Design of a Microflyer Driven by a Microsized Charge Combined with an Initiation Criterion

In order to study the performance of ultra-fine 2,2', 4,4', 6,6'-hexanitrostilbene (HNS-IV) explosives initiated by a microflyer driven by microsized lead azide (Pb(N₃)₂), a corresponding simulation model was established in Autodyn software, and the accuracy of the simulation model was verified with a photonic Doppler velocimeter (PDV). Various influencing factors were studied in combination with the power flux-action time (Π-τ) initiation criterion. The results showed that the exponential growth rate of the flyer velocity decreased with an increase in the diameter and height of the lead azide and that the influence of the charge diameter was more obvious than that of the charge height. The flyer velocity increased linearly with the density of the lead azide. The velocity of the flyer also increased linearly with an increase in the shock wave impedance of the restraint materials, and the velocities of the flyer that corresponded to silicon and organic glass were lower than those of the metal materials. The flyer's velocity and power flux increased with a decrease in the flyer's density; when considering the flyer's velocity, power flux, and actual shear effect, titanium was the best material for the flyer. As the thickness of the flyer was decreased, the velocity and power flux of the flyer increased; under the premise of satisfying the forming effect, the thinner flyer was selected. When used as the material for the acceleration chamber, silicon showed a lower flyer velocity and power flux than sapphire, nickel, stainless steel, and other materials. With the increase in the acceleration chamber aperture, the exponentially declining trend in the flyer's velocity increased; when the aperture of the accelerating chamber was consistent with the diameter of the primary explosive, the power flux was the largest. Finally, the ability of the microflyer to initiate the HNS-IV was verified by a steel dent test.