Thermal expansion of morphologically textured short-fiber composites

We studied, both experimentally and theoretically, the thermoelastic response of short-fiber composites with a preferred orientation of the short fibers, i.e., a morphological texture. Our theoretical efforts are general, being applicable to any composite system with constituents that exhibit linear thermoelastic response. We propose a relatively simple micromechanics model to predict the thermal expansion coefficient (CTE), and give simple, easily used, results for orientation distributions of practical significance. We also present a convenient approach to represent the effects of texture on thermal expansion of short fiber composites, namely, a texture map. Our experimental efforts focus on a series of extruded SiC/Al short-fiber composites that we have fully characterized. This includes measurement of the complete set of elastic constants, the volume fraction, and the fiber orientation distribution function (ODF) using neutron diffraction. We measured the axial and transverse components of the overall CTEs of these composites using a quartz-rod dilatometer. Predictions are in good agreement with measurements.