Behaviors of Initiation and after-Initiation for Homogeneous Explosives

Campbell's experimental studies of behaviors of initiation and after-initiation for homogeneous explosives were introduced and analyzed, but initiation conditions were not dealt with. Campbell's experimental results showed that detonation originated at the gap-explosive interface some microseconds of induction time later after the shock entered the nitromethane (NM). In other words, detonation is initiated by shock not instantaneously but directly (namely, not to pass through other processes, such as deflagration). The experimental data were newly treated, then they showed obviously that after initiation of detonation in NM the net detonation velocity is less than the normal detonation velocity. The experimental values of induction time decrease from 3.06 s to 0.705 s if the efficient pressures of shock wave increase from 8.82 GPa to 12.14 GPa. The two-phase repulsive-translation (A, m) equation of state was used to describe states of detonation product, and formularies of estimating induction time were derived newly and strictly from the thermal initiation theory. The calculated values of induction time estimated by the new formularies decrease from 248 s to 0.99 s if the efficient pressures of shock wave change in the same region. The calculated values of induction time are markedly higher than the experimental values. Thus this indicates that the thermal initiation theory is not applicable to describe the behaviors of shock initiation of NM. The cause is that the explanation of behaviors of shock initiation for homogeneous explosives with the thermal initiation theory does not accord with microscopic motion image of substance. Therefore, the thermal initiation theory is not the applicable one to describe behaviors of shock initiation for homogeneous explosives.