Peak Static Overpressure (Ps)
Definition
The maximum pressure increase above ambient at the shock front, the primary structural damage parameter, scaling with the inverse cube root of range (Hopkinson-Cranz law).
- Symbol
- Ps
- Definition
- Maximum pressure increase above ambient at the shock front
- Significance
- Primary structural damage parameter
- Scaling law
- Inverse cube root of range, Hopkinson-Cranz law
Common questions
Why does peak overpressure fall off with the cube root of distance rather than distance itself?+
Blast energy from a given charge spreads through an expanding spherical volume, so the Hopkinson-Cranz scaling relationship links overpressure to a scaled distance normalised by the cube root of charge weight, reflecting how energy density in the shock front dilutes as the blast wave's volume grows.
Can peak static overpressure alone explain all blast injuries or damage at a scene?+
No, dynamic pressure from the accompanying wind behind the shock front, fragmentation, and secondary effects such as structural collapse all contribute separately, so investigators consider Ps alongside these other parameters rather than as the sole damage predictor.
Related terms
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- Chapman-Jouguet (CJ) Condition
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- Deflagration-to-Detonation Transition (DDT)
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- DMDNB Taggant
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- Dynamic Pressure
- The pressure component due to mass flow of gas behind the shock front, proportional to gas velocity squared; the blast wind that...
- Friedlander Waveform
- The idealised time-pressure history at a point in air following a blast: instantaneous rise to peak overpressure at shock arrival, exponential decay...
- Hopkinson-Cranz Scaling
- The law relating peak overpressure and positive-phase duration to the ratio of range to cube-root-of-charge-mass (the scaled distance Z = R /...
- Mach Stem
- The reinforced shock front that forms near a reflective surface when the direct blast wave and its reflected wave merge, producing anomalously...
- Mott Formula
- An empirical relationship, derived from wartime UK research by N.F. Mott, predicting the statistical distribution of fragment masses from a metal casing...