Test Method And Experiment Study Of Critical Diameter

The critical diameter of explosives is one of the exact parameters describing the dynamics of detonation propagation,a set of critical diameter testing device was designed based on the Floret test for studying on the detonation propagation properties of small critical diameter charges.The short-duration pulse sensitivity test was carried out to select the primary charge.Some components of the test projectile have been optimized and then the factors of affecting the critical diameter were studied,and the critical diameter of several explosives were tested.The short-duration pulse sensitivity test was used to select the primary charge and its density.Considering the safety,energy output and short-duration pulse sensitivity,HMX fabricated by mechanical milling method was chosen and its charge density accounts for 90%of the theoretical maximum density(TMD).Suitable materials and sizes were selected for the accelerating barrel,witness plate,metal flyer and constraint cavity.The energy of direct acting on flyer and accelerating barrel was reduced by reducing the initial charge and adding a attenuation plate,then five materials with different hardness were selected to optimize the accelerating barrel.The results show that the most ideal material of accelerating barrel is T8 high carbon steel and its thickness is 1.8 mm.A simple analysis of the witness plate,flyer and constraint cavity was made,and it shows that the corresponding materials are T2 copper,304 stainless steel and 45~#steel respectively,and the thickness of the flyer is 0.15 mm.There are many factors that influence the critical diameter of explosives.The critical diameter of different conditions were measured by the detonation critical diameter test device.The influence rules of particle size,binder content,density and confinement strength on the critical diameter of explosives were investigated.The results show that the critical diameter of RDX based explosive decreases with the decrease of particle size,and increases with the increase of binder content.The critical diameter of JH-14 decreases with the increase of density.However,the critical diameter increases with the increase of density when the sample is TATB.Furthermore the critical diameter of the JH-14 decreases with the increase of the constraint strength.Four types of explosives were measured using the detonation critical diameter measuring device,the test shows that the critical diameters of FOX-7,NTO,JO-9C and PBXN-7 are 0.9mm,3.4 mm,0.6 mm and 1.75 mm respectively.