DYNAMIC SHEAR STRENGTH OF SiC WHISKER REINFORCED ALUMINUM ALLOY COMPOSITES

ABSTRACT Dynamic shear strength of SiC whisker reinforced 6061-T6 aluminum alloy (or SiCw/6061-T6 Al alloy) composites are determined by means of a modified torsional split Hopkinson bar apparatus. A specially-designed thin-walled tubular specimen is used to eliminate the practical difficulties involved in attaching the specimen to the Hopkinson bars with an epoxy cement. The generation of a torsional loading pulse having a short rise-time is achieved through the sudden release of a torque stored in the portion of the incident bar. Reliable shear stress-strain data are presented at strain rates of over 1500/s for the SiCw/6061-T6 Al alloy composite and the matrix alloy. The experimental results show that the matrix Al alloy 6061-T6 itself is strain-rate independent over a range of strain rates in shear from 10 -3 to about 1700/s, whereas the SiCw/606l-T6 Al alloy composite exhibits apparent strain-rate dependence.