Modal analysis and improvement of the frame for all

Frame is the bearing skeleton of the all-terrain vehicle, and its modal characteristics have a direct influence on the vibration and riding comfort of the entire vehicle. This article intends to investigate a certain domestic all-terrain vehicle whose frame is lengthened on the basis of benchmark vehicle, but this alteration leads to worse modal characteristics. Analytical method and experimental research are adopted for investigating the modal characteristics of this all-terrain vehicle frame. The response of the frame to different terrain roughness and various engine excitations is also discussed with the concluded results of modal analysis. It is found that these two factors are both likely to cause frame resonance. On the basis of the vibration pattern diagrams plotted, three improvement solutions are proposed, including adding transverse supporting beams, increasing the wall thickness of the longitudinal beam, and expanding the thickness of the rear vertical supporting beams. The modal characteristics of these three improvement schemes are also presented with analytical methods, confirming that the measures of adding transverse supporting beams and increasing the wall thickness of the longitudinal beam are feasible. Finally, the modal characteristics of the frame and the vibration of the entire vehicles are obviously improved