Research On Penetration Mechanism And Related Issues Of The Tube-rod Extended Penetrator

New and efficient penetrator structure is an important development trend of kinetic energy projectile. As a new special-shaped penetrator, the tube-rod extended penetrator can effectively avoid series of problems brought by the large fineness ratio of the rod projectile, and can bring armor-piercing power gain. It has broad applied prospects in piercing field. According to the extended penetrator in this paper, by using theoretical analysis with numerical simulation and experimental research, a systematic research was conducted on normal and oblique penetration into the homogeneous armor steel target, its head structure of the related penetration issues, and the situation of penetration gain. This research can offer technical support and theoretic foundation for penetration damage assessment and system design of new kinetic energy weapon.The main contents could be summarized as follows:(1) Mechanism and characteristics study on the tube-rod extended penetrator’s normal penetration into target.Based on A-T model of rod type penetrator’s, with comprehensive consideration of the structural features of extended penetrator and adiabatic shear mechanism in the penetration process. The simplified theoretical model of tube-rod extended penetrator’s normal penetration of the semi-infinite homogeneous target was established. Within the velocity of 1300m/s～1800m/s, the change situation of residual velocity and residual length of penetrator with penetration depth have been acquired based on the calculation of theoretical model in the different penetration stage. Simultaneously, some corresponding researches of numerical simulation and have been carried out, the theoretical calculation is consistent with the latter two. The simulation and experiment results demonstrated that the peculiar physical phenomena of extended penetrator and its formation mechanism, and the related factors generating the penetration advantages in the penetration process.(2) Mechanism and characteristics study on the tube-rod extended penetrator’s oblique penetration into target.Based on the stress analysis of different stages of penetration, and combined with the mass center motion equation, the swing equation around the mass center, the analytical model of the tube-rod extended penetrator’s oblique penetration of the finite homogeneous target was established. Calculation of theoretical model and numerical simulations were conducted with impact angles of 45° and 60° to the target thickness of 60mm. The limit penetration velocity, the change law of residual velocity varies according to impact velocity and other penetration characteristics were obtained by calculating. And experimental verification was conducted to the impact-angle of 45°. In the respects of the penetration depth of the tube assembly and the rod, the residual mass after penetrating the target plate, the theoretical model, the numerical simulation and the experiment results were in good agreement. Based on the above-mentioned theoretical model of oblique penetration to finite target, the analytical model of the tube-rod extended penetrator’s oblique penetration of the semi-infinite target was established. Analytical model calculations and numerical simulations were conducted on oblique penetration of the semi-infinite target with impact-angle of 45° and 60° in two conditions. The variations of penetration depth with impact velocity and penetration path characteristics were obtained. Furthermore, the impact of the attack angle to the oblique penetration was explored in this chapter.(3) Related issues study on nose structures penetrating different types of target.To further enhance the structural advantages of extended penetrator, related issues to nose structures penetrating different types of target were studied. Based on semi-empirical model, the oval nose among the four typical rigid nose structures had the highest efficiency in normal penetration. The numerical simulation results for five kinds of nose structures oblique penetration into finite target showed that the truncated conical nose was the most advantageous one. The study was also done in the field of four types of nose structures oblique penetration three-layer laminated target. The aluminum ogive and piercing block was found most efficient, and its advantages in the nose structure penetration mechanism were analyzed. The ricochet of the truncated conical nose to thin metal target was studied. Based on Tate ricochet model, the correction ricochet model considering target thickness model was established.(4) Study on penetration gain of tube-rod extended penetrator.Through the description and analysis of the penetration gain mechanism of extended structure, based on tube-to-rod penetration depth discount coefficient and rod penetration depth empirical formula, the penetration depth gain analytical model of the extended penetrator normal penetration of the semi-infinite target is derived. By model calculation and numerical simulation, the penetration depth gain variation of the penetrator to baseline rod normal penetration into the semi-infinite target were obtained along with velocity. The study of extended penetrator oblique penetration into finite target was conducted at three kinds of impact angle by numerical simulation. The penetration depth gain was obtained and analyzed. Furthermore, the change situation of residual kinetic energy gain was carried out along with time for normal penetration into the semi-infinite thickness target and oblique penetration into finite thickness target.