Study On Characteristics Of The Vehicle-mounted Weapon System Reload Buffer Airdrop Landing

The technology of soft landing is one of the most important technologies of heavy cargo airdrop system. As the cargo lands in a great velocity during the process of heavy cargo airdrop,it is necessary to take some cushion measures to ensure the safety and stability of soft landing, so the airbag cushion system is widely used. Against the backdrop of Defense Pre-research project, based on the finite element method, contact dynamics, elastic-plastic mechanics, rigid-body dynamics and optimal design theory, started with the airbag cushion technology, the research of key technologies for heavy cargo airdrop landing system are taken.The main research content is as follows:(1) As the airbag cushion technology plays the most important part of heavy cargo airdrop, the research of airbag cushion technology is taken first. Based on the uniform pressure equation, combined with control volume method and finite element method, the dynamic model of airbag cushion system is built, and the cushion property of airbag can be got by using the finite element software ls-dyna.(2) Because of the high load and great impact during soft landing process, it is necessary to take a strength analysis for the car frame and suspension of vehicle-mounted weapon system. The dynamic model of the vehicle-mounted weapon system with airbag, suspension and tire for heavy cargo airdrop during soft landing is established, as the motion of cargo is known, the suspension stroke can be calculated, then the strength of the suspension can be estimated. Based on the control volume method and finite element method,the model of the airdrop landing system with airbags, suspensions and crushable foam was built,then the cushion properties and the strength of frame could be got.(3)Taking the characteristic which results from the using of airbag into consideration, the height of barycenter of heavy cargo airdrop system will increases.therefore, it’s necessary to take a stability analysis of soft landing process. The process of soft landing divided into two parts, the process of airbag attenuation and the process of contact between the cargo and ground. In the first process, based on the energy conservation principle and thermodynamic equations, an analytical model of airbag attenuation system was established, then the attenuation properties could be got, and the cargo’s velocity and rotation angle before contact could be computed; in the second process, based on the theory of rigid-body dynamics and contact dynamics, an contact model between ground and the cargo with level initial velocity was built, the cargo’s velocity and rotation angle after impact could be got, then the stability of heavy cargo airdrop could be judged.(4) Considering that it is hard to get idea cushion property by experiment, a multi-objective optimization program is present for airbag. The height of airbag, the vent orifice area, the initial pressure and the bleeding pressure are treat as design variables, and the optimization objectives contents the acceleration and landing velocity of the cargo. Based on the multidisciplinary design optimization software mode-FRONTIER, adapting suitable DOE and optimization algorithm, combining the software Ls-Prepost and Ls-Dyna, the better cushion property can be got.