Evolution Prediction of Bistable Tape Springs' Deployed Shape While Undergoing Stowage at High Temperature

Abstract

Self-deployable tape springs made of CFRP feature significant effect from relaxation, mainly happening during long time stowage in coiled configuration prior to launch. The stored strain energy contained within the structures during stowage tend to modify the polymer matrix mechanical properties. The research introduced here aims to develop an efficient numerical process capable of determining the evolution of the deployed shape, after deployment, of such structures due to viscoelastic relaxation happening during on Earth stowage. A two steps homogenization process is devised to compute the plain weave mechanical properties. The process is first based on an analytical model to determine the strand's properties, before using a finite element based numerical model for the plain weave pattern. Properties are fitted with Prony series to display the variations over a long time range. Results from this homogenization are then used in an Abaqus numerical model to predict the deployed shape evolution of the tape springs, and its recovery capabilities after full deployment. Validity of the model is checked using results from experimental stowage conducted on bistable tape springs.