Study On Hypervelocity Impact Characteristics Of Porous Materials

The increasingly frequent space activities of human beings have produced more and more space debris,and the existence of these debris is a serious threat to the operational safety of spacecraft.Porous materials have the advantages of light weight,high structural specific stiffness,good thermal insulation performance,etc.,and are used more and more widely in spacecraft structures(such as thermal insulation structures).The impact damage and protection of porous materials is becoming more and more important for the safe operation of spacecraft in orbit.To solve this problem,this paper studies the hypervelocity impact characteristics of space debris of porous materials.A cubic cell geometry model of porous materials was established for the distribution and shape of porous materials.The geometric model of the porous material is established by the arrangement and combination of the unit cell models.Combined with the state equation,the strength model,the failure model and the SPH algorithm,the hypervelocity impact analysis model for porous materials was established.Through the different arrangement and combination of the unit cell model,the effects of different pore arrangement methods on the hypervelocity impact characteristics of porous materials were studied.In order to verify the correctness of the hypervelocity impact analysis model of the porous material,a typical porous material,AL-foam,was selected for the hypervelocity impact experiment.The correctness and effectiveness of the established porous material model were verified by comparing the diameters of the perforated areas of AL-foam in experiments and simulations.In addition,this paper also carried out an hypervelocity impact test of flexible polyurethane foam.The experimental results show that the flexible polyurethane foam acts as a filler between the protective screens of the aramid fiber woven fabric,which can effectively block the impact of the projectile debris cloud,thus effectively reducing the damage of the debris cloud to the fiber woven fabric.For the established hypervelocity impact analysis model of pseudo-random porous materials,the influence of pore size on its hypervelocity impact characteristics is analyzed.The results show that with the same porosity,with the increase of pore size,the difference between the kinetic energy absorption rate of the elastic material and the homogenous material at the same areal density increases first and then decreases.In addition,the influence of material parameters,projectile diameter and projectile velocity on its hypervelocity impact characteristics was studied by using the hypervelocity analysis model of porous materials.The simulation results show that the density has a great influence on the kinetic energy of the absorbed material of the porous material,and the shear modulus and strength have little effect on the kinetic energy of the absorbed projectile.When the diameter of the projectile is constant,as the velocity of the projectile increases,the absorption rate of the kinetic energy of the projectile by the porous material decreases.When the velocity of the projectile is constant,as the diameter of the projectile increases,the absorption rate of the kinetic energy of the projectile by the porous material decreases.