The Damage Charateristics And Ballistic Protection Perfomrnce Of Micro-porous Mullite By Hypervelocity Impacting

For the threat of millimeter-sized and smaller space debris' hypervelocity impact,the development of passive protection technology is an effective means to protect the safe operation of spacecraft in orbit.At present,the exploration of new protective materials' application is one of the research hotspots in space debris protection structures.In this paper,the hypervelocity impacting test method was used to study damage characteristics and ballistic protection performance of micro-porous mullite and protection structure based on micro-porous mullite.The research results can provide reference for the engineering design of spacecraft protection structure.First of all,for the micro-porous mullite thick plate,the hypervelocity impact experiments with different impact parameter were carried out.The damage characteristics and ballistic protection performance of micro-porous mullite thick plate by hypervelocity impacting of aluminum alloy projectiles.Combined with the damage characteristics of aluminum alloy spherical projectiles,the damage and protection mechanism of micro-porous mullite are preliminarily expounded.The micro-porous mullite cause the spindle-like cavity damage by the projectile hypervelocity impacting.Diameter of the cavity increases with the velocity of the projectile and depth of the cavity increases as the velocity of the projectile decreases.Depth of the cavity has limit values.In the course of hypervelocity impact,spherical aluminum alloy projectiles undergo plastic deformation and crushing with the velocity of the projectile decreasing,which helps to increase the protective ability of micro-porous mullite.Secondly,for the MPM-AL protection structure with micro-porous mullite as the front plate and aluminum alloy as the back plate,the hypervelocity impact experiments with different impact parameters,front plate thickness,and fixation methods of front and back plate were carried out.The damage morphology and characteristics of the structure were analyzed.Combined with the damage characteristics of the aluminum alloy ball projectile,the damage and protection mechanisms of the structure are preliminarily expounded.In the course of hypervelocity impact,spherical aluminum alloy projectiles undergo plastic deformation and fracture.The structural protection ability increases as the damage of the projectile increases.Degree of the projectile's damage increases with the velocity of the projectile and the thickness of the front plate..The non-adhesive fixing of the front and back plates contributes to the protection of the structure.Finally,for the stuffed Whipple shield structure that it consists of aluminum alloy bumper,micro-porous mullite intermediate bumper and aluminum alloy back plate,the hypervelocity impact experiments with different impact parameters,intermediate bumper thickness and layer distance(distance of intermediate bumper from the back plate)were carried out.The damage morphology and characteristics of the structure were analyzed.Combined with the damage characteristics of the aluminum alloy ball projectile,the damage and protection mechanisms of the structure are preliminarily expounded.By hypervelocity impacting,the bumper and intermediate bumper are perforated,and the back plate is pitted,bulged or perforated,and spherical aluminum alloy projectiles undergo plastic deformation,crushing,etc.As the velocity of the projectile and the thickness of the intermediate bumper increase,the damage of the projectile increases,and the structural protection ability increases.The non-adhesive fixing of the intermediate bumper and the back plate helps to increase the protection of the structure.There is an optimum layer distance so that the structure has the best protection performance.The protective performance of micro-porous mullite is comparable to Nextel/Kevlar.