Study On Penetration Resistance Model Of Stone Concrete Target

Incorporation of stones with high strength when pouring large concrete fortifications can save cement and improve the overall structural strength.Meanwhile,the difference of strength between stone and concrete will easily generate uneven force on the projectile,causing ballistic deflection.Due to the random spatial distribution of shape and size of stones,resistance of the projectile while penetrating stone concrete target is different from that of homogeneous target such as plain concrete,and the magnitude and direction of the force will have obvious randomness.Considering that the use of stone concrete can increase strength of the structure,induce deflection of the projectile and achieve better anti-penetration performance,it has a high application value in the construction of military protection facilities.In view of the lack of relevant theoretical models and algorithms for penetration into stone concrete at present,the research on resistance model of stone concrete is carried out.In this paper,numerical simulation is conducted as a major tool to explore the influencing factors of the penetration resistance of stone concrete.Main results are as follows:(1)Through the comparison and analysis of several main methods to establish the numerical model of stone concrete,the three-dimensional Voronoi diagram method is selected,which can achieve a better simulation on shape of stone.There are also many ways to generate stones based on three-dimensional Voronoi diagram,including random extraction,scale scaling and generation of single stone,etc.The random extraction method with high efficiency and strong randomness is finally selected.(2)Currently mature theories,empirical formulas and engineering models of penetration resistance are mostly applicable to homogeneous targets which can’t be directly applied to solve the penetration problems of heterogeneous targets such as stone concrete.Based on the finite element simulation software,the factors affecting the anti-penetration performance of stone concrete are explored from the aspects of material strength,stone size,volume fraction of stone and structural thickness.It is found that the main influencing factors are strength of concrete and volume fraction of stone.In addition,the influence of size,strength of concrete and penetration velocity of the projectile on penetration resistance of stone concrete is explored.The results show that the stress on the surface elements of projectile can be analyzed and solved by using relevant theories.Simultaneously a modified surface element stress model is established.(3)The basic method to analyze stress of surface element is proposed and a visual penetration program is written.Based on this program,the penetration results of stone concrete under different incidence velocities,nutation angles and incident angles are discussed.In order to solve penetration problems of stone concrete as soon as possible,a random resistance model is established,feasibility of which is preliminarily verified compared with results of simulation.