CENTROID SWINGING PROPERTY OF A MACHINE BODY UNDERGOING LONGITUDINAL EXCITATION IN A STRAW COMPRESSION BALER

ABSTRACT During the harvesting of waste straw in the field, a self-propelled baler undergoes significant oscillations in the longitudinal direction around its centre of gravity, which greatly affect the stability of operation and the comfort of the driver. In order to analyse the vibration characteristics of the main frame under multi-source excitation, the complete frame is divided into a chassis frame and a baling frame. A nine-degree-of-freedom vibration system model of the whole machine is established based on the relationship between the internal motion devices, and simulations are carried out using MATLAB/Simulink. In addition, a multi-body dynamics simulation of the compression device is carried out, and the law governing the variation in force at different unit points of the mechanism is analysed. Finally, the vibration response of the main frame under different working conditions is explored. The results show that the main frequency component of the frame in the no-load state is 80 Hz, and the main response frequency of the frame is about 1.6 Hz, a finding that is consistent with the operating frequency of the compression mechanism. In particular, the displacement amplitude of the simulated signal at the centroid position is consistent with that measured in experiments, which verifies the validity of the dynamic model. Our results can provide guidance for future work aiming to further reduce the body vibration amplitude and optimise the design of the frame.