Study Of Ballistic Limit Of Dual-wall Bumper Shielding Structures

multi-wall shielding structures are an important measure to resist space debristhreaten great to spacecraft. The ballistic limit equation is the characterization ofshielding structure ability. The paper focuses on researching the ballistic limitequation of dual-wall plate shielding structures, using the method of theoreticalanalysis and the computer numerical simulation and the hypervelocity impactedexperiment.The paper will regard the dual-wall plate shielding structures as the whippleshielding structures with one shielding plate outside. Base on the damage situation,the projectile impacts the front two shielding plate, the paper will research fivesections，as ballistic range, second ballistic range, second shatter range, second meltrange and melt/vaporize range.In the ballistic range, after the projectile impacts the first shielding plate, a holeis generated in the first shielding plate and the projectile will keep its completenessand not change its mass. Firstly, base on conservation of energy and momentumconservation law, the remnant velocity of the projectile is established afterperforating the first plant and is checked by computer numerical simulation；Secondly, referring to whipple shielding structures ballistic limit equation in theballistic range, the ballistic limit equation of dual-wall plate shielding structureswith unknown parameter is established；Finally, through the hypervelocity impactexperiment, the ballistic limit curve of dual-wall plate shielding structures isestablished.In the second ballistic range, the debris cloud with solid particles is formedafter the projectile perforated the first plant. The debris cloud makes up of thebiggest mass and others mass fragments. The paper only considers the effects of thebiggest mass fragments against the whipple shielding structures. Firstly, the relationof the biggest fragments’ velocity and the projectile velocity is mastered；Secondly,referring to whipple shielding structures ballistic limit equation, the ballistic limitequations of dual-wall plate shielding structures with unknown parameters；Finally,through the hypervelocity impact experiments, the ballistic limit curve of dual-wallplate shielding structures are established.In second shatter range，base on the characteristics of the debris cloud，thepaper only considers the internal velocity of debris cloud effect on whipple shieldingstructure. Referring to whipple shielding structures ballistic limit equation, heballistic limit equation of dual-wall plate shielding structures with unknown parameter is established；Finally, through the hypervelocity impact experiment, theballistic limit curve of dual-wall plate shielding structures is established.In the second melt range, the debris cloud is separated as the front, the middleand the back debris cloud, with the biggest mass and velocity of the front debriscloud. Firstly, the paper considers the front debris cloud velocity as a whole againstthe whipple shielding structures; Secondly, base on the empirical equation of thefront debris cloud velocity, the front debris cloud velocity is obtained; Finally,referring to whipple shielding structures ballistic limit equation in the melt/vaporizerange, the ballistic limit equation of dual-wall plate shielding structures isestablished.In the melt/vaporize range, firstly, liquid or gas debris cloud is formed after theprojectile impacts the front two shielding plates; Secondly, the rear wall is subjectedto uniform load. Base on bending theory of plates and by Ritz method, theapproximate displacement of the rear plate subjected to partial uniform load. Finally,the ballistic limit equation of dual-wall shielding structures in the melt/vaporizerange is established through the dynamics analysis of the rear plate.Through the hypervelocity impact experiments, the paper studies the divisionof velocity ranges of whipple shielding structures and dual-wall shielding structures.The paper also compares the shielding ability between whipple shielding structuresand dual-wall shielding structures, in the same areal density, the shielding ability ofdual-wall plate shielding structures is better.In conclusion, the paper focuses on researching the ballistic limit equation ofdual-wall plate shielding structures and analyzes the differences between whippleshielding structures and dual-wall shielding structures. Research achievement canguide the development of multi-wall shielding structures ballistic limit equation andcontribute to the increase of spacecraft shielding performance.