Research On The Protection Mechanism Of Vehicle Bottom Protection Component

It is one of the important measures for military vehicles to resist the explosive threat of mines and improvised explosive devices on the battlefield by installing anti-explosion protection components at the bottom of vehicles,aiming to reduce the explosive impact of vehicles and occupants and improve their survivability on the battlefield.At present,V-shaped structure and sandwich-shaped structure are commonly used as explosion protection structures under vehicles.Researchers have done a lot of design,simulation and experiment on different types of anti-explosion protection components,but there are few studies on the protection mechanism of anti-explosion protection components,and lack of systematic theoretical guidance for corresponding design.In addition,the explosion simulation and experiment around the vehicle has problems of high cost and poor repeatability.Therefore,this paper develops a scale model by using the similarity law and Hopkinson-Cranz proportionality Law.The calculation cost can be greatly reduced by using the scale model to study the protection mechanism of V-shaped structure and sandwich-shaped structure.The conclusions can be used to predict the response of the anti-explosion protection components at the bottom of the vehicle under the action of explosion load and guide the corresponding optimization design.In this paper,the propagation characteristics of blast wave are studied and the formula of impulse is obtained.The similarity law is deduced by dimensional analysis method and hopkinson-Cranz proportionality law is combined to provide theoretical support for subsequent model scaling and explosion simulation research.Then,the accuracy of the established scale model was verified by the pendulum experiment,and the response of plate,V-shaped plate and laminated plate to the changes of various parameters under the local explosion load was studied,including the influences of plate Angle,thickness,explosive equivalent,blast distance,eccentricity and material arrangement order.When the design space at the bottom of the vehicle is large,the V-shaped car bottom structure with simpler structure can be used.When the design space at the bottom of the vehicle is small,the flat bottom structure can only be used to ensure that there is enough energy absorption effect.Therefore,this paper studies the protection mechanism of V-shaped and sandwich-shaped protection components respectively.Due to the complex structure of the bottom of the vehicle,the transmission paths of the loads from the protection components to the upper structure is uncertain.Therefore,the design and research of the anti-explosion protection components should be carried out on the vehicle,and the interaction between the protection components and each component should be fully considered in combination with the layout of the vehicle chassis.The accuracy of the established vehicle finite element model is verified by the calibration simulation and experimental results.On this basis,according to the conclusions of the scale model research,the anti-explosion protection components at the bottom of a certain vehicle is designed considering the requirements of protection performance and lightweight.Firstly,three kinds of single plate structures were designed: double V structure,triple V structure and trapezoidal structure.The protection effect of the three structures under 6kg TNT explosion was compared,and the analysis of load transfer path determined that the double V structure could provide the best protection effect.Then a sandwich-shaped protection component is designed on the basis of trapezoidal structure,and its protective performance and mechanism are studied.Finally,considering the requirements of anti-explosion protection performance and lightweight,multi-objective optimization was carried out for the designed double V-shaped protection component and the sandwich-shaped protection component.Kriging method was used to fit the approximate model,and non-dominated sorting genetic algorithm(NSGA-II)was used to obtain the Pareto solution set of the optimization target,and the optimal design of the two protection components was obtained.