Measurement of strain wads dynamics

Discussion on the pages of the iris of the wads of deformation does not fade, and the number of comments is approaching fifty. Of course, different people have different points of view on this and other matters, which is quite natural. As you know, in a dispute born truth, and the criterion of truth — practice.

Measurement of strain wads dynamics

I’ll try to expand a little bit about it, adding to the static requirements (see. EGR №10) dynamic tests. For this purpose, the device has been made, shown in Figure

Tests were conducted as follows. In the sleeve 3 inserted two wad-container Donets, directed towards each other. The gap between pyzhami filled with liquid. The containers are inserted rods 6 and 7 and at both ends sleeves 3 worn cutting sleeve 1 and 5 so that their edge is flush with rods.

When testing the device was put vertically on a hard surface, and on top of the stock falling load. By measuring the distance between the bushes before impact and after it was possible to determine the degree of deformation «cushioning» of the wads. And measuring the distance between the ends of the rods before and after the impact could find the degree of permanent deformation wads.

Since the cap «Zhevelo» According A.Mozharova able to create pressure in the sleeve up to 42 kgf / sm.kv.. (41 bar), and the area of ​​the inner diameter of the sleeve and the bore 12-gauge is 2.96 sm.kv., the pressure force of 1210 N (124 kgf).

Under the influence of such force «cushioning» wad portion is crushed to 7 mm, and at 75 bars wad wrinkled by 1 mm and then further deformation occurs. To compress the wad of 7 mm, the required energy is 8.5 J and the two wad 17 J. Since I used a weight of 9 kg, the height of the fall sostavila.19 see.

Tests have shown that with repeated measurements of two wads strain ranged from 9.5 to 10.5 mm, that is an average of 10 mm. Thus, these tests make it possible to imagine how wad container behaves when fired.

So when arming cartridge powder «Falcon», The manufacturer recommends that the powder compress the powder 10 kg force, representing 8% of the static deformation wad. With the explosion of the capsule «Zhevelo» deformation is 5 mm or 71% of the static deformation, which gives a total of 79%.

Began burning gunpowder continues to increase the pressure in the sleeve, continuing crease wad, and the time of reaching the maximum pressure of 600-650 bar (!), A crumpled wad COMPLETELY. Namely, when the maximum pressure occurs and the greatest acceleration, deformation and largest fraction.

Thus, it turns out that «cushioning» wad portion container is not only helpful, but even harmful, because deforming reduces the loading density and the initial pressure («boost pressure»). And at a time when, in fact, would be necessary depreciation, then it is not and can not be, because this part of the wad already flattened. So except springs «cushioning» part of the wad-container no other role to play can not.

Maybe my experiments set incorrectly, or the findings do not match the experimental data? Then anyone can put his experiment to prove the correctness of its conclusions.

Igor Arbuzov, photo avtora18 March 2013 at 00:00

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