Characterising the Self-opening Behaviour of Single Creased Kapton Polyimide Films

Abstract

Use of thin folded membranes for deployable structures are becoming increasingly popular especially in aerospace applications such as a deployable solar array, sun shields, and solar sails. The folding and compaction process of thin membranes, which introduces permanent, nonrecoverable, localized plastic deformation, changes the geometric shape and material properties. The underlying mechanics in the deployment of creased membrane structures are self-opening and then forced-opening beyond a stable stress-free state. The focus of the previous studies was limited to the characterisation of crease behaviour during force opening. This paper presents an experimental study to characterise the crease mechanics of a single creased membrane during self-opening behaviour which is crucial in the design of gossamer structures. A simple analytical study was performed to predict the moment-rotation response of the crease and hence shows a good qualitative agreement with physical experiment results. It is shown that the moment-rotation response of a single crease can be idealized to a linear rotational spring in virtual simulation and the spring stiffness depends on the thickness of the membrane.