Analysis And Optimization Of Structural Parameters Of A Gun Affecting Projectile Initiation Disturbance

Initial disturbance of projectile is one of the chief factors influencing the fire accuracy of gun. This thesis took one lightweight towed howitzer as research object, and established a dynamical finite element model based on projectile-barrel coupling to describe the firing process. This thesis mainly studied the influence law of related parameters about the projectile motion in bore and initial disturbance of projectile, then the structural optimization design method to reduce the initial disturbance of projectile was studied. This paper can provide reference and technical approach for the structural optimization design of muzzle to improve the accuracy of the howitzer. Main contents in this paper are as follow:(1) This thesis discussed the nonlinear characteristics in dynamic analysis, and the dynamic analysis method of nonlinear finite element and their application was described. It laid theoretical foundation for establishing the fire dynamics model based on FEM. The finite element model of projectile-barrel coupling considering contact-impact between the projectile and the pipe’s rifling was established. And the fire dynamics model of towed and light howitzer based on FEM projectile-barrel coupling was established by the advantages of Abaqus/Implicit and Abaqus/Explicit solvers. Basing on these, we established the parametric modeling for the fire dynamics model based on FEM projectile-barrel coupling. They provided platform for the analysis and optimization of the initial disturbance of projectile.(2) The error sources affecting initial disturbance of projectile was analyzed. Then we analyzed the formation process and the influence to the gun firing dispersion extent of initial disturbance of projectile, the specific factors affecting initial disturbance of projectile was also analyzed. On the basis of the fire dynamics model based on FEM projectile-barrel coupling of one lightweight towed howitzer, the horizontal and vertical angular displacement, angular velocity and linear velocity were chosen as the characteristic parameters of the projectile motion, and these characteristic parameters out of muzzle were chosen to reflect initial disturbance of projectile. Then the influence of the structural parameters such as the interaction between projectile and gun, gun and different soils to both the projectile motion in bore and initial disturbance of projectile was analyzed in detail. It can provide reference for the design of structure parameters.(3) Some structure parameters were chosen combined the need of structure weight reduce with some condition of the range test for lightweight towed howitzer, the parametric modeling for the fire dynamics model based on FEM projectile-barrel coupling was established by use of them. By use of the horizontal and vertical angular displacement, angular velocity and linear velocity out of muzzle to reflect initial disturbance of projectile, the optimization objective function was established. The influence law and the degree of influence about structure parameters of howitzer on initial disturbance of projectile was obtained by means of sensitivity analysis of the OLHD. It can provide theoretical basis for the structural optimization design of muzzle to reduce the initial disturbance of projectile.(4) On the basis of sensitivity analysis about the structure parameters of howitzer. The author created the radial basis functions approximation models to replace the fire dynamics model based on FEM projectile-barrel coupling considering the computational cost of the model to optimize. The MIGA was employed in the optimization calculation about the structure parameters of gun to reduce the initial disturbance of projectile, the optimization purposes is reached. It can provide technical approach for structural optimization design of muzzle to improve the accuracy of the howitzer.