Cylinder Expansion Test

We describe herein the first analysis of copper cylinder expansion tests with pressed ETN. We discuss the detonation behavior for the material, along with wall velocity and diameter effect information. All data is compared to PETN tested under similar conditions. 

Deteraiination of the Parameters of Explosive Effects From the Cylinder Expansion Test... 

Lead B odi(or Cylinder) Compress on (or Crushing) Tost(Lesd Block Teat or Hess Test) (Stsuchprobe nach Hess, in Ger) (Iipreuve au block de plomh, in Fr) is one of the German teats for brisance, also called percussive force. It will be described in Vol II, under Compression Teats Lead Block Expansion Test. See Trauzl Test Lead Plate Test. See under Plate Tests... 

Abbreviations BMT-Ballistic Mortar Test BPT-Ballistic Pendulum Test CCCT-Copper Cylinder Compression Test FET-Fragmentation Efficiency Test FGT-Fragment Gun Test LBCT-L e ad Block Compression Test PCT-PIate Cutting Test PDT-Plate Denting Test ST-Sand Test and TT-Trauzl Test (Lead Block Expansion Test)... 

The tested expletive is filled into a copper cylinder. The internal diameter of the cylinder is 25.4 mm, its length is 305 mm, and its wall thickness is 2.6 mm. The initiation of the so-prei red explosive charge is performed at the end of the cylinder front 1 a detonator and a booster. Thie cylinder expansion, i.e., the increase of its external radius, is viewed by suitable equipment. For example, a high-spml streak camera may be used. It is positioned to cover a constant section of the cylinder. A t kground illumination ought to be applied. 

The direct experimental output of the cylinder test is the increase of the cylinder external radius as a function of time, i.e., the cylinder expansion curve (Figure 5.16). 

An example of the cylinder test data cylinder expansion curve, wall velocity-time curve, acceleration-time curve, and JWL isentropic expansion curve for Comp B are given in Figures 5.19 and 5.20. 

The proof pressure method is permitted where DOT or TC regulations and specifications do not require the determination of total and permanent volumetric expansion of the cylinder. It consists of examining the cylinder under test for leaks and defects. 

Some experimental cylinder test results at small and large expansions for a varietv of expls are presented below ... 

The power of explosives is determined in a conventional manner. The most usual test is the determination of the lead block expansion and the rate of detonation. In some countries the crushing of lead and copper cylinders is determined. 

Thus from the thin-walled data for Comp B (at a 10-fold expansion) one obtainsy E = 2.96km/sec and E /Q = 0.87. As shown in Section IV (and in particular in Table 5), a tangentially impinging detonation is less effective in propelling incompressible material than a head-on detonation. When this is taken into account (approx 0.87/0.93) E Q if E is based on measurements made at large expansion of the test cylinders... 

The thin-wall bellows element should be designed for membrane stresses to conform to code-allowable stresses. The sum of membrane and secondary bending stresses should not exceed 1.5 times the yield stress in order to prevent the collapse of the corrugations caused by pressure. Bellows subjected to external pressure can be analyzed in a manner similar to a cylinder, utilizing an equivalent moment of inertia. The fatigue life can be estimated based on the sum of deflections and pressure stresses as compared to S/N curves based on bellows test data or using the curves in B31.3 Appendix X, Metal Bellows Expansion Joints. Formulas for the stress analysis of bellows are available in the Expansion Joints Manufacturing Association (EJMA) Standards (37). 

Small scale, unconfined detonation rate sticks were tested at 3.00 0.03 mm and 6.35 0.03 mm pellet diameters. The ETN pellets were pressed to an initial average density of 1.74 0.01 gem 3 (98% TMD), and pellet expansion was not measured thereafter. These measurements gave a detonation velocity of 7.90 0.13 and 8.03 0.04 mmps 1 at 3.00 and 6.35 mm respectively, which are within uncertainty of the adjusted detonation velocities observed in the cylinder tests, given in Table 1. These velocity measurements demonstrate a critical diameter for ETN of <3 mm, which is consistent with the PETN critical diameter of<1 mm [9]. 

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