Research On Airdrop Buffer Of Storage And Transportation Box Considering Propellant Damag

During the airdrop landing of the launch canister,the ground will have a huge impact on the launch canister,which makes it difficult to accurately evaluate the system safety,especially the ammunition safety problem.The damage of solid propellant has an important impact on the launch safety of rocket weapons.This topic focuses on the propellant damage during air drop landing,and designs the corresponding buffer scheme to avoid the damage.The main research contents include:(1)The damage assessment analysis of solid propellant grain under impact load is carried out.Firstly,based on the theory of fracture mechanics and the structural integrity evaluation method of rocket engine,the fracture mechanics criterion is proposed as the failure criterion of propellant in airdrop process,and the extended finite element method is proposed as the calculation method of propellant damage analysis.The feasibility of the method is verified by the comparison of tensile simulation and experimental results.Secondly,according to the shape structure of solid propellant grain,established the damage containing finite element model,calculated the cracks of modified double base propellant and HTPB propellant under impact load,and studied the changes of damage dissipation energy under initial damage at different angles.The results show that HTPB propellant has better impact resistance than modified double base propellant,The calculation results lay a foundation for the buffer scheme design of air drop system.(2)The simulation calculation of airdrop without buffer and the calculation of propellant crack propagation are carried out.Firstly,the overall scheme design of launch canister airdrop is completed through the selection of cargo platform and the layout of launch canister.Secondly,in order to obtain the dangerous position and rocket overload under the impact of the airdrop of the launch box,the finite element simulation model of the airdrop system is established.Considering the uncertain factors such as cross wind and ground during the airdrop landing,the horizontal and inclined landing are simulated,and the force of the launch canister and rocket overload curves under various working conditions are obtained.Finally,taking the rocket overload curve as the input,the propellant crack propagation is calculated,and the propellant damage under different landing conditions is obtained.The proposed crack calculation method is applied to practical engineering problems.(3)The buffer scheme design of launch box and the air drop simulation with buffer are carried out.Firstly,the applicable conditions of the commonly used buffer methods are analyzed.Combined with the characteristics of reloading airdrop and the basic assumptions of landing process,the airbag buffer suitable for airdrop of launch canister is determined,and the analytical model of the buffer method is established.Secondly,the airbag parameters are designed according to the airbag design process.Based on the airbag finite element algorithm,a simple airdrop model is established to verify and optimize the parameters,and finally determine the parameters such as airbag height,exhaust hole area and airbag spacing.Finally,the finite element model of the launch box airdrop system is established to simulate and analyze the normal and bad landing conditions.The results show that the airbag buffer scheme has obvious effect,greatly reduces the stress level of the launch box and rocket overload,and effectively ensures the equipment safety.