The Composition,Structure And Performance Under The Combined Loadings Of Penetration And Explosion Of Functionally-graded Cement-based Composites

Fortifications suffer more combined loadings of penetration and explosion with the development of armor piercing shell and earth penetrating weapon.As the main components of fortifications,ordinary concrete can no longer meet the actual need.In this paper,the following contents are researched to improve the performance under the combined loadings of penetration and explosion.(1)Target structure.By studying the effects of structure on the functionally-graded cement-based composites,a three-layer structure was chose.(2)Raw materials selection and mix proportion design of functional layers.Considering the performance requirements of anti-explosion and anti-penetration,the targets were divided into distinct functional layers,and each layer was optimized.Thus,the crack resistance layer was prepared by 6mm and 20 mm flat steel fibers at a total volume of 6% with 3:3 hybrid,and the anti-penetration layer was prepared by five types of aggregates such as alumina ceramic balls and brown corundum.(3)Performance under the combined loadings of penetration and explosion.According to the above results,BS,BT and BZ targets,BX targets and NC targets were prepared,and subjected to tests under penetration and blast.For BX targets,the proportion of damaged area was 27.33% and 62.87% respectively,which was at a lower level in all targets.And for BS,BT and BZ targets,the presence of aggregates kept the damage depth within 100 mm,much lower than the damage depth of NC and BX targets.Therefore,performance under the combined loadings of penetration and explosion of the targets is: functional gradient target with high-strength hard aggregate(BS,BT and BZ targets)> ultra-high performance fiber concrete target(BX targets)> ordinary concrete target(NC targets).(4)Depth formula under the combined loadings of penetration and explosion.Based on actual data,several formulas for penetration depth and explosion depth were investigated,and also improved by introducing the coarse aggregates parameters and the unification theory.On this basis,the damage depth formula under the combined loadings of penetration and explosion was proposed.The error between calculation and actuality was controlled at 1%,3% and 10% respectively.