Journal of agricultural engineering research vol:72 issue:3 pages:217-229
Chemical products for crop protection are usually distributed on the field as liquids by field sprayers. wanted horizontal and vertical sprayer boom movements create local under- and over-applications of spray liquid. A non-linear finite element model of a tractor and a mounted sprayer is developed to simulate these unwanted boom vibrations during field operations. Representative disturbance signals at the hitch point of the boom suspension are calculated for a tractor with a mounted sprayer driving over a standardized bumpy track. These disturbances are applied as input excitations to simulate boom movements for several types of suspensions (pendulum, single and double trapezium). Validation experiments with a simple 12 m boom on a hydraulic test rig indicate that this non-linear finite element modelling technique is a promising method for simulating boom movements of field sprayers. Further simulation results show that the modelled suspensions approximately halve the vertical motion of the boom compared with a rigidly mounted boom. Standard deviations of the vertical boom tip movements around the equilibrium position are, respectively, 0.44, 0.25 and 0.27 m for a fixed boom, a boom with pendulum suspension and a boom with trapezium suspension. This proves the effectiveness of existing vertical boom suspensions. (C) 1999 Silsoe Research Institute.