Quantitative analysis of debris clouds from duralumin and SiC-fiber/aluminum-matrix composite bumpers

In order to investigate the effect of the macro-structure of metal-matrix composite on impact fragmentation, three kinds of bumper plates, i.e. monolithic duralumin, SiC-fiber/pure-aluminum-matrix composite and pure-aluminum lamination were impacted by duralumin projectiles in the velocity range of 2.5–3.7 km/s. The debris cloud extracting to the rear side of each bumper was taken by soft X-ray radiography, and the constituting fragments were recovered in order to find their morphology and mass–size relations. The mass, velocity and kinetic energy of individual in-flight fragments were estimated from the radiographic data and mass–size relation. The quasicontinuous spatial distributions of mass and kinetic energy of each cloud were expressed with their volumetric densities. The effect of material composition on the fragmentation was found in these analyses. The duralumin bumper broke into fewer fragments having a larger mass and kinetic energy at an impact velocity of approximate 3.0 km/s, and the bumper brought the massive and energetic debris distribution biased to the ballistic line. The fragmentation was so enhanced in the debris from the duralumin over the velocity of 3.0 km/s that the mass and kinetic energy was distributed outside to decrease their densities. Such enhanced fragmentation that changed the ballistic-line-biased distributions of debris mass and kinetic energy to their outer spreads was also found in the composite and lamination bumpers. However, the volumetric densities of debris mass and kinetic energy from these bumpers were found to be smaller than those from the duralumin. Thus, the debris dispersed outside from both composite and lamination was thinner than that from the duralumin.