Global Journal of Researches in Engineering, A: Mechanical & Mechanics, Volume 22 Issue 1

Vibrational Behaviour of a Quarter Car Travelling over Road Humps with Different Suspension Systems © 2022 Global Journals Global Journal of Researches in Engineering (A ) Volume XxXII Issue I Version I 58 Year 2022 Fig. (14) shows the dynamic vibrational behaviour of a quarter car travelling over cat-eyehump at 40 km/h with the passive, the semi-active and the active suspension systems. As the vehicle speed is increased from 30 km/h to 40 km/h, the body vertical acceleration is reduced to about 5 m/s 2 referred to 30 km/h vehicle speed there is no change prompted in. However, the maximum value of the body vertical acceleration is about 7 m/s 2 as a passive suspension system is used while, this value is reduced to about 5 m/s 2 as active suspension system is applied. In the same context, the suspension working space is considerably reduced as the active suspension system is applied in comparison with passive suspension system. Differently, no change was prompted in dynamic tire load in both cases. Looking at the body displacement of the vehicle, there is a slight improvement when using active suspension system compared with passive suspension system. Figure15: Vibrational behaviour of vehicle over cat-eyehump at 50 km/h Fig. (15) shows the dynamic vibrational behaviour of a quarter car travelling over cat-eyehump at 50 km/h with passive. semi-active and active suspension systems. The body vertical acceleration are improved as the vehicle speed increased. There are no tangible changes prompted in the body vertical acceleration when the semi-active or the active suspension system are used. However, the maximum value of the body vertical acceleration is about 4m/s 2 as a passive suspension system is used while, this value is reduced to about 3.8 m/s 2 as active suspension system is applied. In the same context, the suspension working space is slightly reduced as the active suspension system is applied in comparison with passive suspension system. Differently, no change was prompted in dynamic tire load in both cases. Looking at the body displacement of the vehicle, there is a slight improvement when using active suspension system compared with passive suspension system. V. C onclusions The following conclusions can be achieved : • Mathematical models were introduced to study the vibrational behaviour of the vehicle when traveling over various types of road humps such as the circular, the trapezoidal and the cat-eye humps, using a passive, a semi-active and an active suspension systems . • The parameters that were investigated in this study to evaluate the ride comfort are the body vertical acceleration, the suspension working space, the dynamic tire load and the displacement of the body . • The ride comfort is greatly affected by driving over humps, especially at high speeds. • Traveling over humps, whether circular or trapezoidal, has a great impact on the comfort of riding, as well as the stability of the car . • There is a clear and tangible improvement when a semi-active suspension system is used compared to a passive suspension system. The semi-active suspension system is characterized by the presence of PID controller. The PID goal is to minimize the value of the body vertical acceleration values considering the body vertical acceleration as the controller input and changing the damping coefficient as the controller output . • These improvements were obtained in the body vertical acceleration, the suspension working space, the displacement of the body, and the dynamic tire load levels . • With the high speeds, the ride comfort is achieved for all the humps used in this study except for cat- eye hump, whereas the worth ride comfort is achieved at low speeds. • Therefore, through these results, it can be recommended to use the active or semi-active suspension systems instead of the passive