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REDUCTION OF STEERING VIBRATION WITH THE APPLICATION OF DYNAMIC TESTING AND ANALYSIS
ISSN: 0148-7191, e-ISSN: 2688-3627
To be published on November 21, 2019 by SAE International in United States
Event: NuGen Summit
KEYWORDS: Steering System, Engine Vibrations, Dynamics, Modal Testing, Modal Analysis, ABSTRACT - In modern agriculture, the tractor’s use is indispensable and essential for various operations like cultivation, soil preparation, pulverization and many more. However, despite being efficient machines, tractors may be subjected to different level of vibrations in various parts of their structure. The vibration often plays the key cause of invalidation and component failures and also, affecting the ride and comfort. Since it is known that such vibration factors can affect the behavior in many ways, an understanding of their dynamic response is warranted. In this paper, case study related to reduction of steering system vibration is presented. Objective and Background: Vibration reduction is linked with the reduction either at source or on path. For such, it is necessary to know the reality of machines, component and mechanisms to mitigate the vibration levels on the tractor. From the testing and analysis of the components, it is possible to calculate the dynamic properties and vibration average level. The vibration reduction decreases the damages caused by the friction between machines’ pieces and components, besides it decreases operator’s stress and consequently improve the ride and comfort quality. The engine is a major source of vibration. As three-cylinder engines are not well balanced, this results to more vibrations. The vibrations of the entire engine system as a block is usually integrated with the transmission case, supportive structures etc and therefore lead to the vibrations of other components. In the present work, the testing and analysis of tractor steering system is presented. In this, the root cause of vibration, identification of path of vibration and effect of engine vibrations (1 and 1.5 engine orders) are discussed. Then also, the way to reduce the vibrations are presented. Finally, design is chosen based on their dynamic response. Methodology: This paper focuses on the methodology to understand and predict the dynamic behavior of the system using various mechanical tests and simulations. The modal response of the model is acquired through experiments, and thus, determining its dynamic properties like modal frequencies. Next, the same model is analyzed by finite-element method, determining its dynamic properties. Thus, the results obtained through both the approaches are compared. Further, different designs are analyzed and tested towards vibration reduction. Results and Conclusion: The entire engine system is usually connected with the different structures and therefore, lead to the vibrations of other components. In case of steering system, it is found that vibration increases at specific RPM ranges. It is because of excitation of its natural frequency with engine 1.5 order excitation as input force. Modal frequencies are correlated from analysis and test. Most dominant path of excitation is identified. Different ways to reduce the vibration are discussed, either working on source or path. By introducing the rubber pad, vibrations are at normal level, but, at lesser torque which is NOT acceptable. Further, various testing and analysis are executed to understand the change of dynamics by varying the stiffness and mass of the system. Different solutions are proposed towards reduction of vibration.