Large Frame Commercial Ride Lawn Mowing Vehicle Dynamic Characteristics And Structural Optimization

This thesis takes the frame of riding lawn mowing vehicle as an object of study. The focus of the researches is on the finite element analysis of the frame dynamic characteristics and the discussion of the frame optimization in the light of practical requirements. The contents of the study include several aspects of the next.Do research on the geometry and physical properties of the lawn, the research determine the roughness power spectral density function of the lawn, and with the beginning of the function this study fit the surface curve of lawn in Matlab with the method of sine wave superposition. Do research on the wheel -grass contact model, the model can get the rolling resistance, stiffness and damping of the wheels by calculating. Create a frame model of riding lawn mowing vehicle in Pro/E, and divide the surface into finite element mesh with shell element when the model is taken into ANSYSWORKBENCH. Do research on the stress and deformation state in the condition of bending, braking, turning and reversing, and then make a program that improves the structure of the frame.Calculate the frame mode, and discuss possibility of the resonance state on the frame. Do research on the frame harmonic response with the incentive by cutting knives and ground and the dynamic response characteristics when the frame is at the different frequency. Establish the a simplified model of the riding lawn mowing vehicle, and then a finite element model of the whole vehicle including wheels and seat spring based on the simplified model. Wtih surface curve of lawn loading the on wheels, dynamic stress of the frame was calculated .Some compare reseach was done to the frame with different parameter in dynamic environment.At last,some topology optimization work was done to reduce the weight of the frame.