Membrane wrinkling control usingin situstiffness changes induced by phase transformation

Abstract

A novel concept for controlling surface wrinkles in a nickel titanium (NiTi) membrane is presented. ANSYS is utilized to determine the membrane's length and width as well as thickness to produce wrinkling in a NiTi test sample. Test results conducted on a 20.9 mm × 10.8 mm × 5.54 μm NiTi sample produce wrinkling at approximately 1% strain, which represents the critical strain (ε cr ) to induce wrinkling for this geometry. Using the phase transformation properties and corresponding stiffness change, we demonstrate that wrinkling control (i.e. turning it on and off) is possible simply by changing the temperature through the phase transformation. The maximum amplitude of the wrinkles was 44.8 ± 6.4 μm and the wavelength was 2.10 ± 0.40 mm, in relatively good agreement with analysis.