Assessing safety conformance of ROPS system in B10 tractors

The driver's safety in the event of a vehicle rollover is a very important issue. Therefore, a mandatory certification requirement of any vehicle is to assess the safety of the protective structures of ROPS cabs. The safety of tractor cabs is assessed by full-scale experiments. Due to modern computer technologies, we managed to assess the safety of a tractor cab based on a numerical experiment. The paper presents a mathematical model for assessing the safety of protective ROPS structures of an industrial tractor B10. A tractor rollover is simulated with a series of static loads (lateral, vertical, and longitudinal). Plastic deformation of the protective structure makes it possible to minimize the expected crash-impact energy. A mathematical model of simulation tests was developed using the finite element method. To take into account the plastic state of the structure, the static problem was stated and solved by methods of nonlinear analysis taking into account the effect of large displacements. The calculation results showed that the expected crash-impact energy of 40,867 J for a 25-ton B10 tractor was achieved at a displacement of 261 mm and a lateral force of 229 kN. The structure remained functional under its subsequent loading with a vertical force of 500 kN and a longitudinal force of 170 kN. Its performance criterion was intact limited space of the driver's supposed location. A full-scale experiment confirmed the adequacy of the mathematical model and the safety of the protective structure. The experimental crash-impact energy was achieved at a displacement of 261 mm with a lateral force of 243 kN. The value of the experimental force differed from that of the calculated force by less than 4%. The rate of energy gain was tested additionally. To this end, we plotted the force against the structure deformation. The deformation energy was calculated as the area under this curve. The value of the experimental energy differed from that of the calculated energy by less than 7.3% over the entire range of studied structural deformations.