HIGH STRAIN-RATE COMPRESSION TESTING OF A SHORT-FIBER-REINFORCED ALUMINUM COMPOSITE

Compression behavior of 15-26V(f)% Saffil(TM) short-fiber reinforced A l-1.17wt.%Cu alloy metal matrix composites has been determined over a strain-rate range of approximately 10(-4) to 2 x 10(3) s(-1). The stra in-rate sensitivity of composite samples at 4% strain, tested parallel and normal to the plane of reinforcement, was found to be higher than that of unreinforced alloy in the strain-rate range studied. Quantita tive analysis of fiber fragment lengths from samples tested to differe nt strain levels showed that, at small strains, high strain-rate testi ng induced a relatively shorter fiber fragment length distribution in the composite compared to quasi-static testing. At quasi-static strain rates, the fiber strengthening effect was found to increase with incr easing V-f% and was higher in samples tested parallel to the planar ra ndom array. The observed anisotropy of the composite at quasi-static s train rates was also observed to continue into the high strain-rate re gime. Microscopic observations on composite samples tested quasi-stati cally and dynamically to a range of strains showed that the major dama ge process involved during compression testing was fiber breakage foll owed by the microcracking of the matrix at relatively large strains. F iber breakage modes were found to be mostly shearing and buckling. (C) 1997 Elsevier Science S.A.