Master of Science in Mechanical Engineering (MSME)
ABSTRACT The purpose of a suspension system for a vehicle is to contribute to the handling and assist in isolating the occupants from vibrations due to road irregularities. Generally, these primary functions are often at odds so the goal is to design a suspension system that finds the appropriate compromise. The focus of this thesis is to develop a two degree of freedom model and use parametric analysis to demonstrate an optimization technique by varying several geometric characteristics on a single-track vehicle. Furthermore, a dynamic vibration absorber will be added to the model to demonstrate its effect on the system. Also, out-of-plane motion will be discussed qualitatively. After modeling the system in the symmetric (vertical) plane, the equations of motion can be found using rigid body dynamics. The frame and suspension can be considered as a rigid body connected to the wheels with elastic systems. Basically, the rigid body constitutes the sprung mass while the masses attached to the wheels constitute the unsprung masses. Then the expression can be linearized and converted into a state space matrix where the eigenvalues, eigenvectors, and natural frequencies can be extracted. The parametric analysis consists of a perturbation of one parameter and measuring the effect on the natural frequency. The results show that the system is most sensitive to mass perturbations, especially at resonance. A dynamic vibration absorber is then attached to the system and subject to parametric analysis as well. The results show the system is most sensitive to variations in the forcing frequency on the primary mass. So a dynamic absorber would be more appropriate for a system subject to a single, fixed excitation frequency.
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Berner, Darrick Jason, "Parametric optimization of a single-tracked vehicle" (2013). LSU Master's Theses. 3549.