Detonation thresholds

Detonation, Threshold Velocities Vc (Theoretical) far Impact Explosions of Massive Targets in. 

Bone et al attributed their positive results to the critical or detonation threshold nature of moist 2CO + C>2 mixts. Presumably the expected interactions of... 

Detonation, threshold velocities Vc (theoretical) for impact explns of massive targets in detonation 4 D623... 

A homogeneous model of this system which assumes that the mean temp rise of the mixt must be 350° in order for detonation to occur predicts the following detonation thresholds ... 

Liddiard (Ref 8a) ascribes this to longer duration and more planar shocks in the underwater expts. In any event, both sets of thresholds are considerably lower than those required to initiate detonation. A direct comparison (from Ref 8) of deflagration and detonation thresholds is shown in the tabulation below ... 

Impact to Detonation Threshold Velocity TATB d, Detonation Threshold Flyer Velocity, mm/y sec 42,46... 

They found a deflagration threshold pressure of 14kb as compared to 18kb for the detonation threshold. Bartels (Ref 50) investigated the shock behavior of coarse Tetryl at 1.65g/cc in a Plexiglass tube of 2lmm ID. He claims that no reaction occurs below 7.2kb and reaction is observed regularly above 12.1kb. With recrystd Tetryl of a finer particle size, the no-reaction level shifts to 9.1kb, while the reaction level is still 12.1kb... 

In these latter studies, strong shockwaves were produced by driving the free edge of the molecular solid with a steadily moving piston as depicted in the lower part of Fig. 3. Two-dimensional simulations were initially carried out to determine the piston driven shock-to-detonation threshold in the perfect crystal. Once this threshold was determined, a crack such as that depicted at the top of Fig. 19 was introduced. Additional simulations were then performed for a series of piston velocities near, but below, the critical piston velocity, Vp, that is necessary to cause detonation in defect-free... 

For strong shockwaves the presence of a single crack such as that depicted in Fig. 19 (top) was found to significantly reduce the shock-to-detonation threshold. This is demonstrated in Fig. 19 (bottom). This figure depicts the shockfront position versus time for a series of simulations... 

The results demonstrate that nanometer wide cracks can have severe effects on the shock-to-detonation threshold. It might be tempting to conclude that the chemical reactions caused by these defects result from a velocity doubling as atoms are spalled into the crack. Indeed, we found that the velocities of the leading particles that are spalled into the crack by the shockwave had approximately twice the particle flow velocity in the shockwave, as predicted by the continuum theory. However, we also observed that when these high velocity molecules struck the opposite side of the crack, reactions were not induced immediately. Rather, the complex motions of the many atoms within the crack appears to seed the chemical reactions that ultimately cause detonation. These studies lay the foundation for additional studies with more complex models. 

Monodimensional Model. P Shock wave H3C-N02 (C-K) the molecule correlated to detonation threshold P. 

Fig. 8 gives the variation of the detonation threshold as a function of the angle a of the N-C bond fixed in the crystal with the X axis of the shock wave propagation note that this angle will vary with the molecular crystal face attacked by the shock and will... 

Detonation threshold vs a angle between N-C bond and the X axis... 

If either a) or b) does not hold then the detonation threshold is not defined by a shock mechanism, and is not described by the theory given below. 

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