Regularity Study Of Projectile Nose Shape And Its Optimization Design

As the attacker in a war, hopes that the projectile will destroy enemies ’ armors orpositions to the utmost extent. So the projectile needs to have powerful penetrationability and anti-high overload capacity. And projectile nose shape plays a veryimportant role in this kind of problem. Actually, it is not at a nomal state whenprojectile penetrating the target. Affected by the self-gravity, the target resistance orair resistance the projectile always penentrates the target at a oblique angle. Thisdissertation makes a study on penetration capability and overload characteristics,mainly analyzes its regularity and makes an optimization design at last.Firstly, penentration regularity and ricochet are analyzed when the projectiles arewith blunt, hemispherical and conical nose shape. Under the circumstances ofdifferent angels and velocities, how the nose shape affected penentration performanceis studied. Then, some useful results are observed such as the way different projetilesdamaging the target, velocity curves versus time and kinetic energy loss curve versustime. What’s more, ricochet problem is studied by using the method of combiningresidual velocity and the midpoint displacement of projectile nose. At last, the rangesof ricochet critical angle are obtained with the same impact velocity. And thepenetration ability of the three projectiles are compared.Secondly, in order to get the optimal nose shape, optimal design are done on theproblem of rigid projectile with ogival nose shape penetrating limestone target. Usingthe stress which is based on cavity expansion theory and the effect of free surface hasbeen consided, the axial force and lateral force expressions of projectile are derivedwith the method of mathematical analysis. After minimize the stress function, theoptimal nose shape are obtained respectively. By comparison, the optimal nose shapedosen’t have the characteristic of taper, but is between ogival and conical shape.Finally, projectile nose shape are optimized by using the method of responsesurface. Two models are analyzed, one is hollow projectile penetrating concrete target.It only takes into account one factor about the curvature radius of nose, after samplepoints selection and numerical simulation, response values are extracted. Then theresponse surface models are established which met accuracy test. By callingMATLAB optimization function directly, the optimization models are calculated withdeceleration serving as the objective function. Finally, the projectile with optimal nose shape is reached which has the strongest ability of anti-high overload. The otheris ogival projectile penetrating multilayer media. Except for the curvature radius ofnose, it also takes into account oblique angle and attack angle. Besides, the attackangle is used as an uncertain factor, then make it become a uncertain optimizationproblem. The design of experiment is did by using latin hypercube sampling method.Also, deceleration serves as the objective function, and penetration depth functionserves as a constraint function. At last, the optimal nose shape is obtained by usinguncertain optimization method.