Research On The Optimization Design Of Negative Poisson's Ratio Structure For Occupant's Lower Limbs To Resist Explosion Impac

When the military vehicle is subjected to a bottom explosion,the occupants inside the vehicle will suffer unpredictable damage.The occupants’ lower limbs are extremely vulnerable under the bottom blast shock circumstance.To ensure the safety of the occupant’s lower limbs,the author of this paper proposes a double-arrow negative Poisson’s ratio lower limb protection device,the follow-up work is to optimize the design of the device through parameter analysis and the multi-objective optimization design methods,which effectively improved the protection performance of the device,and lowered the risk of injury to occupants’ lower limbs.Firstly,to simulate the effect of the bottom explosion of the military vehicle on the occupants’ lower limbs,a local equivalent model and corresponding equivalent acceleration conditions were extracted according to the existing researchs.The model’ accuracy was verified through finite element simulation(FEM),and the local equivalent model mentioned above can be used for further research,analysis and structural design.Secondly,the relative density of the double-arrow negative Poisson’s ratio structure is derived from the theoretical formula.Combined with quasi-static compression test and simulation,the mechanical properties,deformation mechanism and energy absorption characteristics of the double-arrow negative Poisson’s ratio honeycomb structure are analyzed.In order to investigate the protective effect of different structures on the occupants’ lower limbs,the double-arrow negative Poisson’s ratio structure,compared with hexagonal honeycomb structure with the same mass,were analyzed under the same bottom blast shock condition.The result shows that the double-arrow negative Poisson’s ratio structure presents better protection performance and energy absorption characteristics.Then a multi-scale parameter impact analysis is carried out on the device mentioned above,which is mainly manifested in the analysis of the occupant’s lower limb response and the energy absorption characteristics of the device.This paper discusses the protection principle of double-arrow negative Poisson’s ratio lower limb protection device under the explosive impact environment at the bottom of military vehicles,and the value range of the geometric parameters of the cell is determined.Finally,the multi-objective optimization design of the device is carried out,which effectively reduces the axial peak force of the occupants’ lower limbs and also meets the requirements of lightweight device.The researchs of this paper have certain guiding significance in reducing the risk of occupants’ lower limbs injury,and provide a new perspective for the protection of the occupants’ lower limbs in military vehicles.