Study On The Shock Initiation Technology Of Two Step Explosive Driven Flyer

Insensitive explosive is a kind of explosives of high security and is also the main charge of insensitive ammunition. Detonation energy threshold for insensitive explosives is much higher than that of ordinary explosives. The two step explosive driven flyer technology was studied to solve the reliable initiation of insensitive explosives. The topic in this paper provides initiation technology for insensitive munitions in small size and solves the basic application problems of energy transferring and matching of two step flyer. The research work is of great significance and value.In this paper, an two step flyer explosive train including the first Pb(N3)2 driven flyer and the second HNS-IV driven flyer was designed, its energy transferring and interface matching were studied by experiment and simulation, the results are as follows.(1) The performance of the Pb(N3)2 driven flyers were studied by experiments. The results shown flyer velocity depends on material, thickness and diameter. The stainless steel flyer can be accelerated to higher velocity than that of titanium flyer. The flyer velocity increases depending on thickness from 100μm to 150μm, but will decrease after 200μm at same diameter. The flyer velocity increases depending on diameter from 2mm to 3mm at same thickness. The results show that the optimal design conditions for the first explosive driven flyer is 150μm thickness,3 mm diameter and 3mm acceleration. The output pressure of Pb(N3)2 (03mm X 2mm) is 9.72Gpa and driven flyer can be accelerated to 1841m/s.(2) The Pb(N3)2 driving flyer process was simulated by nonlinear finite element analysis. It shows that the center part of the flyer is accelerated earlier than that of the other part. Aluminum flyer and stainless steel flyer can be cut and accelerated to higher velocity than titanium flyer, but the aluminum flyer is easily crushed to fragments during the flight. So stainless steel is the best among the three kinds of materials. The simulation results correspond to the experimental results.(3) The shock initiation process HNS-IV by flyer was simulated by nonlinear finite element analysis. It was found that the stress distributing in the central axis of the charge rises to a maximum value and then gradually decrease to a stable value. Stainless steel flyer is better than titanium flyer, and the critical initiating velocity of HNS-IV by stainless steel flyer is 980m/s. When HNS-IV is charged into steel house, the stress in the axis of charge will changes more quickly and reflected waves will be generate. The reflected wave peaks increase depending on the flyer thickness, but decrease depending on the diameter of flyer.(4) The driven flyer by HNS-IV charge ((?)4mm×4mm) was studied at different material and thickness. The results shown that The detonation pressure of HNS-IV was measured to be 17.85GPa. Under the same experimental condition, stainless steel flyer can be accelerated to higher velocity than that of titanium flyer. Steel flyer at 200μm thickness was driven by HNS-IV to 2452m/s at acceleration distance 3.2mm.