The Research Of Non-primary Detonator Based On DDT Theory

The detonator is the basic element of the primary explosive used in traditional detonator to make it explode. It is reliable, but the security is weak and has seriously environmental pollution during the production of the primary explosive. The deflagration to detonation transition (DDT) detonator based on the deflagration to detonation transition theory will be studied in this article. Steel constraint tube is used to realize the deflagration to detonation transition of intermediate charge. And the high explosive at the bottom will be detonated. The achievements of this paper as follows:1. Realizing DDT of intermediate charge is the key factor of detonating the high explosive at the bottom. DDT factors of steel constraint tube is studied in this paper. The results indicate that the best packing density of intermediate charge is 0.9～1.1 g/cm3. Steel constraint tube can realize the deflagration to detonation transition when the thickness of steel constraint tube is 0.9-1.0mm, and length of steel constraint tube is 30-35mm. The DDT process of PETN in the steel constraint tube:Intermediate charge fired by the the donor charge does the convective combustion. Shock wave formed by convective combustion gets into non reacting explosives, and non reacting explosives do low velocity detonation though rapid chemical reaction which is similar to thermal explosion mechanism. At last, high velocity detonation formed.Besides, the initiating ability of non-primary detonator is discussed in this paper. The result shows that the initiating ability of electric non-primary detonators and non-electric non-primary detonators are correspond GB8031-2005 and GB19417-2003.2. The flying process of explosion products and metal fragments of non-primary detonator is analyzed in this paper. The results show that explosion products fly directionally, and spread spherical based on the high explosive at the bottom.40μs after steel shell plain bottom non-primary detonator explosion, the radial diameter of the explosion products is 121mm. Expansion rate of explosion products is 1513 m/s in the radial direction.30 μs after steel shell concave bottom non-primary detonator explosion, the radial diameter of the explosion products is 107mm. Expansion rate of explosion products is 1783 m/s in the radial direction. The movement rate of explosion products of steel shell concave bottom detonators is higher than plain bottom detonators.3. Reversal bottom is changed by the fragment of the steel shell concave bottom detonator.due to the small plastic of steel material, metal jet can not be formed. There is velocity gradient within the reversal bottom. The speed of reversal bottom decreases first due to the tensile stress of the tail. And then the head reversal bottom separates from the tail at 95 μs, coming along with the increase of reversal bottom head speed as the tensile stress suddenly disappears. The velocity of fragments of steel shell, copper shell and aluminum shell non-primary detonator are compared. The result shows that the velocity of fragments of aluminum shell non-primary detonator is the best in the axial direction, and the velocity of fragments of steel shell non-primary detonator is the worst.