Fragmentation test

Figure 6.32 illustrates results of three fragmentation tests of 4.85-m vessels 50% full of liquid propane. The vessels were constructed of steel (StE 36 unalloyed... 

Because of the viscoelastic interactions in polymers, the fragmentation test may not always yield the... 

Explosive D is approx 80% as brisant as TNT, as indicated by sand tests, but fragmentation tests in shell have shown it to be about 95% as brisant. Both expls have about the same rate of detonation at a d of 1.56g/cc hence, approx equality of brisance would be expected. The rate of detonation of Explosive D has been found to be somewhat affected, particularly at lower loading densities, by the granulation of the material, but this effect is not pronounced. Its expl strength is 98% that of TNT, as evidenced by the ballistic pendulum test (see below)... 

Static Fragmentation Tests of High-Energy Munitions, U.S. 

Fig. 8.10 The porous structure and high specific surface of CNT fibers enhances adhesion to polymer matrices (a) shows the cross-section of fiber/epoxy fractured specimen, evidencing good wetting by the polymer [9] (b) shows fragmentation tests on CNT fibers in epoxy, for fibers infiltrated with PVA (a) and PI (b) [78]. With kind permission from Elsevier (2009, 2011).

The fiber fragmentation test is at present one of the most popular methods to evaluate the interface properties of fiber-matrix composites. Although the loading geometry employed in the test method closely resembles composite components that have been subjected to uniaxial tension, the mechanics required to determine the interface properties are the least understood. 

Fig. 3.2. (a) Dog-bone shape fiber fragmentation test specimen (b) fiber fragmentation under progressively increasing load from (i) to (iii) with corresponding fiber axial stress of profile. 

Fig. (a) Typical load-displaccnicnt curve and (b) acoustic emission events for a fiber fragmentation test on an AS4 carbon fiber PEEK matrix composite. After Vautcy and Favre (1990). 

It has been noted in a round robin test of microcomposites that there arc large variations in test results for an apparently identical fiber and matrix system between 13 different laboratories and testing methods (Pitkethly et al., 1993). Table 3.1 and Fig 3.15 summarize the IFSS values of Courtaulds XA (untreated and standard surface treated) carbon fibers embedded in an MY 750 epoxy resin. It is noted that the difference in the average ISS values between testing methods, inclusive of the fiber fragmentation test, fiber pull-out test, microdebond test and microindentation test, are as high as a factor of 2.7. The most significant variation in ISS is obtained in the fiber pull-out /microdebond tests for the fibers with prior surface treatments, and the microindentation test shows the least variation. 

Fig. 3.15. Interface shear strength. Xb, of (a) untreated and (b) treated LXA500 carbon fiber-epoxy matrix system measured at 10 different laboratories and using different testing methods. (O) fiber pull-out test ( ) microdebond lest ( ) fiber push-out lest (A) fiber fragmentation test. After Pitkelhly el al. (1993).

Favre, J.P. and Jacques, D. (1990). Stress transfer by shear in carbon fiber model composites Part I Results of single fiber fragmentation tests with thermosetting resins. J. Mater. Sci. 25, 1373-1380. 

Kim, J.K. (1997). Stress transfer in the fiber fragmentation test, part IFF. Effects of interface debonding and matrix yielding. J. Mater. Sci. 32, 701-711. 

Lacroix, Th., Tilmans, B., Keunings, R., Desaeger, M. and Verpoest, F. (1992). Modelling of critical fiber length and interfacial debonding in the fragmentation testing of polymer composites. Composites Sci. Technol. 43, 379-387. 

Rao, V., Herrera-Franco, P., Ozzello, A.D. and Drzal, L.T. (1991). A direct comparison of the fragmentation test and the microbond pull-out test for determining the interfacial shear strength. J. Adhesion. 34, 65-77. 

Fig. 4.6. Schematic drawing of a partially debonded single fiber composite model subject to external stress, (Ta, in the fiber fragmentation test.

Fig. 4.7. Distributions of (a) fiber axial stress, a, (b) matrix axial stress, Om., and (c) interface shear stress. T along half the embedded fiber length, L, in the fiber fragmentation test.

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