Dynamic deformation of advanced materials

Abstract

This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The objective of this project was to provide high-quality experimental measurements on composite materials and to develop computational models describing the deformation response of these materials. Specifically, the authors studied the influence of strain rate and shock loading on the deformation and fracture response of a 6061-T6 Al-50 vol.% Al{sub 2}O{sub 3} continuous fiber-reinforced composite as a function of composite orientation. The stress-strain response was found to vary substantially as a function of loading orientation with the quasi-static yield changing from nominally 300 MPa transverse to the fibers to {approximately}1,000 MPa parallel to the fibers. Transverse VISAR wave profile and spall measurements revealed a small, well-defined elastic precursor followed by a reasonably sharp shock rise. The failure response of the composite transverse to the fibers, under both uniaxial stress (quasi-static and dynamic) and uniaxial strain loading, displays a protracted but substantial load drop after yield followed by continued degradation in load carrying capacity. Lack of ideal parallel fiber construction leads to systematic bending failure of the alumina fibers through the sample under uniaxial stress and slow spallation kinetics as various fibers fail and pull out of the matrix across the spall plane.