Analysing wrinkle interaction behaviour with Z-fold crease pattern in thin-film planar membrane reflector

Abstract

Limited stowage volume of launch vehicles demands compact packaging of large deployable membrane structures. Employment of different folding approaches led to the unavoidable fold-lines(creases). Moreover, wrinkle reduction is essential in such thin-film solar sail and inflatable antenna structures. This article analyzes the combined effect of multiple creases and wrinkles on deployed thin Kapton’s surface accuracy. Authors have introduced a novel approach for employing membrane length shortening because of multiple creases and fold characteristics. Real-world logarithmic behaviour of crease relaxation and fold-region properties help in computing the crease curvature. A rhombus-shaped shell model with Z-folding is introduced and explored for the effect of the number of creases and their orientation. Stress concentration and wrinkle contours for applied edge tensile loading state that the fold lines affect the stress transfer path. Non-linear post-buckling analyses for the Kapton® membrane express higher wrinkle evolution in the central region over the loading edge. Besides, a discrepancy in wrinkle amplitude and wavelength reveals the effect of fold-line orientation on wrinkling. Sighting actual conditions for antenna structure, creasing profile normal to the loading direction was found preferable for maintaining reflector surface-effectiveness. Additionally, double creased membranes achieve maximum surface correctness for any angular position, as the mirror effect fold shapes reduce wrinkles the most. Results are validated by comparing with experimental outcomes.