NUMERICAL AND EXPERIMENTAL MODAL ANALYSIS IN AN OFF-ROAD COMPETITION VEHICLE CHASSIS
Petterson Willians Rocha Abel1; Geice Paula Villibor1; Rodrigo Kotinda Tanigava1; Bruno César de Carvalho Tavares1; Joseph Kalil Khoury Junior1
1 Universidade Federal de Viçosa
doi:10.20906/CPS/COB-2015-0670
Resumo
The chassis of off-road vehicles, baja type, is subject to different sources of mechanical vibrations of which emphasis those from the irregular terrain, transferred by vehicle suspension system, and from the engine. If the excitation frequency is close to the structure natural frequencies can occur resonance phenomenon, generating vibrations and excessive deflections. The hypothesis that precedes the work is that when knowing the natural frequencies of chassis is possible to design a more comfortable and safe vehicle. Thus, the aim of the present work was realize an analytical and experimental modal analysis on the prototype chassis developed by UFVbaja team and comparison of the two methods used to find a possible solution modeling. The numerial analysis was performed using computer program ANSYS Multiphysics® through the Finite Element Method. It was determined the first five natural frequencies and their chassis vibration modes considering the boundary condition: free-free. Subsequently, the Baja chassis has been subjected to an experimental modal analysis on the same boundary conditions used in the computer simulations. The measurement system used in the experimental tests was composed of an impact hammer, uniaxial accelerometers, the acquisition module National Instruments® and Labview®. The points of excitement, by the impact hammer, and monitoring by the accelerometers were previously established based on the vibration intensity of the computational model, seeking no coincidence with the nodes of the studied vibration modes. Was also performed prior modal analysis of a simpler structure with the aim of understanding the implementation of the method. The numerical results obtained for simplified structure presented the first five natural frequencies equal to 36.49 Hz; 55.77 Hz; 60.84 Hz; 71.13 Hz and 77.23 Hz. Were analyzed 58 frequency spectra for six data points, with results for the natural frequencies equal to 36.33 Hz; 54.50 Hz; 57.81 Hz; 71.02 Hz and 77.23 Hz. When comparing with the frequencies obta
Palavras-chave: modal analysis ; Finite Element Method; natural frequencies ; free-free condition