High-Strain-Rate Constitutive Characterization and Modeling of Metal Matrix Composites

摘要

The mechanical response of three different types of materials are examined: unidirectionally reinforced continuous fiber Al2O3/Al metal matrix composite, random fiber Saffil-fiber aluminum matrix composite, and a satin- weave Nextel fiber reinforced aluminum matrix composite. Quasi-static tests and specially designed dynamic tests have been performed. For the split-Hopkinson bar test, in addition to the conventional measurements of the strain signals in the input and output bars, direct images of the deformation of the specimen were obtained using a Photron SA1 high speed video camera at 10s time intervals. These measurements indicated that the deformation was localized due to the formation and propagation of a kink band. Based on an analysis of the power balance in the specimen, the rate of dissipation at the propagating kink band was estimated and used subsequently to determine that the dynamic dissipation was significantly greater than the quasi-static dissipation in the same material. The underlying reason was explored through a microscopic examination and attributed to increased fiber breakage under dynamic loading conditions. This report also documents some of the highlights of the material response of Saffil filled aluminum matrix composite and a Nextel satin weave reinforced aluminum matrix composite.