Informatics Publishing Limited

Shawki A. Abouel-Seoud ¹

Affiliations
1 Automotive Engg. Dept., Helwan University, Cairo, EG

Abstract

Ride comfort in road vehicles is related to vehicle vibration levels and the perception of passenger fatigue. In this study, vibration in vertical direction on the seat and floor are measured to characterise the ride comfort based on standard formulae and frequency analysis. A mid-size saloon vehicle and an off-road vehicle are driven on smooth, spalled and coarse asphalt road surfaces. To assess the vertical vibrations transmitted to the passengers, vibration dose values, Kurtosis, frequency response functions and power spectral densities of the compartment recorded signals were evaluated. Seat effective amplitude transmissibility value based on vibration RMS and vibration dose values were also evaluated. The results indicate that the vibration dose value increases in proportional to the vehicle speed and road roughness.

Keywords

Ride Comfort, Automotive Seat, Vibration Dose Values, Kurtosis, Power Spectral Density.

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Eid S. Mohamed ¹, Mohamed I. Khalil ¹, Shawki A. Abouel-Seoud ¹

Affiliations
1 Automotive Eng. Dept., Helwan University, Cairo, EG

Abstract

Modern integrated powertrains allow great scope for improvements in driveability, emissions and fuel consumption by optimizing the engine speed and load selection to deliver the demanded power. The aim of this study is to assess the exhaust emissions, road performance, road acceleration and fuel consumption of gasoline engine powered vehicle. The proposed emission index and fuel consumption rate are verified through chassis dynamometer tests using the urban part of European drive cycle (ECE-15). A midsize saloon vehicle equipped with an integrated gasoline engine with manual transmission (MT), automatic transmission (AT) and continuously variable transmission (CVT) powertrains. The results indicate that most of the carbon monoxide, carbon dioxide and unburned hydrocarbons emission, driveability and fuel consumption rate were improved for the CVT powertrains.

Keywords

Gasoline Engine, Continuously Variable Transmissions, Fuel Consumption, Driveability, Emissions.

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Shawki A. Abouel-Seoud ¹

Affiliations
1 Automotive Engg. Dept., Helwan University, Cairo, EG

Abstract

In this paper, assessment and evaluation of vehicle low frequency interior noise, infrasound closer to the threshold of hearing and their potential effects on human health are presented. The vehicle interior noise of off-road and mid-size vehicles was measured while driving on three different asphalt road surfaces. The results indicate that the vehicle acoustic comfort factor (VACF) should be at lower level for a relatively high acoustical comfort. Furthermore, at constant vehicle speed, the kurtosis parameter value is greater in high roughness road surface and is proportional to vehicle speed for every kind of road surface. Kurtosis has inverse effect on the VACF value. The VACF for road surface with higher roughness is lesser than the VACF for smoother road surface at same vehicle speeds.

Keywords

Low Frequency Sound, Vehicle Acoustic Comfort Factor, Noise and Vibration, Road Index, Vehicle Speed.

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Shawki A. Abouel-Seoud ¹

Affiliations
1 Automotive Engg. Dept., Helwan University, Cairo, EG

Abstract

Maintenance management for the gearbox systems aims at reducing the overall maintenance cost and improving the availability of the systems. Since the maintenance costs represent a substantial portion of the total life cycle costs, reliability and maintenance management of the gearbox systems have drawn increasing interests for the reduction of these costs. This paper considers a condition-based maintenance optimization for continuously degrading systems under continuous rotational vibration acceleration monitoring. After maintenance, the states of the system are randomly distributed with residual damage. An optimization technique is used to solve the preventive maintenance problem for faulty (cracked) gear tooth system. The situations where cracked gear tooth system has several ranges of performance levels are considered. To enhance cracked gear tooth system availability, possible preventive maintenance schedules are performed and affect strongly the effective age. Moreover, the technique is used to generate an optimal sequence of maintenance actions providing system working with the desired level of reliability during its lifetime with minimal maintenance cost rate. A single stage gearbox is used for this study, where multi-time tests were carried on healthy and faulty gearboxes individually. The measured and filtered rotational vibration acceleration was collected where hazard lifetime (LT) was determined at failure based on the Weibull distribution with assured reliability. The results indicate that the saving expected costs of either health or faulty gearbox, the basic maintenance cost (C), availability (AV) and maintenance basic cost and availability (CAV) savings have been estimated. On the other hand, the operating time between failure and optimum points for C, AV and CAV savings are all considered.

Keywords

Vibration Response, Gearbox, Preventive Maintenance, Weibull Distribution, Condition Monitoring, Hazard Rate.

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