On the negative phase of the shock wave (you do not know about it, but it is) with slides

Dear gentlemen, if you do not understand something about the rationing of explosion barriers, or doubt - ask, we will tell you everything we know, it is free. Remember that according to part 5 of Article 48 of the Civil Code of the Russian Federation, the person preparing the project documentation is responsible for the quality of the project documentation and its compliance with the requirements of technical regulations. Simplifying and coordinating dubious products, you may help to earn counterparties, but take responsibility.

The following is the opinion of the author. 

Areas of blast waves with a pressure greater than that of the environment are called positive phases with a duration of T+. Areas where the pressure is lower than the atmospheric (original) pressure are called negative phases, or dilution phases with duration T- and amplitudes P-s (Fig. 1). 

The most important parameters of the blast wave are positive i+s and negative i-s specific impulses, defined as functions of the time amplitudes of excess pressure assigned to a unit surface: 

At a sufficient distance from the site of the explosion, with a building size smaller than the size to the epicenter i + s + i-s = 0. 

The pulse of the discharge phase (negative) is the same as the compression phase (positive), with a smaller amplitude, but longer duration. 

That is, first the object “cracks”, then a discharge zone is created around, and the air inside the object begins to press on the barrier, towards the street, with the same impulse, quite strongly. 

Below is an illustration of the effect of the negative phase using examples from our tests. 

1. Bending of the pipe 60x40x3 locking the test bench: 

2. Bloating of the test bench. 

3. Deformation of the clamping bar of glass 

4. Deformation of metal in the lock part of the product of a popular domestic manufacturer 

5. Breaking the loop out, in the door of the same manufacturer.

Unfortunately, many design engineers are unaware of this phenomenon. Only ignorance can explain the appearance in the projects of "Explosive"! prefabricated buildings from sandwich panels, screwed over a meter with screws with D 4.7!  

A person who finds himself in such a structure, during an explosion, will obviously experience the whole range of consequences for his own body, an instant decompression before pulmonary borotrauma.