A bi-material structure with Poisson's ratio tunable from positive to negative via temperature control

• A 2D quadrilateral cellular structure made from bi-material strips was designed.
• Thermal deformations were studied via experimental, analytical and FEM approaches.
• Poisson’s ratio of the model is tunable from '+' to '−' with a change in temperature.
• A maximum absolute value of the Poisson's ratio is approximately 12.

In this paper, a two-dimensional quadrilateral cellular structure made from bi-material strips was designed and its thermal deformation behaviors were studied via experimental, analytical and numerical approaches. It has been shown that the cell shape of the structure can be tuned from convex to concave (or vice versa) and hence the Poisson’s ratio from positive to negative (or vice versa) with a change in temperature. At any specific temperature with a non-zero ΔT, the absolute value of the structure’s Poisson’s ratio decreased rapidly at first with an increasing compression strain εy and then more slowly as it approached a constant of approximately 1 when εy>0.1. A maximum absolute value of the Poisson’s ratio of approximately 12 was found at εy=0.001 at a 10 °C temperature change.