Tailorable thermal expansion hybrid structures

A design concept is presented for a macro or microstructure that combines materials with differing thermal expansion to achieve an overall effective expansion that differs substantially from either of the constituents. Near-zero-CTE and isotropic negative expansion designs are achieved by creating compliant structures where overall expansion is compensated by internal bending deformation. Such structures have application where dimensional stability is required when subject to large thermal gradients, e.g. space mirrors. In this paper, we present closed form analytic expressions for prediction of the effective expansion, and consequent internal stressing, of the structure, as well as several finite element simulations that demonstrate the design performance under non-uniform thermal load.