PSI - Issue 20

Mikhail Kelner et al. / Procedia Structural Integrity 20 (2019) 119–123

120

2

Mikhail Kelner et al. / Structural Integrity Procedia 00 (2019) 000 – 000

be used in any mining and geological conditions. PERC are recoilless devices that consist of a set of expendable reflectors with downhole charges and reflectors with clamping charges. Herewith after the directional flow of the explosion products from the next magazine, the destroyed magazine elements and slime are thrown out of the well by shock waves and expanding gases. After each explosion, the next reflector forms the explosion products into a directional flow, while the reflector itself is partially destroyed and discarded from the unit. The strength of thin-walled shells of magazine reflectors for explosive charges depends not only on the geometric characteristics and charge power, but also on the structural materials mechanical properties that used for their manufacture by Solov'ev and Kelner M. S (2015), Pushkov et al. (2019). A large number of studies by Artsruni and Zagelow (2019), Nikiforovski and Shemyakin (1979) are devoted to the research of the structural materials behavior during explosive effects. In these studies on this issue, it is indicated that the strength characteristics of the material in such conditions are very different from those under static loading. However, only few studies devoted to the explosive charges shell materials tests. This article discusses static loading conditions, but in subsequent studies it is planned to present the results of experimental studies under dynamic (detonation) loading. For the explosive charges shells manufacture or the reflectors manufacture it is important to have the static characteristics of their constituent materials, since at the initial stage it is necessary to exclude those that have unsatisfactory strength properties.

Nomenclature C

efficiency

d/h

ratio of the cavity diameter to its height explosion heat of explosive, J/kg

E

EC HT

explosive charges heat treatment

m explosive mass, kg PERC portable explosive rocket complexes V volume of cavity in lead cylinder, m3 deformation σ с

ultimate compression strength of lead, MPa

tensile strength, MPa

σ t

2. The methodology of the experiment

The following structural materials were selected for research: steel 30HGSA with heat treatment (НТ), steel 65G with НТ, bronze, steel 3, steel 20, steel 45, steel 30HGSA, steel 65G. Static tensile tests were carried out according to GOST 1497-84 on a Shimadzu servo-hydraulic machine. When testing were used samples of type VII. The loading was carried out with a constant load speed of the active grip, which was 0.02 mm/s. Samples were installed in hydraulic grippers with a pressure of 15 MPa. The elongation of the working part of the samples was measured by an extensometer with a base of 25 mm. During the test, a chart was recorded in coordinates load — the movement of the active grip, the elongation of the sample. The destruction of the samples and the deformation diagrams are shown in Fig. 1. The experimental stand for assessing the shells strength was a massive steel plate (substrate), on which a lead cylinder 40 mm in diameter and 20 mm high was installed. On a flat end of cylinder a special electric detonator was mounted in the shell of the structural material under investigation with the help of plasticine, and blasting was carried out by an explosive machine PIV-100M.