Shock Sensitivity Test

Shock Sensitivity Shock-sensitive materials react exothermically when subjected to a pressure pulse. Materials that do not show an exotherm on a DSC or DTA are presumed not to be shock sensitive. Testing methods include ... 

M. Held, Initiierung von Sprengstoffen, ein vielschichtiges Problem der Deto-nationsphysik, Explosivstoffe 16, 98-113, (1968) und J. Jaffe, R. Beaugard und Amster. Determination of the Shock Pressure Required to Initiate Detonation of an Acceptor in the Shock Sensitivity Test - ARS Journal 32, 22-25 (1962). 

Drop Tests. See IMPACT SENSITIVITY OR SHOCK SENSITIVITY TESTS... 

IMPACT SENSITIVITY OR SHOCK SENSITIVITY TESTS (Drop Weight or Falling Weight Tests). A list of various tests with refs is given in Vol 1, p XVII. Brief descriptions of US Bureau of Mines (BM) Apparatus and of Picatinny Arsenal (PA) Apparatus are also given on p XVII. British test called Figure of Insensitiveness (FI) is described on p XII (See also Refs 36, 38d, 41, 42, 53, 55b,... 

Detonation (and Explosion) by Impact (or Shock). See Vol 1 of Encycl, p XVII under Impact (or Shock) Sensitivity Test and Vol 2, pp B332 to B340 and Bullet Impact or Rifle Bullet Tests... 

F) I. Jaffee et al, AmRocketSocJ 32, 22-5 (1962) CA 56, 11872(1962) (Shock pressure required to initiate detonation of an acceptor in the shock sensitivity test)... 

AND EXPLOSION), EXPERIMENTAL PROCEDURES . Determination of shock pressure required to initiate detonation of an acceptor in the shock sensitivity test is described in Ref 8 Refs 1) W.C. Holton, "The Detonation Pressure in Explosives as Measured by Transmitted Shocks in Water , NavOrdRept 3968(1954) (Conf) 2) Dunkle s Syllabus (1957-1958), p 175 3) Cook (1958), 68-9... 

Jaffe et al (Ref 3), in the course of determination of the shock pressure required to initiate detonation of an acceptor in the shock sensitivity test, found that the velocity of the front as sensed by the pressure probe method, falls behind the true velocity of the shock front as the shock is attenuated. It has also been found that the maximum transmitted shock velocity generated by the two Tetryl pellets and measured in Lucite is 4.6mm/frsec. Shock velocities determined by optical method, shown in Table 3, p 25, run between 2.701... 

Epreuve au choc de mouton (Shock Test by a Ram). The test with a light weight (such as 2kg) is known as essai au petit mouton , while test with a heavy weight (such.as 30kg) is known as "essai au gros mouton". These tests are listed under Impact (or Shock) Sensitivity Tests in Ref 20, p XVII. See also Ref 24, p E110-L Ref 9, p 560... 

Sensibility au choc de mouton,. Essais (Sensitivity to Shock of a Ram, Tests). Same as Amer Impact (or Shock) Sensitivity Tests. 

Drop Weight (or Impact) Tests. See Impact Sensitivity or Shock Sensitivity Test in Vol 1 of Encycl, p XVII also in Vol 4, pp D321-R... 

Japan 1967, 28(2), 154—58(Japan) From CZ 1968(42), Abstr No 2922 CA 70, 49151j (1969) (Explodability of AN-metal powd systems was investigated by means of shock-sensitivity tests and the Knipp Ignition Test. The results were dependent on the type of metal. The ignition point decreased in the order of metals Znactivation energy of the ignition reaction was ealed from die ignition-delay-time at different temps)... 

Fallhammerprobe (Ger) see Impact sensitivity or shock sensitivity test 1 XVII and F11 XII 4D304... 

In recent years, flyer plate shock sensitivity tests have begun to be used extensively. Basically these tests consist of propelling a thin plate against the expl sample. The variables in this test are plate velocity, plate material and plate thickness. The shock phenomena involved in the flyer plate expts are sketched in Fig 1. The plate velocity at impact is Ufs, the so-called free surface velocity. The intersection of the reflected characteristics of the shock Hugoniot of the plate material (drawn upwards from Ufs) with the P—u curve of the expl then gives the shock state in the expl at the impacted expl surface (P2, u2 in the example)... 

We will postpone consideration of the effects of shock duration on shock sensitivity until we have described shock sensitivity tests (Section III) and take up this subject in Section IV... 

Probably the most frequently used shock sensitivity test is the so-called gap test, in which the shock generated by a standard donor is attenuated in an inert barrier before it enters the test expl (acceptor). Shock strength is varied by varying the thickness of the inert barrier, and results of the test are gaged by terminal observation of the effects of the acceptor on the witness plate or block on which it is placed... 

To put gap test results on a more absolute basis (so that comparisons can hopefully be made between various forms of the gap test as weil as with other shock sensitivity tests) it is necessary to calibrate the donor-gap system so that shock strengths are known as a function of barrier thickness. Details of calibration procedures are found in Refs 4 20a. If the shock Hugoniot of the unreacted test expl is known, the input shock in the test sample at the sample/barrier interface can be determined as discussed in Section II (Figs 1 2)... 

Tetryl has been used as an expl since 1906. In the early part of this century it was frequently used as the base charge of blasting caps but is now replaced by PETN or RDX. During WWII it was used as a component of expl mixts (see Tetrytols in this Vol). Tetryl is still used in military boosters and leads (the expl component of a fuze between the detonator and booster), but even here it is being replaced by plastic-bonded or waxed RDX and HMX expls. A widely used shock sensitivity test employs Tetryl as the donor charge (see Shock Sensitivity of ... 

A shock sensitivity test using a Mklll ballistic mortar (Variable initiator test) has been developed for that purpose 2 0 . One can measure the ease of occurrence of explosions for chemicals with low sensitivity which fall on the boundary of explosives and nonexplosives. The method is place 5g of the test chemical into a 100kg mortar and initiate it with a detonator, which is equivalent to 0.2 - 2.0g of the high explosive PETN. 

Because of the problems with blow and shock sensitivity tests, we sought to develop new test methods. The rank of the sensitivity of explosive substances has been determined by combining the methods shown in Table 3.37. 

Table 3.37 Practical impact shock sensitivity tests...

Applied example of the shock sensitivity test using the MKIII ballistic mortar ... 

The results of shock sensitivity tests on industrial explosives by the small gap tests and variable initiator tests are shown in Fig 3.102. In the range of experiments the shock sensitivity turns out to be smaller. They are listed in order of their sensitivity as follows No.2 Enoki Dynamite, No.3 Kiri Dynamite, Energel MA-7, No.5 Black Carlit, Akatsuki Carlit, Iremite, Hamamite, and ANFO. 

Fig. 3.102 Results of shock sensitivity test for industrial explosives...

In the shock sensitivity test using the MKTII ballistic mortar, ANFO, DPT and DNB are identified as low-sensitivity explosives of almost equivalent sensitivity 2 7 >. The sample were put into VP-30 and VP-50 tubes and ignited by 50g of Airemite and 100 g of Airemite respectively. The relationship between the length of the explosive charge and the volume of craters is shown in Fig.3.133. 

In a shock sensitivity test using a polyethylene sheet as a shock absorbing material,... 

Ger for Falling Hammer Test). See IMPACT SENSITIVITY OR SHOCK SENSITIVITY TEST in Vol 1, p XVII and FI (Figure of Insensitiveness Test> described on p XII... 

---