Effect of curvature on durable ice-phobic surfaces based on buckling metallic plates

Abstract

Degradation in system performance due to ice accretion on curved surfaces remains a decades-old challenge. We recently reported that Buckling Elastomer-like Anti-icing Metallic Surfaces (BEAMS) exhibit a low ice adhesion strength and extreme durability in realistic icing conditions. BEAMS consist of thin, flat metal sheets suspended on strips or dots of adhesive, and this partial confinement facilitates buckling of the metal sheet, causing ice to dislodge from the surface at a low applied force. The mechanism of ice detachment from curved BEAMS has not been investigated. Here we study how curvature affects the shear ice adhesion strength of BEAMS, using both glaze- and rime-type ice at −20 °C. For glaze, it was observed that increasing the radius of curvature increased the ice adhesion strength regardless of whether the curvature was positive or negative. For rime ice a high radius of curvature, R = 17.3 mm, was used inside an icing wind tunnel. When the compliance of the material used to suspend the metallic sheet was increased, the rime ice adhesion strength was as low as τice≈3 kPa. Further, the confinement configuration of BEAMS was studied to understand its effect on lateral torsional buckling. Lateral torsional buckling altered the radius of curvature of both the suspension material and metal sheet, initiating cracks due to the unchanged curvature of the accreted ice. Accordingly, the extremely low ice adhesion strength of BEAMS, even on curved surfaces, was due to buckling instabilities either within the thin metal plates or the suspension material. Overall, BEAMS would appear to be a durable, low-ice-adhesion candidate material even for complex and curved surface geometries such as the leading edges of aircraft wings, wind turbine blades, or power transmission lines.