Controlling pretension of silicone membranes on micro air vehicle wings

Abstract

This study is concerned with a new method to apply consistent and known pretension to silicone rubber membranes intended for micro air vehicles. Pretension has a marked effect on the static and dynamic responses of membrane wings and controls the overall deflections, as such control and measurement of the membrane pretension are important. The technique developed employs thermal expansion to set the pretension and digital image correlation to assess the resulting spatial strain field. Two different frame geometries were fabricated to evaluate the technique. For open-cell frames, the pretension was not uniform, whereas it was for closed-cell frames. Results show developed full-field stress and strain fields as a function of membrane attachment temperature and frame geometry along with experimental iterations to prove repeatability. The membranes can be stretched to a specific pretension according to the temperature at which it adheres to frames.