Blast mitigation

Abstract

An apparatus and a method for mitigation of the effects associated with both blast and shrapnel. The mitigating apparatus is designed with alternating layers of blast mitigating substance, preferably liquid or hydrophilic gel or other viscous fluid, and anti-ballistic substance, preferably a textile, to treat both the air shock wave and the bomb-generated fragmentation and shrapnel, which originate from a detonation or explosion.

Description

FIELD OF THE INVENTION[0001]The present invention relates generally to the field of blast mitigation that results in a decrease of the damage associated with explosives.BACKGROUND OF THE INVENTION[0002]Terrorist attacks which target civilians and public places by using charges and bombs, as well as ordnance and explosives in storage, etc., are common in today's world. When such a bomb or charge explodes, it can damage nearby buildings and structures and may result in injuries and even fatalities. The damage, which originates from the blast, is caused by two main phenomena: the air shock waves and the shrapnel, which propagate following the blast. The air shock waves are short duration compressive waves, which move radially outward through the air from the blast source. These high pressure waves, which propagate immediately, create a shock wave which causes devastation through their propagation. The shock waves also heat the air to extremely high temperatures, a phenomenon known as t...

AI Technical Summary

Benefits of technology

[0010]There is provided according to the present invention an apparatus and a method for mitigation of the effects associated with both blast and shrapnel. The mitigating apparatus is designed with alternating layers of blast mitigating substance, preferably liquid or hydrophilic gel or other viscous fluid, and anti-ballistic substance, preferably a textile, to treat the two main causes of damage originating from a detonation or explosion, namely, the air shock wave, which is the first to propagate after the explosion, and the bomb-generated fragmentation and shrapnel, which propagate following the air shock wave. The fluid suppresses the air shock wave, absorbing some of its energy, and the anti-ballistic textile layers inhibit continued movement of the shrapnel.

[0012]The blast mitigation substance of the apparatus is held in at least one closed compartment, which surrounds the explosive charge. The lower or inner wall of the compartment is placed on top of or around the explosive and is made of a material which is ruptured by the air shock wave created in the explosion. The upper and / or external walls of the compartment are covered with or made of anti-ballistic textile. In this way, the apparatus absorbs the shock wave's energy without being completely dismantled, and is still able to suppress the shrapnel's kinetic energy and decrease the damage it can cause.

[0014]Preferably, a special section of the most external layer, or certain sections of other layers, are specially designed to allow the remainder of the shock wave's energy not absorbed by the liquid, to be released in a defined direction. In one embodiment of the invention, this design includes at least one layer of an anti-ballistic textile sheet attached to the outer cover of the apparatus only on one side thereof. This facilitates release of the remainder of the high pressure shock wave along the other side of the sheet, in a pre-selected upward direction.

[0016]The apparatus may be provided with the blast mitigating substance already inside its compartments, or it may be provided empty and be filled on site with the blast mitigating substance. When the blast mitigating substance is a hydrophilic gel, powdered gel may be provided inside the compartments, and the compartments can be filled with water on site. Upon filling, the powdered gel absorbs the water and expands to form an hydrated, protective gel, while retaining the blast mitigating characteristics of the water. The fact that the apparatus may be filled with the blast mitigating substance on site enables it to provide protection also against large size explosive charges. In such cases, the empty apparatus is considerably lighter (and smaller) than the filled apparatus, and can be carried by a single person. The apparatus is positioned on top of or around the explosive charge, and following that, can be filled with water or other fluid using a filling connection. Furthermore, after use, the gel can be dissolved in additional water and easily washed away.

Problems solved by technology

When such a bomb or charge explodes, it can damage nearby buildings and structures and may result in injuries and even fatalities.

These high pressure waves, which propagate immediately, create a shock wave which causes devastation through their propagation.

The shrapnel, which is spread following the blast, gains its high kinetic energy from the blast's energy and, therefore, is another source of damage and devastation.

The effect of the water is limited with regard to shrapnel which originates from the charge and follows the shock wave.

Thus, when the shrapnel interacts with the mitigating material, such as water, which is present in the prior art systems, this mitigating material has already interacted with the shock waves and, therefore, the effectiveness of the liquid with regard to stopping the energetic shrapnel is significantly reduced.

The inability of existing devices to effectively mitigate both the shock wave energy and the shrapnel energy is becoming more and more of a liability, as terrorists' charges deliberately contain metal nails and other sharp metal debris.

However, since silicone gel has no water, it does not mitigate blast waves and cannot be washed away after use.

Furthermore, the device must be filled in advance and is extremely heavy.

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