Characterisation of impact response of metallic foam/ceramic laminates

The impact response of laminated composites consisting of alternate layers of AI ahoy foam and Al2O3 was studied experimentally in low and intermediat e velocity regimes. Low velocity impacts (1.2-2.8 m s(-1)) were conducted u sing an instrumented falling weight apparatus and were compared with static indentation tests (0.2 x 10(-4) m s(-1)). Intermediate velocity impacts we re carried out by means of both Hopkinson bar (60 m s(-1)) and gas gun (200 m s(-1)) tests, Post-impact damage was assessed using X-ray radiography an d microscopy, It was found that there is good correlation between low veloc ity impact and quasi-static responses. In both cases, penetration of the la yered targets resulted in the formation of a distinctive plug. Increasing i mpact velocity (intermediate velocity range) snitched the penetration mode from plugging to fragmentation, giving rise to an increase in the absorbed energy. In this range, impacts led to localisation of damage in the region under the projectile, Furthermore, a comparison has been made between the p enetration response of foam laminates and dense metal laminates of equivale nt areal density. Preliminary results suggest that the dense metal laminate s are superseded by the foam laminates on an energy absorption basis. MST/4 575 (C) 2000 IoM Communications Ltd.