Study On Structural Parameters Of Large Caliber Guns Affecting Projectile Initiation Disturbance

The launch of artillery is a complex nonlinear dynamic problem. The theory of the finite element method is applied to the research of the large caliber gun, and the fire dynamics model based on FEM projectile-barrel coupling is established to simulate the process of projectile motion in consideration of the projectile engraving. The firing accuracy of the gun is measured by the initial disturbance of the projectile, and the influence of artillery structure parameters on initial disturbance of projectile is analyzed to provide the basis for the overall design and structural design of the artillery system. The main research contents of this thesis are as follows:(1) The basic theory of elastic-plasticity of the rotating band material is described in this thesis, and the basic theoretical formula of the elastic-plastic deformation of the material is introduced. It provides theoretical foundation for the rotating band material model. The rotating band material constitutive model is introduced, and the Johnson-Cook constitutive model is used to simulate the elastic and plastic properties of the rotating band material, and the cumulative damage caused by the rotating band is considered. At the same time projectile force analysis is established for the process of projectile engraving and the movement in the bore in respectively. The engraving force of the projectile is obtained, and the equations of the projectile motion in the bore are obtained.The results can provide theoretical basis for the process of projectile engraving and the movement in the bore.(2) Based on the finite element model of the whole gun dynamic finite element model, the influence of the material parameters of the projectile on the movement of the projectile in the bore is analyzed and compared by changing the material parameters of the rotating band, at the same time, the movement of projectile in the bore is analyzed and compared with the state of the friction property. Obtained by calculation, the influence of material parameters on the movement of projectile is very small, however, there is a difference between the motion of projectile in bore under different frictional properties.(3) The movement of projectile in bore is influenced by many factors, and the structure of the gun barrel is complex, so it has puzzled many researchers that how to establish the finite element model of the gun barrel. With the development of science and technology, the finite element model of the barrel of the gun barrel has been realized. The ALE mesh adaptive technology is used to divide the rotating band structure, considering the effect of pre bending on the gravity field. A dynamic finite element model of the whole gun considering the process of projectile engraving is constructed, and the band groove in the engraving process is simulated, and the movement law of the projectile in the process of projectile engraving and the movement in the bore is analyzed and compared. The process of projectile engraving has great influence on the movement of projectile in bore.(4) Based on the finite element model of projectile-barrel coupling system dynamics, the projectile angular displacement, angular velocity, velocity are chosen as the characteristic parameters of the projectile motion, and these characteristic parameters out of muzzle are chosen to reflect initial disturbance of projectile, and the optimization objective function of the initial disturbance of the projectile is constructed to measure the firing accuracy of the gun. The influence of artillery top carriage stiffness, cradle stiffness, barrel shape structure parameters of projectile initial disturbance is analyzed to provide the basis for the artillery structure design. An approximate model is constructed to match the stiffness of the top carriage and the cradle at the same time, and multi island genetic algorithm is used to calculate the approximate model.