Combined Gas Cannon Overload Test And Recovery Technology Research

In the development of precision electronics,smart ammunition and other technologies,impact and overload testing of related structures or materials are indispensable and very important.The combined gas gun can cover the range from low to high velocity impact and low overload to high overload tests with fewer components.In this paper,a combined gas gun which can be driven by powder or compressed gas and projectile receive system were designed.Firstly,the overall scheme of the system was designed with the background of laboratory application.The whole system adopts modular design,the powder launching part and the compressed gas launching part were designed separately and installed on the coaxial slide rail.They share the powder launching tube,buffer system and receive system.The compressed gas emission control adopts piston soft control.Aiming at the problem of gas emission control,the control process was analyzed by theoretical calculation method,which can provides a reference for the design of the structure.In order to obtain relevant parameters of the launch system,the launch dynamics process of the system was analyzed with Matlab/Simulink.Firstly,the compressed gas launching process was calculated based on the adiabatic expansion theory,and then the interior ballistic process was simulated based on the classical interior ballistic theory of single charge to obtain the relevant interior ballistic parameters,finally,the recoil motion of the system was analyzed.It was verified that the system has the capability of accelerating a 5kg projectile to the maximum 550m/s and the maximum overload exceeding 15000 g.To ensure the projectile is received safely by the receive system,the process of the projectile penetrating into soil was simulated using ANSYS/LS-DYNA explicit dynamic software based on Smooth Particle Hydrodynamics method(SPH).Firstly,the classical material model of soil was discussed,then the material models commonly used in ANSYS/LS-DYNA and their effectiveness of simulating projectile penetrating process were compared and analyzed,it was also compared with empirical formula and experimental results.Among them,the MAT?SOIL?AND?FOAM?FAILURE and MAT?PSEUDO?TENSOR model were good at describing soil deformation but poor at predicting penetration depth,and were not suitable for simulating soil under low confining pressure,while the MAT?FHWA?SOIL model was good at predicting penetration depth but poor at describing soil deformation.Aiming at the damage problem when the unstable projectile hits the receive tank,the trajectory of the projectile in soil was simulated and analyzed by numerical method firstly to obtain the possible location of the collision between the projectile and the receive tank.Then,based on the results,the process of the projectile hitting the receive tank plate was simulated with Finite Element Method to obtain variation law of the impact and the constraint reaction force.In the last,according to the above calculation and simulation results,the specific structure of the system was designed,and the strength of some key structures was checked.At the same time,a prototype was used to test the gas emission control structure and verified its effectiveness and reliability.