When a high order explosion is initiated, a very rapid exothermic chemical reaction occurs.

As the reaction progresses, the solid or liquid explosive material are converted to very hot, dense, high-pressure gas.

CalcuThe explosion products initially expand at very high velocities in an attempt to reach equilibrium with the surrounding air, causing a shock wave.

A shock wave consists of highly compressed air, traveling radially outward from the source at supersonic velocities.

Explosive detonations create an incident blast wave, characterized by an almost instantaneous rise from atmospheric pressure to a peak overpressure.

As the shock front expands pressure decays back to ambient pressure, a negative pressure phase occurs that is usually longer in duration than the positive phase .

At some distance from the explosion center the region of positive pressure, or overpressure, in the shock wave is followed by a region of negative pressure, or under pressure.

The under pressure is quite weak and does not exceed about 4 psi.

The negative phase is usually less important in a design than the positive phase.

When the incident pressure wave impinges on a structure that is not parallel to the direction of the wave’s travel, it is reflected and reinforced, producing what is known as reflected pressure. The reflected pressure is always greater than the incident pressure at the same distance from the explosion.

The reflected pressure varies with the angle of incidence of the shock wave.

When the shock wave impinges on a surface that is perpendicular to the direction it is traveling, the point of impact will experience the maximum reflected pressure.

When the reflecting surface is parallel to the blast wave, the minimum reflected pressure or incident pressure will be experienced.

In addition to the angle of incidence, the magnitude of the peak reflected pressure is dependent on the peak incident pressure, which is a function of the net explosive weight and distance from the detonation

• Peak Overpressure

• Blast Scaling

• Arrival and Duration Time

• Overpressure Impulse

• Scaled Peak Overpressure

• Scaled Impulse Pressure

• Scaled Duration Time

• Shock Velocity

• Particule Velocity

• Peak Dynamic

• Peak Refelected Overpressure

• Over Pressure P

• Net Pressure PNet