Transmission of vibrations between towed and towing agricultural machines

In the research framework of acoustic and vibration problems, the vibrations produced by the agricultural machinery have a relevant position, because the vibrations due to the soil irregularity and to the operation of the machinery are transmitted to the seat of the tractor's operator, inducing comfort and safety problems, that are of interest of the National Institute for Insurance against Accidents at Work (INAIL). The objective of this work is to investigate the effect of machinery on the vibrations transmitted to the tractor's operator introducing a simplified model of an agricultural machine, considering not only the DoFs (degrees-of-freedom) relative to the tractor but also the ones relative to the machinery. Moreover, a model of the three point linkage between the tractor and the machinery and a model of the hitch for trailed machinery are proposed. The dynamic substructuring is exploited to couple the model of the tractor with the machinery through the linkage system and the transmissibility of an excitation force from the source to the operator's seat is investigated.