COMPOSITES WITH EXTREMAL THERMAL-EXPANSION COEFFICIENTS

We design three-phase composites having maximum thermal expansion, zer o thermal expansion, or negative thermal expansion using a numerical t opology optimization method. It is shown that composites with effectiv e negative thermal expansion can be obtained by mixing two phases of p ositive thermal expansions with a void phase. We also show that there is no mechanistic relationship between negative thermal expansion and negative Poisson's ratio. (C) 1996 American Institute of Physics.