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Title:	Parabolic leaf spring modeling for improved suspension system
Authors:	Kong Yat Sheng (P58198 )
Supervisor:	Mohd Zaidi Omar, Prof. Dr.
Keywords:	Suspension system
Issue Date:	2014
Description:	Dynamic behaviour of urban bus was investigated through numerical method in this research. Nowadays, demand for human sensation which is known as ride perception in the environment of a moving vehicle including bus has been increased. In order to improve the ride dynamics of the bus, the characteristic of suspension components which affect the dynamic response for common manoeuvres was investigated. To extract sufficiently reliable and accurate information related to its dynamics, a comprehensive bus ride dynamic simulation was developed. A finite element (FE) of bus full suspension configuration model which consists of actual body mass distribution, simplified axle and anti-roll bar, and also one dimensional beam element simplified parabolic leaf spring and shock absorber models has been modelled in FE environment. The leaf springs stiffness and shock absorbers damping properties were obtained through experiment method. FE Modal analysis was subsequently performed on the FE full suspension configured bus model to calculate the mode shapes and natural frequencies associated to the ride dynamics. Experimental time history data from on road testing was collected and Fourier transformed to correlate with the modal simulation results. After that, road surface excitation in displacement power spectral density form was used as input to the built bus model. Random vibration with the road power spectra input configuration has been assigned into the model with left and right track superposition as well as front and rear response time delay. After the setup has been completed, power spectral density acceleration output of bus body response was requested upon driver and different passenger region for comprehensive ride performance evaluation. Subsequently, performed suspension parameter sensitivity analysis was focused on parabolic leaf spring with another two vertical stiffness variants and shock absorbers damping characteristic to seek for different ride dynamics of the vehicle. The ride frequencies of the vehicle were associated to the ISO 2631-1 human comfort. The variation of ride index of the bus with suspension parameter modifications were observed and analysed. Besides the ride quality, the roll stiffness of the parabolic leaf spring variations were also obtained and correlated to vehicle body roll. Finally, implicit nonlinear FE scheme stress level validation of the parabolic leaf spring variants was performed to ensure the safety of the vehicle. In order to seek for good ride comfort, roll stability and safe design of vehicle suspension systems, parabolic leaf springs with different vertical stiffness and shock absorbers with different damping forces were analysed in FE full vehicle modal analysis along with roll stability analysis and stress level validation for failure prevention. As the final outcome, new designed parabolic leaf spring has successfully improved the ride of bus on driver side by 38% and passenger side by 29% when the bus is fully loaded. In terms of vehicle roll stability, the new designed suspension also increases the roll validation. The stress level is preserved within 1200 MPa which is the yield strength of the material. Therefore, it can be concluded that the new parabolic leaf spring designs have improved the vehicle ride and roll stability while maintaining the strength of the spring itself.,Master/Sarjana
Pages:	162
Call Number:	TA352.K644 2014 3 tesis
Publisher:	UKM, Bangi
Appears in Collections:	Faculty of Engineering and Built Environment / Fakulti Kejuruteraan dan Alam Bina

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