Study On The Influence Of Density To The Performance Of Modified PTFE Kill Elements

The penetration-but-not-detonated of the ERA can be achieved by the use of PTFE shaped charge line in the forward charge of tandem warhead.But due to the weak dynamic mechanical properties of pure PTFE,the insufficient penetration ability problem of PTFE jet is caused.Under this premise,different mass fraction of Cu power is added for PTFE filling modification.Three different density of modified PTFE materials are designed and prepared in this paper.By the use of universal material testing machine and split Hopkinson pressure bar(SHPB),quasistatic and dynamic mechanical properties of modified PTFE were studied.The stress-strain relationships under different strain rate obtained.By using the finite element software AUTODYN-2D,the jet formation process of different density modified PTFE liner and the impacted process of shelled explosive are studied on numerical simulation.The influence of material density on the result of numerical simulation researched by comparative analysis,and obtained the initiation threshold u2 d value.The results show that:(1)Under the condition of quasi-static,with the increase of material density,the tensile strength and compressive strength of the modified PTFE increased,and the elongation at break decreased.The compressive strength of three kinds of modified PTFE materials(the density from low to high)was increased by 22.3%,27.1% and 33.8%,respectively,compared with that of pure PTFE.(2)Under the dynamic impact,the mechanical properties of PTFE materials showed obvious strain rate hardening phenomenon,compressive strength and critical strain rate increases obviously with the increase of strain rate;the material yield strength and compressive strength increased with the increasing of the density.(3)By using the static and dynamic compression experimental data,the Johnson-Cook constitutive equation of the different density modified PTFE material were selected and fitted at room temperature.(4)The modified PTFE liner jet formation simulation shell charge processed by AUTODYN-2D finite element software,the three kinds of modified PTFE materials jet the threshold charge with value were 25.04mm3/ S2,24.805 mm3/ S2 and 23.83 mm3/ S2,close to the value of 23 mm3/s2.which is given by Held;(5)Modified materials of the three density did not detonate shelled charge;for the configuration of 2/4/2 shell charge,at 3 times the standoff,with the increase of the density of material,the jet flow through the panel and the back hole diameter increases,with the increase of density of the modified materials;penetration depth that jet impacted on the main armor increases,the head speed of the jet formatted by PTFE-3 material is 3.2% lower than PTFE,the hole diameter is 25% lower,but the penetration depth is increased by 74%?...