Thermal expansion of composites with shape memory alloy inclusions and elastic matrix

Incorporation of shape memory alloy (SMA) inclusions into a continue matrix can make composites with various thermal dilatation behavior, and this depends sensitively on the microstructural parameters of the composite. A micro-mechanical method is proposed to relate quantitatively the overall thermal dilatation with the microstructures and the transformation characteristics of SMA materials. Composites with aligned and with two populations of perpendicularly oriented SMA inclusions are analyzed in detail in this paper. It is found that the composite with SMA fibers can have a large transformation temperature range during the heating process, and a linear shrinkage may take place during the cooling because of the large difference between the austenite finish and martensite start temperatures of the composite. Design aspects to minimize the overall thermal dilatation during a full thermal cycle are also discussed.