François Guinot

Buckling analysis of tape springs using a rod model with flexible cross-sections

This work is devoted to the study of tape springs behaviour. We focus on the instabilities that lead to the creation of localised folds, due to the flattening of the cross-section. Depending on the kind of loading, the folds can move along the tape, split or disappear. Using an extended four parameters rod model with flexible cross-sections, we study several modes of instabilities (number and localisation of folds) for such structures submitted to an overall compression or bending.

On the folding and deployment of tape springs: A large displacements and large rotations rod model with highly flexible thin-walled cross-sections.

In the framework of deployable structures, we focus on the modeling of tape springs, i.e. rod-like elastic bodies with thin-walled cross-section which develop localized folds due to a flattening of the cross-section. A rod model with highly deformable cross-section and few kinematics parameters is derived from a complete shell model, for large displacements, large rotations and dynamics. The simplicity of the model is achieved by introducing an elastica kinematics to describe the changes in the cross-section shape. This model is able to handle the formation of localized folds which can move along the rod line, merge or split, allowing to simulate complex scenarios of folding and deployment.

Hybrid tape-spring for deployable hexapod

In this work we present a new concept of a hybrid tape-spring for the deployment of space structures. The control of its unreeling, needed to avoid any risk of damage, is achieved thanks to a local heating of thermoplastic layers stuck on its surface. The lay-up properties and the geometry are chosen by minimizing the strain energy of the coiled state. The feasibility of the concept is proved experimentally and numerically thanks to a rst ABAQUS FEM model describing the coiling and the unreeling of the tape-spring.