ELASTIC RESPONSE OF A LAYERED CYLINDER SUBJECTED TO DIAMETRAL LOADING

The elastic stress field produced in an arbitrarily layered cylinder s ubjected to diametrically opposed loads is examined and subsequently e mployed to investigate the transverse strengths of tungsten-cored boro n and carbon-cored silicon carbide fibers measured from diametral comp ression tests. The displacement formulation of linear elasticity and t he local/global stiffness matrix method are used to obtain solutions f or stress and displacement components in a composite cylinder consisti ng of annular linear elastic isotropic shells under the assumption of plane strain. It is found that the presence of the carbon and tungsten cores in the ceramic fibers gives rise to a tensile stress concentrat ion at the core/outer shell interface under diametral compressive load ing. This is shown to contribute to a significant loss of apparent tra nsverse strength. The solution also provides insight into first-stage consolidation of alloy-coated ceramic fibers. Elevated hoop stresses a re shown to occur at fiber-fiber contacts that result in a reduction i n the yield coefficient from that of homogeneous alloy fibers. Thus, t he initiation of the yield mechanism of consolidation can be accomplis hed at lower applied loads when a ceramic fiber is present.