiffness based estimation method, however, unlike previous studies, improvements were made by suggesting a third order model to solve problems related to nonlinear mu-slip curve. To attain the tire-road friction coefficient, real-time normalized force is obtained from the force estimator as exerted from the tire in the low slip region using the recursive least squares method. The decisive aspect of using the suggested algorithm lies in its low cost and versatility. It can be used under irregular road conditions due to its capability of easily obtaining wheel speed and acceleration values from production cars. The newly improved algorithm has been verified to computer simulations as well as compact size cars on dry asphalt conditions. 相似文献
369.
W.?Sung D.?S.?Hwang B.-J.?Jeong J.?Lee T.?KwonEmail author 《International Journal of Automotive Technology》2016,17(3):493-508
This paper reports the development of a battery model and its parameter estimator that are readily applicable to automotive battery management systems (BMSs). Due to the parameter estimator, the battery model can maintain reliability over the wider and longer use of the battery. To this end, the electrochemical model is used, which can reflect the aging-induced physicochemical changes in the battery to the aging-relevant parameters within the model. To update the effective kinetic and transport parameters using a computationally light BMS, the parameter estimator is built based on a covariance matrix adaptation evolution strategy (CMA-ES) that can function without the need for complex Jacobian matrix calculations. The existing CMA-ES implementation is modified primarily by region-based memory management such that it satisfies the memory constraints of the BMS. Among the several aging-relevant parameters, only the liquid-phase diffusivity of Li-ion is chosen to be estimated. This also facilitates integrating the parameter estimator into the BMS because a smaller number of parameter estimates yields the fewer number of iterations, thus, the greater computational efficiency of the parameter estimator. Consequently, the BMS-integrated parameter estimator enables the voltage to be predicted and the capacity retention to be estimated within 1 % error throughout the battery life-time. 相似文献
370.
S. J. Lee S. J. Jeong W. S. Kim C. B. Lee 《International Journal of Automotive Technology》2008,9(6):659-670
The use of a diesel particulate filter (DPF) in a diesel aftertreatment system has proven to be an effective and efficient
method for removing particulate matter (PM) in order to meet more stringent emission regulations without hurting engine performance.
One of the favorable PM regeneration technologies is the NO2-assisted regeneration method due to the capability of continuous regeneration of PM under a much lower temperature than that
of thermal regeneration. In the present study, the thermal behavior of the monolith during regeneration and the conversion
efficiency of NO2 from NO with an integrated exhaust system of a diesel oxidation catalyst (DOC) and DPF have been predicted by one-channel
numerical simulation. The simulation results of the DOC, DPF, and integrated DOC-DPF models are compared with experimental
data to verify the accuracy of the present model for the integrated DOC and DPF modeling. The effects of catalyst loading
inside the DOC and the volume ratio between the DOC and DPF on the pressure drop, the conversion efficiency, and the oxidation
rate of PM, have been numerically investigated. The results indicate that the case of the volume ratio of ‘DOC/DPF=1.5’ within
the same diameter of both monoliths produced close to the maximum conversion efficiency and oxidation rate of PM. Under the
engine operating condition of 175 kW at 2200 rpm, 100% load with a displacement of 8.1, approximately 55 g/ft3 of catalyst (Pt) loading inside the DOC with the active Pt surface of 5.3 m2/gpt was enough to maximize the conversion efficiency and oxidation rate of PM. 相似文献