Date of Award

2018

Document Type

Open Access Master's Report

Degree Name

Master of Science in Mechanical Engineering (MS)

Administrative Home Department

Department of Mechanical Engineering-Engineering Mechanics

Advisor 1

Mahdi Shahbakhti

Advisor 2

Darrell Robinette

Committee Member 1

Mo Rastgaar

Abstract

In modern-day automotive industry, automotive manufacturers pay keen attention to driver’s safety and comfort by ensuring good vehicle drivability, feel of acceleration, limiting jerk and noise. The vehicle driveline plays a critical role to meet these criteria. By using high-fidelity simulation tool such as AMESim®, it is now possible to accurately model the vehicle driveline to be tested for different scenarios. With Simulink®, one can develop an efficient torque-based control system to limit the driveline oscillations and the generated noise. So, a joint simulation is used which provides a platform to evaluate the estimators and control system while considering the fast dynamics of the non-linear system. This report presents the detailed driveline model developed to evaluate the important parameters which affect the driveline of a pickup truck. The model is developed considering the non-linear dynamics of the driveline, torque converter clutch dynamics and the non-linearities in the propeller shafts and the drive-shafts. It is then evaluated at different input conditions for two major test scenarios – tip-in and tip-out. Both scenarios show that the model displays the transmission and final drive backlash dynamics as anticipated in practical scenarios. The wheel speed shown by the results of the model proves that stiffness and damping coefficient of the tires play an important role in predicting the physical behavior of the vehicle. In addition, for the case of a tip-in from negative to positive torque, the effect of flexibilities of the driveshafts is shown as significant by this model. The oscillations caused due to these flexibilities are within 7 – 8 Hz range for evaluation at fifth gear. This frequency of oscillations found in this model is comparable to the results found in the literature. In future, experimental validation of the current full-order model would provide a better understanding of the assumptions considered while developing it. A reduced order model can be derived from the current model which can be further used to develop the estimators and controllers for active reduction of the driveline oscillations. Also, the overall effect of engine mounting system, comprehensive tire model and suspension dynamics on driveline oscillation can be studied.

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