Preparation Of Functionally Graded Concrete And The Performance Of Anti-Tandem Warhead

The application of shaped charge structure in war has gone through the stages of shaped energy-piercing bombs,explosively formed projectiles and tandem-charge warhead.It is very important to master the damage mechanism of the tandem-charge warhead on concrete target and prepare the concrete target with great resistance of the tandem-charge warhead.In this paper,the performance of functionally graded concrete target against tandem warhead was studied by the combination of experiment and simulation.(1)The mix ratio of concrete and the structure of functionally graded concrete target were determined.The mix ratio was designed by Maximum Bulk Density Theory.The mechanical properties of concrete were best when the particle size distribution factor q was0.32.The functionally graded concrete with three-layer structure had best mechanical properties according to the experiments on graded sample with different layer structures and fiber fractions.The best proportion was selected under the constant total fiber volume ratio.The influences of each substructure on the overall properties of the material were analyzed.(2)The better fibers and aggregates for each functional area of functionally graded concrete target were selected.The concrete with 3% volume ratio steel fiber+1% volume ratio PVA fiber was selected as the crack resistance layer and the spalling resistance layer in functionally graded concrete target,and the concrete with 3% volume ratio steel fiber+ 20 mm ceramic balls or steel balls was selected as the anti-penetration layer,according to the experiments on samples with different combinations of fibers and aggregates.(3)The functionally graded concrete targets were subjected to shaped charge jet experiment,penetration experiment and explosion experiment successively.It was concluded that the penetration depth of the jet formed by the copper liner on the target was higher than that of the titanium alloy liner.However,the damage area of the jet formed by the titanium alloy liner on the target body were greater than that of the copper liner.The performance of steel balls targets on depths of destructions were better than ceramic balls targets,but the ceramic ball targets had greater performance on damage area and mass loss instead.(4)The finite element simulation of the process of the shaped charge jet penetrating the target was studied.The process of energy change in whole process of jet impact can be divide into stages of explosive initiation,jet forming and jet penetrating.The explosive energy utilization rate was calculated to be 42.7%.The energy conversion process,damage process,velocity change,acceleration change and equivalent stress change of the target subjected to jet impacts were discussed.