Impact sensitivity drop-weight

In Table 1 we give the drop-weight impact sensitivity (h Q,cm) and the shock sensitivity as measured by the NSWC small scale gap test (P Q the pressure in kbar required to initiate material pressed to 90% theoretical maximum density (TMD), = 95% TMD, Pgg = 98%... 

Figure 1. A plot of the drop-weight impact sensitivity ( 50) vs the NSWC small scale gap test shock sensitivity at 90% TMD for TNB, DIPAM, MATE, DATE, and TATE. Data from Table 1.

TABLE 2. The drop-weight impact sensitivities of nitroaromatic explosives. 

TABLE 4. The drop-weight Impact sensitivities of explosives. 

This nitroguanidine analogue is more sensitive than RDX by the drop-weight impact test. 

No unique relationship between width and length revision has been found (Paschke, 1967). The revision runs parallel with birefringence up to a limiting value. Van Leeuwen showed that a distinct relationship exists between the drop weight impact strength and the birefringence the impact strength is very sensitive to orientation. A less satisfactory correlation with reversion was found. 

A sample placed between two flat, parallel, hardened steel surfaces is subjected to the drop weight impact. Depending on the characteristics of the tested explosive, the drop weight mass, and the drop height (i.e., impact energy), the initiation of the sample may or may not occur. The drop height that enables the initiation of the tested explosive is the measure of its impact sensitivity. 

By far the most commonly used measure of an explosive s sensitivity is the drop-weight impact test. This is convenient, easy-to-run, and inexpensive. An important question is whether this test is indicative of the explosive s behavior under other circumstances, i.e., a shock stimulus. In a typical drop-weight impact test the time constant for reaction is in the range of 200-250 ijls and the pressure is between 7-15 kbar. In a shock experiment the times range from 0.05-2.0 fis and the pressures range from 30-200 kbar. Is the mechanism of decomposition of the explosive at all similar under these rather different conditions ... 

The determination of the mechanical shock sensitivity or impact sensitivity is applicable to both solids and liquids. The principle involved is that a drop weight falls from a specified height onto the confined test sample. The load can be varied by changing the height of the drop and by changing the drop weight. 

More recently, explosives have been tested for impact sensitivity by an impact machine in which 40 mg of explosive on sandpaper are placed between an anvil and a steel cylinder. A 2.5 kg weight is dropped from different heights and the sound produced serves to indicate a go or no go . The result from 25 drops is calculated to give a height at which the probability of explosion is 50%. Results from a compilation104 are presented in Table 12 and show that the relative values of TNT and picric acid are reversed from the previous table. TNT is relatively more sensitive on the Type 12 impact machine than in the FI impact test. TATB is so insensitive that it fails to explode at the maximum drop height of the machine. 

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