Dynamic Analysis Of Thin-walled Projectile In Bore

With the development of powerful smart ammunition, constantly ask for an increase of the projectile intracavity volume to fill more explosive and all kinds of electronic components. In this case, the thin wall projectiles arose at the historic moment, but also triggered a series of problems in motion, contact and strength. These problems are to be solved at present.In this paper, theoretical modeling, numerical calculation and finite element simulation was used to study the motion, collision contact and dynamic strength of the shrapnel in bore. Based on the contrast of different wall thickness projectiles, summarized the interior ballistic dynamic characteristics of the thin wall ones.Considering the main loads that influence the projectile’s in-bore motion, according to the linear momentum theorem, angular momentum theorem and the constraint relations, translational motion differential equation, angular motion differential equation and collision motion algebraic equation of the projectile were derived respectively. By means of example calculation and local simulation, modified the determination method of the collision restitution coefficient, and set up the rebounded function relations of different wall thickness front bourrelets. According to the circulation order of the equations, used Runge-Kutta method to solve the mathematical model of the projectile’s in-bore motion by programming, output the time-history curves of the projectile axis’swing angle and swing angular velocity, and analyzed the influence of the main structure parameters’change on the motion parameters of the projectiles.A case study of a155mm shrapnel, based on the above analysis on the optimization of the projectile structure, theoretical formulas of the strength calculation were introduced to calculate the stress value of the risk points of different wall thickness ones. Under the same constraints and equivalent loads, applied the explicit dynamic simulation software to design the dynamic simulation tests of the projectiles, and the equivalent stress distribution of the projectile bodies and risk points’time-history curves were displayed. Finally, with the comparison of theoretical results and simulation results, the engineering practicability of the theoretical formulas were verified, and the influence law of the shell wall thickness reduction to the stress values and its distribution was summarized.