Use of simulation techniques to improve tractor operator safety

Most of the serious accidents in agriculture occur in the area of tractor roll-over. In order to reduce the number of work accidents, manufacturers have mandatory to equip their tractors with ROPS and seat safety belt anchorages, according to the European Community directive 2003/37/EC. In this field of very high interest for worker safety, we have been carrying out a research activity aimed to analyse the injuries to operators and the effectiveness of restraint systems, by using a multibody-FEA approach. In particular the Madymo code is utilised (MAthematical DYnamic MOdels, TNO Automotive Safety Solutions). In a previous paper we analysed the roll-over dynamics of a wheeled tractor with narrow track, placed on a slope, by means of a pure multibody scenario. Both the tractor structure and the ground were indeed modelled as infinitely rigid. In this paper the behaviour of two typical type of soil have been implemented in the model (by means of a FE description), analysed and compared with that of the rigid one. The aim of the study is to analyze how the soil mechanical strength affects the results of the accident dynamics simulation, by comparing the values both of the kinematic parameters and of the operator biological traumas. A better, more realistic description of all the interesting quantities is obtained, as expected.