Shock duration

During the transient load phase of an accidental explosion, when the shock duration is less than the time of maximum response of the structural elements, member end rotations are limited to one degree. Maximum inelastic deformation is limited to three times the member elastic limit deflection. Since this loading phase is suddenly applied, use of material dynamic increase factors based on strain rate of loading are also used. 

Longueville et al (Ref 100) used flyer plates to study the shock sensitivity of RDX (and other expls) as a function of shock amplitude and shock duration. Their results for RDX are shown in Fig 6... 

The broken curves represent profiles of equal fluence, eg 10cal/cm2, etc. The solid curves are drawn thru the exptl data and separate the region of detons and failures. Note that the effect of shock duration for the finer RDX is rather mild and becomes somewhat more pronounced for the coarser RDX... 

The advantage of this flyer plate method is that shock duration r can be controlled by varying plate thickness, namely rs = 2h/Us, where h is plate thickness and Us is the shock velocity in the plate... 

We will postpone consideration of the effects of shock duration on shock sensitivity until we have described shock sensitivity tests (Section III) and take up this subject in Section IV... 

Thus far we have tacitly ignored the effect of shock duration on its capability of initiating detonation. For sustained shocks (> 1 microsecond duration) this appears permissible since initiation thresholds are only mildly influenced by shock duration of sustained shocks. We shall examine the effects of shock duration of siib-microsecond duration shocks in subsequent sections... 

These data show that particle size exerts a small but consistent effect on shock sensitivity D. Shock Duration... 

All containers are made of mild steel. The magnitude of the shock wave associated with the explosive detonation increases by convergence of shock wave due to the reduction of cross section area and reflection on the conical wall of the water tank. The pressure level and shock duration can be easily controlled by adjusting the mass and detonation velocity of explosive and the conical angle of the water container. 

Dalziel s Prediction Dalziel felt that the three major factors of concern for ventricular fibrillation are body weight, current magnitude, and shock duration. He used the results of animal studies, conducted by Ferris (1936) and Kouwenhoven (1959), to establish an equation for the minimum threshold of fibrillation. Dalziel developed the following equation for predicting the minimum threshold value of fibrillation for a body weight of 50 kg (110 lb) ... 

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