Mounted Mower Rollover Driver Damage And Improvement Of ROPS Collision Energy Absorption

From the perspective of improving driver safety,this paper combines finite element simulation and multi-rigid dynamics MADYMO software simulation to propose a Roll-Over Protective Structures?referred to as ROPS?during the rollover process.Increase the energy absorption structure for ROPS,and ultimately achieve the purpose of reducing driver damage.Firstly,the finite element simulation of the roll-over mower on the 15°ramp is carried out,and the impact load and centroid trajectory of the first collision with the slope are obtained.The tumbling test is carried out to verify the effectiveness of the finite element simulation model.The multi-rigid dynamics MADYMO model is used to simulate the driver's rollover process.The results show that both the ROPS and the ramp do not invade the Defination Limiting Volume?referred to as DLV?,and the driver uses the two-point seat belt during the entire rollover process.The neck was fatally injured.The driver using three-point seat belts is not fatally injured.Secondly,the impact energy generated by the collision of the mount mower under the rollover condition is converted into the internal energy of the ROPS.The more the impact energy absorbed by the ROPS,the less the driver's injury.Through the three-level four-factor orthogonal test,the maximum internal energy analysis of the ROPS under the side-turn of the riding mower is obtained.The combination of the maximum energy of the ROPS is 2mm and the slope of the slope is 36°.The ramp and tire friction coefficient is 0.7.By analyzing the maximum deformation of the ROPS,it is concluded that the smaller the slope the better the deformation of the ROPS.so that the deformation of the ROPS converts the energy inside the ROPS into other energy dissipation through deformation.It is most unfavorable for the energy conversion in the ROPS when the slope is at most 36°.When the slope is 36°,the impact energy can be converted into the maximum energy of the ROPS and the internal energy conversion of the ROPS is the least.Therefore,the slope of the mount lawn mower is studied with a slope gradient of 36°,a thickness of Q235 steel of 2 mm,and a slope and tire friction coefficient of 0.7.Finally,in order to improve the energy absorption characteristics of the ROPS,the axial and longitudinal energy absorption characteristics of the thin-walled tube structure were analyzed.The thin-walled tube of the four-cavity aluminum alloy Cell-4 was selected as the energy-absorbing structural component of the ROPS.The energy absorbing structure of the ROPS was designed.Under the dangerous conditions,the finite element simulation calculation of the rollover characteristics of the mount mower before and after the ROPS improvement was carried out.The simulation results show that the energy absorbed by the ROPS is 6.4 times before the improvement.The mount mower did not roll over.In the dangerous working condition,the MADYMO multi-rigid body simulation calculation was carried out on the rollover of the mount mower before and after the ROPS improvement.The simulation results show that the HIC₃₆ value of the driver's head evaluation index is reduced to 27.3%after the improvement of the ROPS.The 3ms acceleration of the indicator is reduced to 47.84%,that is,the ROPS increased energy absorption structure significantly reduces the driver's head damage.The bending moment of the neck is reduced to 32.64%,the axial pressure of the neck is reduced to 43.63%,and the axial tensile force of the neck is reduced to 89.81%,indicating that the ROPS energy-absorbing structure effectively reduces the damage of the driver'neck from axial and bending moments.