Elastic Constants of Textured Short-Fiber Composites
Martin Dunn, H M. Ledbetter, Paul R. Heyliger, C S. Choi
We studied the transversely isotropic elastic response of a series of textured short-fiber SiC Al metal-matrix composites. By texture we mean the preferred orientaion of the short fibers. We fully characterized the microstructure of the extruded SiC/Al short-fiber composites through a combination of mass-density measurements optical and scanning electron microscopy and neutron diffraction. We measured all components of the overall elastic-stiffness tensor of the composites using two methods: MHz-frequency pulse-echo ultrasonics and kHz-frequency acoustic-resonance spectroscopy the latter being the first application of the method to short fiber or particle reinforced composites. We propose a relatively simple micromechanics model to predict the entire set of elastic constants and give simple results for orientation distributions of practical significance. The predictions are in excellent agreement with measurements.