The study of stress in forage harvester is necessary, because the operation conditions are very different and rigorous. A calibrated datalogger system was used to measure the stress as function of time for a forage harvester. Mathematical models were developed to obtain the periodical variation of this stress by considering the influence of support wheel and the angular velocity of cutterheads. The agreement of these models was verified by the determination coefficient (R²). The periodical variation of stress as function of time for both experimental and theoretical values was graphically represented by using of the software EXCEL. It was observed that the minimal amplitude stress and the maximal periods of cycle corresponded to the treatments employed, which utilized the support wheel. The statistical analysis showed that the angular velocity of cutterheads presented significant difference, according to the Tukey Test for 5%. Based on the obtained results was concluded that, the stress cycle can be represented by senoidal functions with an adequate agreement, and that the operation time of harvesters can be increased by using a support wheel.
forage harvester; stress; mathematical models