Abstract
While a solar or drag sail segment is packaged, packaging folds are introduced across the segment. Understanding elastic-plastic behaviour in polymers undergoing large displacements is important in forming processes due to the tendency of shape alteration or ploua springback once the forming force is removed. By tracking the stresses and strains during folding, residual stress distribution in the polyner segment is known. A numerical model has been derived for the compression of a polymer film in between two plates. The polymer film is modelled as an isotropic cantilever under the action of a bending moment undergoes elastic-plastic, relaxation and springback. The fundamental Euler-Bernoulli equation has been adapted for large displacements. The results show good agreement at small and large curvatures for the displacement of the foil.