Dynamics Simulation For The Projectile-barrel Multi-body Launching System Of The Self-propelled Artillery

During the firing process of the self-propelled artillery, the large impact load is generated by the high-temperature high-pressure propellant gas in the bore, which may bring about the complex dynamic response of the system. Meanwhile, when the projectile moves at a high speed in the bore, there is a strong contact/impact between the projectile and the barrel due to the projectile-barrel gap, which results in the coupling between the elastic vibration of the barrel and the projectile motion. All the above cause the initial disturbance of the artillery and determine the state of the projectile out of the muzzle, which have a close bearing on the firing accuracy and firing stability of the artillery.Therefore, it is of important significance to establish the projectile-barrel multi-body dynamics model for the self-propelled artillery. The model should fully reflect the projectile-barrel interaction, and can obtain the influence of the structure parameters to both the system dynamic response characteristics and the projectile motion, and thus offer guidance for the artillery launch dynamics research and the structure optimization design. A certain type of medium caliber tracked self-propelled artillery is taken as the subject background in the thesis, and the main research contents and results are as follows:(1) In order to investigate the influence of the contact/impact between the projectile and the flexible barrel to the projectile motion and the muzzle vibration, a method was proposed by introducing the concept of virtual substance, in which the analog barrel composed by the virtual substances was used to transferred the projectile-barrel interaction force indirectly. Then a projectile-barrel rigid-flexible coupling multi-body model was built based on the virtual substances, and the corresponding dynamics equation was derived, which provides a theoretical foundation for the research of rigid-flexible coupling.(2) The relative coordinate theory and the recursive algorithm were introduced into the artillery system, and the recursive relationship between components was derived. At the same time, the flexible deformation of the barrel was described by the modal synthesis method, and the rigid-flexible coupling dynamics equations of the multi-body system were set up.(3) Based on the system dynamics theory described in the present paper, taking a medium caliber tracked self-propelled artillery as an example, the analog barrel composed by finite virtual substances was introduced into the projectile-barrel rigid-flexible coupling system. Considering the projectile-barrel contact/impact and the flexible deformation of the barrel, the multi-body dynamics model of the projectile-barrel system was established. The model is feasible by comparing the calculation results and the experimental data.(4) The discretization was carried out after regarding the interface between the projectile and the inner wall of the analog barrel as the regular geometric shape. When the barrel was considered as rigid and the projectile-barrel interaction was ignored, the variations of the muzzle vibration were also calculated for comparison. The results show that the projectile-barrel interaction must be taken into account in the artillery dynamics research. The motion law of the projectile in the analog barrel was obtained, and the equivalent transfer of the projectile-barrel interaction force was achieved, which can provide a new thought for the self-propelled artillery launch dynamics and the projectile-barrel coupling research.(5) Based on the launch dynamics model of the self-propelled artillery, considering the structure parameters of both the projectile-barrel interaction and the artillery itself, the horizontal and vertical angular velocity and linear velocity of the muzzle were taken as the characteristic parameters of the muzzle vibration, and the horizontal and vertical angular displacement, angular velocity and linear velocity were chosen as the characteristic parameters of the projectile motion, then the influences of the structure parameters to both the muzzle vibration and the projectile motion were analyzed in detail. The results show that the influence of the projectile-barrel structure parameters is more obvious than that of the artillery parameters, so the interaction force is not allowed to be ignored. Therefore, the impact of the projectile-barrel structure parameters must be fully taken into account in the artillery dynamics research. The results show that the influences of the structure parameters to the initial disturbances of the muzzle and the projectile are not entirely consistent.(6) Aim at the inconsistency of the initial disturbances of the muzzle and the projectile, a multi-objective optimization method was presented, in which the initial disturbances of the muzzle and the projectile were regarded as the optimization goal. Through the weighted normalization of several sub-goals, two sub-objective functions were obtained which can reflect the muzzle vibration and the initial disturbance of the projectile. On this basis, the multi-objective optimization model of the system was established, and the corresponding Pareto front was gained by NSGA II genetic algorithm, which can provide some references for the structural optimization research of the self-propelled artillery.